For full functionality of ResearchGate it is necessary to enable JavaScript. Here are the instructions how to enable JavaScript in your web browser.

GENETIC IMPROVEMENT OF WHEAT-A REVIEW

Article (PDF Available) · January 2009 with 1,911 Reads

Zuzana Sramkova
9.02
Slovak Academy of Sciences
Edita Gregová
23.81
National Agricultural and Food Centre/Research Institute of Plant Production
Ernest Šturdík

Abstract

Bread wheat (Triticum aestivum L.) plays a major role among the few crop species being extensively grown as staple food sources. As the human population grows, new methods and approaches must be found to attain wheat cultivars with improved characteristics. The challenge now is to produce higher-yielding varieties with good technological quality that are resistant or tolerant to a wide range of biotic and abiotic stresses. However, because of the critical nutritional status of human population, there is an urgent need for development of such wheat varieties that would be more nutritious (with improved protein, zinc, iron, etc. value), meeting our health demands. This article summarises present status in this field.

Figures

Nova Biotechnologica 9-1 (2009) 27

GENETIC IMPROVEMENT OF WHEAT- A REVIEW

ZUZANA ŠRAMKOVÁ1, EDITA GREGOVÁ2, ERNEST ŠTURDÍK1

1Institute of Biochemistry, Nutrition and Health Protection, Faculty of Chemical and

Food Technology, Slovak University of Technology, Radlinského 9, Bratislava,

SK-812 37, Slovak Republic (zuzana.sramkova@stuba.sk)

2 Plant Production Research Centre, Research Institute of Plant Production;

Piešťany, SK-921 01, Slovak Republic (gregova@vurv.sk)

Abstract: Bread wheat (Triticum aestivum L.) plays a major role among the few crop species being

extensively grown as staple food sources. As the human population grows, new methods and approaches

must be found to attain wheat cultivars with improved characteristics. The challenge now is to produce

higher-yielding varieties with good technological quality that are resistant or tolerant to a wide range of

biotic and abiotic stresses. However, because of the critical nutritional status of human population, there is

an urgent need for development of such wheat varieties that would be more nutritious (with improved

protein, zinc, iron, etc. value), meeting our health demands. This article summarises present status in this

field.

Keywords: biotic/abiotic factors, genetic transformation, grain yield, nutritional quality, plant breeding,

wheat

1. Introduction

Wheat (Triticum spp.) is a self-pollinating annual plant, belonging to the family

Poaceae (grasses), tribe Triticeae, genus Triticum. According to different

classifications, number of species in the genus varies from 5 to 27 (MEREZHKO,

1998). The two main groups of commercial wheats are the durums (Triticum durum

L.) and bread wheats (Triticum aestivum L.) with 28 and 42 chromosomes

respectively. The wild species are still a valuable source of useful agronomic traits for

the continued improvement of cultivated wheats. Wide hybridization of wheat with

grasses, coupled with cytogenetic manipulation of the hybrid material, has been

instrumental in the genetic improvement of wheat. Chromosome engineering

methodologies based on the manipulation of pairing control mechanisms and induced

translocations, have been employed to transfer into wheat specific disease and pest

resistance genes from annual (e.g., rye) or perennial (e.g., Thinopyrum spp.,

Lophopyrum spp., and Agropyron spp.) members of the tribe Triticeae. The use of

DNA markers helps to identify desirable genotypes more precisely and facilitates gene

transfer into wheat. The development of novel gene-transfer techniques that allow

direct delivery of DNA into regenerable embryogenic calli has opened up new avenues

of alien-gene transfer into wheat cultivars. Thus, transgenic bread and durum wheats

have been produced. The application of transgenic technology has not only yielded

herbicide-resistant wheats, but has also helped to improve grain quality by modifying

the protein and starch profiles of the grain (REGINA et al., 2006; BICAR et al., 2008).

Recently, biofortification of cereal crops with micronutrients (vitamins, minerals, etc.)

using plant breeding and/or transgenic strategies has become of great interest.

28 Šramková, Z. et al.

Approaches to gene transfer are developing rapidly, and promise to become an integral

part of plant breeding efforts. However, the new biotechnological tools will

complement, not replace, conventional plant breeding (JAUHAR and CHIBBAR,

2001; VASIL, 2007).

2. History, cultivation, production and green revolution

Wheat in its present-day form has gone through a long and interesting evolution.

The origin of the genus Triticum (wheat) is found in Asia, in the area known as the

Fertile Crescent, and parts of Africa, in the area that stretches from Syria to Kashmir,

and southwards to Ethiopia. The genetic relationships between einkorn and emmer

indicate that the most likely site of domestication is near Diyarbakir in Turkey. The

cultivation of wheat began to spread beyond the Fertile Crescent during the Neolithic

period. By 5,000 years ago, wheat had reached Ethiopia, India, Great Britain, Ireland

and Spain. A millennium later it reached China (DUBČOVSKÝ and DVOŘÁK,

2007).

All the species belonging to the genus Triticum can be divided into three basic

groups, each distinguished by the number of chromosomes in the generative and

vegetative cells. Unfertilized egg cells contain 7, 14 or 21 chromosomes. In vegetative

cells this number is doubled. Consequently, diploid, tetraploid and hexaploid wheat

species carry 2x7=14; 4x7=28 and 6x7=42 chromosomes, respectively (BELDEROK

et al., 2000).

Hexaploid wheat is believed to have arisen, when genomes of tetraploid wheat (T.

turgidum, 2n=28, AB-genome) and Aegilops squarrosa L. (also called Triticum

tauschii) were combined via amphidiploidisation (Fig. 1). Aegilops is a species

without any economic value that grows as a weed on the borders of wheat fields in the

Near East and it has a somatic chromosome number of 14. These chromosomes belong

to the D-genome. Therefore, the genome of T. aestivum is called the ABD-genome

(DVOŘÁK, et al., 1998). The bread wheats (T. aestivum L.) encompass a wide range

of different types classified largely by their growth habit and functionality. The

various classes are combinations of winter or spring growth habit with white or red

and hard- or soft-textured kernels. Since only the hexaploid wheat cultivars,

possessing the D set of chromosomes, have the unique milling and baking properties,

these desirable quality characteristics have been attributed preponderantly to the third

genomic component (BELDEROK et al., 2000).

An important attribute of wheat is its adaptability to varied climatic conditions.

Although grown mostly in temperate climates (between latitudes 30° and 60° north

and south) with an optimum growing temperature of 25°C (minimum and maximum

temperatures of 3°C and 32°C), it can be grown from within the arctic circle to higher

elevations near the equator, and from sea level to as much as 3000m above sea level.

As such, it is one of the most widely cultivated crops with a short growing season, and

a good yield per unit area. These attributes makes wheat one of the most important

commodities in international trade (VASIL, 2007).

With 607 mMT (million metric tons) produced on 217 mha (million hectares) in

2007, wheat continues to be one of the largest food crops in terms of area of

Nova Biotechnologica 9-1 (2009) 29

cultivation as well as production (FAOSTAT, 2007; Table 1). The IGC's (International

Grains Council) current estimate for production in 2008 is 683 mMT (source: IGC,

http://www.igc.org.uk/; 2008).

Fig. 1. Evolution of cultivated wheat: the diploid (2n = 14, AA) forms of T. monococcum (a) were naturally

pollinated by weed species (2n = 14, BB). The subsequent genome duplication of hybrids by natural

polyploidy gave rise to several wild and cultivated tetraploid species (2n = 28, AABB) like T. dicoccum (b)

and T. durum; again, the natural pollination of the tetraploid T. dicoccum (b) by Aegilops squarrosa (2n =

14, DD) gave rise to the hexaploid (2n = 42, AABBDD) species (c) (from FERNANDES et al., 2000).

In the middle of the twentieth century, wheat breeders were faced serious problem:

increases in productivity have fallen below the rate of population growth. At the

request of the Mexican government and the urging of the USA, a program to develop

high-yielding and disease-resistant varieties of wheat started in Mexico in 1944.

Norman Borlaug and his team first developed disease-resistant varieties and then

crossed these with the Japanese dwarf variety Norin 10, to produce semi-dwarf,

disease-resistant and high-yielding varieties of wheat (HEDDEN, 2003). These new

varieties- which made more grain and less stem- formed the basis of the “Green

Revolution”, which has allowed many countries (such as India, Pakistan, China, etc.)

to be self-sufficient and food production to keep pace with worldwide population

growth (VASIL, 2007). Before the period of the Green Revolution, the farmers in

Slovakia cultivated tall historical wheat cultivars (landraces), with insufficient seed

yield. Later, wheat cultivars originated in Czech Republic and Soviet Union were

adopted. From the year 1967, there were no Slovak varieties grown in Slovakia. From

1945 to 1970, sixteen breeding stations were established and Slovak wheat breading

began to progress rapidly. New, modern semi-dwarf wheat varieties with higher yields

and improved resistance to pathogens replaced the tall traditional varieties like in

almost all countries over the world. Between the years 1976 and 2008, 47 wheat

cultivars of Slovak origin were included in the National List of Released Varieties

(ANONYMOUS, 2008).

30 Šramková, Z. et al.

Wheat production will have to be doubled to 1200 mMT by the 2025 in order to

meet increasing world demands and future needs. This increase must be brought about

by improving productivity on land that is already under cultivation and not by bringing

new land into use by destruction of forests, grasslands, etc. (VASIL, 2003). Such

significant increases in yield are unlikely to be attained through only the traditional, or

even the newly developed marker-assisted breeding methods, because neither the

germplasm of wheat nor its close relatives is likely to contain the wide variety of genes

that would be needed to meet future demands. Therefore, new methods and

approaches must be found to integrate useful genes from any organism (plants,

animals or microorganisms) to attain the dramatic yields that would be required to

meet future demands: (1) Significantly reduce or eliminate productivity losses caused

by pests, pathogens and weeds (OERKE et al., 1994), and the substantial additional

losses attributed to abiotic factors (drought, salinity, etc.) as well as post-harvest

spoilage during storage. (2) Fundamental improvement of the physiological capability

or limit of the plant by increasing its photosynthetic efficiency and nutrient utilization

in order to attain higher yields. Moreover, the number of micronutrient-malnourished

people is raising, therefore the improvement of nutritional quality of wheat as a staple

crop must also be of interest to plant breeders.

Table 1. Production quantity of the most important cereal crops.

Production quantity [million tonns]/Area harvested [million hectars]

Year

Cereal crop

2005 2006 2007

maize 716/ 148 699/ 147 785/ 158

rice 632/ 155 644/ 156 651/ 157

wheat 626/ 220 598/ 214 607/ 217

Source: FAOSTAT (http://www.faostat.fao.org)

These objectives require the introduction of novel- and in many instances alien and

multiple- genes into commercial varieties of wheat by genetic transformation, and

production of transgenic varieties with the desired attributes (VASIL, 2003). However,

high costs currently limit the implementation of functional genomics in breeding

programs. Genomics research will continue to enhance the efficiency and precision for

crop improvement but will not totally replace conventional breeding and evaluation

methods (VARSHNEY et al., 2007)

3. Approaches to genetic improvement

Landraces of cereal crops contain an array of genes for agronomically important

traits. These landraces fall in the primary gene pool with their respective crop species

with which they can be easily crossed. Complete or high pairing between

chromosomes of the landrace and those of the crop plant facilitates alien gene transfer

into the crop species (VASIL, 2007).

Many wild relatives of wheat carry genes that offer superior traits, some of which

have been incorporated into wheat via interspecific and intergeneric hybridization

Nova Biotechnologica 9-1 (2009) 31

(JAUHAR and CHIBBAR, 1999). Chromosome pairing between chromosomes of the

alien donor and those of cereal crops is the key to such gene introgressions. This

process is relatively easy in diploid cereals. On the other hand, the hexaploid wheat

has three genomes and there is genetic control of chromosome pairing so that only

homologous partners pair to form bivalents. Thus, wheat (both bread wheat and durum

wheat) has a homologous pairing suppressor gene, Ph1, which ensures diploid-like

chromosome pairing and hence disomic inheritance. These characteristics are essential

for the meiotic and reproductive stability of wheat. However, Ph1 does not permit

pairing between the wheat and alien chromosomes, thereby impeding alien gene

transfer. Methods of suppressing the activity of Ph1 and hence promoting wheat-alien

chromosome pairing are known (JAUHAR and CHIBBAR, 1999).

Through wide hybridization coupled with manipulation of chromosome pairing,

several desirable genes have been incorporated into wheat (JAUHAR and CHIBBAR,

1999). Thus, genes for resistance to leaf rust and barley yellow dwarf virus have been

transferred from Agropyron, Thinopyrum and Aegilops into wheat. JAUHAR and

PETERSON (2000) produced scrab-resistant durum wheat germplasm by transferring

in it segments of chromosomes from Thinopyrum junceiforme.

A better understanding of the factors limiting practical exploitation of exotic

germplasm promise to transform existing, and accelerate the development of new,

strategies for efficient and directed germplasm utilization (FEUILLET et al., 2008).

Plant protoplasts were an attractive target for transformation during the 1980s as it

was already known that plants could be regenerated from protoplasts and that DNA

could be introduced into them by electroporation or by osmotic shock (by

polyethylene glycol treatment). These methods are technically simple and inexpensive,

often resulting in thousands of transformed micro-colonies in one experiment, with the

possibility of producing many independent transformants. However, cell suspension

cultures used for protoplast isolation are highly genotype-dependent, often prone to

somaclonal variations and have a time-limited morphogenic competence. These

disadvantages have restricted full use of the protoplast-based transformation

technology, and the interest for the technique has declined for most cereals

(REPELLIN et al., 2001; VASIL, 2007). Although production of stably transformed

cell lines of T. monococcum as well as T. aestivum was described (Muller et al. 1996),

none of these transformed lines were regenerated into plants. Neither the fertility of

the plants, nor the transmission of the transgenes to progeny, was demonstrated on the

rare occasions when plants were regenerated from transformed protoplasts (He et al.

1994).

During the past quarter century the unique and natural ability of the soil-borne

crown gall bacterium- Agrobacterium tumefaciens- to transfer and integrate DNA into

the genome of wounded intact plant cells has been exploited extensively for the

genetic transformation of higher plants (Fig. 2). Although Agrobacterium as a

phytopathogen is known to have an exceptionally wide host range, it does not

generally infect monocots, particularly the economically important cereal crops. Its

inability to infect monocots in nature was the main reason for the widely accepted

wisdom of the time that Agrobacterium could not be used to transform cereals. This

created the need to find alternative methods of transformation and led to the now

32 Šramková, Z. et al.

universally-held view that embryogenic cultures are the best, and perhaps the only,

source of regenerable cells in the Poaceae (JAUHAR, 2006; LAKSHMAN, 2006).

Fig. 2. Approaches usable in genetic improvement of wheat. A: Agrobacterium-mediated transformation, B:

biolistic method (www.ag.ndsu.edu/pubs/plantsci/crops/a1219-2.gif).

One reason for the delay in cereal transformation by Agrobacterium was the weak,

or lack of woundresponse, from injured cereal tissues. The difficulties were overcome

by co-cultivation of actively dividing embryogenic cells with supervirulent strains of

Agrobacterium tumefaciens in the presence of acetosyringone, a potent inducer of

virulence genes (SHRAWAT and LORZ, 2006).

The most commonly used method to deliver DNA into plant tissues and callus is

the high velocity bombardment of DNA- coated microprojectiles (biolistics) (Fig. 2).

This technology of direct DNA delivery, developed by SANFORD et al. (2000),

overcame many of the problems inherent in the use of protoplasts. It rapidly became

the method of choice for the transformation of cereals, particularly wheat (VASIL and

VASIL, 2006). For optimal efficiency, a balance between the penetration power of the

particles and the intensity of the wounds created in the target tissues must be attained.

Transgenic plants of wheat were produced for the first time in 1992, by the

bombardment of embryogenic callus tissues with the plasmid pBARGUS, in which the

expression of the GUS reporter gene is driven by the maize Adh1 promoter attached to

Adh 1 intron 1, and the expression of the selectable bar gene which confers resistance

to the broad-spectrum herbicide Basta is driven by the CaMV35S promoter attached to

the maize Adh1 intron 1 (VASIL et al., 1992). Further improvements in production of

transgenic wheat plants were obtained by using other types of plasmids and promoters.

Although the transgenes are integrated at various sites in the genome, they do not

cause any detectable chromosomal rearrangements, and their expression is more a

function of the promoters used rather than the site of integration (VASIL, 2007).

Nova Biotechnologica 9-1 (2009) 33

Agrobacterium-based systems and biolistic methods share common features. The

same explant tissues can be used as targets, the transformation frequencies are

comparable (STOGER et al., 1998), and both techniques are genotype-dependent

(LEE et al., 1999). However, the perceived disadvantages of particle bombardment

compared to Agrobacterium-mediated transformation, i.e., the tendency to generate

large transgene arrays containing rearranged and broken transgene copies, are not

borne out by the recent detailed structural analysis of transgene loci produced by each

of the methods. There is also little evidence for major differences in the levels of

transgene instability and silencing when these transformation methods are compared in

agriculturally important cereals (ALTPETER et al., 2005a)

It is also important to keep in mind that one of the serious problems associated

with Agrobacterium-based transformation is the frequent vector backbone integration

in transgenic lines of wheat and other plants, which is a serious impediment to gaining

regulatory approval for environmental release (WU et al., 2006). Irrespective of the

method of transformation used, the transgenes are integrated at random sites in the

host genome that may sometimes cause position effects, gene silencing, etc. Site-

specific recombination has been proposed as a solution to this problem in wheat

(SRIVASTAVA et al., 1999). This technology also allows the removal of the

selectable marker gene.

4. Herbicide, pathogen and pests resistance

Weeds compete with crop plants for available nutrients and light energy, and thus

reduce crop yields. Actual worldwide crop losses to wheat productivity owing to

weeds are estimated to be 12.3%, but as high as 23.9% without crop protection

(OERKE et al., 1994). With widespread and long-term herbicide use, and the fact that

wheat has a single natural mechanism for degrading herbicides, many of the most

noxious weeds found in wheat fields have over time developed resistances to the

commonly used selective herbicides by evolving a similar mechanism (GRESSEL,

1996). In general, production of herbicide-resistant crops has involved insertion of

only one or two genes that encode inactivation of the herbicide by any of the following

three mechanisms: (i) overproduction of a herbicide-sensitive biochemical target, (ii)

structural alteration in biochemical target resulting in altered binding to the herbicide,

or (iii) detoxification or degradation of the herbicide, before it reaches its target site in

the plant cell (REPELLIN et al., 2001).

Glyphosate is the active ingredient of herbicide Roundup®. Glyphosate-tolerant

wheat plants were obtained showing in field trials neither any vegetative nor

reproductive damage, nor any reduction in yield (ZHOU et al., 2003). Recent

advances have focused on development of highly efficient detoxifying enzyme that

allows plants to resist glyphosate and provide improved protection against weeds when

incorporated into wheat (JOHANNES and ZHAO, 2006). Metabolic inactivation has

been used as a powerful and effective tool in engineering tolerance to the non-

selective, broad-spectrum, post-emergent, contact herbicides commonly known as a

Basta, Bialaphos, Herbiace and Glufosinate (VASIL, 1996). They provide a high

degree of human and environmental safety because they are non-toxic and are rapidly

34 Šramková, Z. et al.

biodegraded, resulting in minimal residue persistence in soil. Their herbicidal activity

is due to L-phosphinothricin (PPT), a potent inhibitor of the biosynthetic enzyme

glutamine synthetase (GS), which is involved in general nitrogen metabolism in plants.

PPT is inactivated by the acetylating enzyme phosphinothricin- N-acetyltransferase

(PAT). Two similar genes, bar and pat, that encode PAT, have been identified, cloned

and used to transform wheat, thus making the transgenic wheat immune to PPT and

making it possible to use Basta for effective weed control in wheat fields. The

transgene is transmitted to progeny in a Mendelian fashion and has been shown to be

stable under field conditions (VASIL, 2007).

A large number of fungal (such as rust caused by Puccinia spp., smut and bunt

caused by Tilletia and Ustilago spp., blotch caused by Septoria spp., Fusarium

blight/scab, Helminthosporium leaf blight, powdery mildew caused by Blumeria

graminis, etc.), bacterial (such as leaf streak caused by Xanthomonas translucens) and

more than 50 viral diseases are known to cause considerable worldwide damage to

wheat production (CURTIS et al., 2002). Losses of wheat production owing to

pathogens are estimated to be 12,4%, but as high as 16.7% without crop protection

(OERKE et al., 1994). Only limited protection against pathogens can be achieved by

chemical treatments or cultural practices (CURTIS et al., 2002). Resistance breeding

is a continuing and difficult process as resistance in most cases appears to be under

polygenic control, and even when resistant cultivars are developed, they do not

provide long-term relief due to ever-evolving or mutating pathogens (FRIESEN et al.,

2006).

Only modest progress has been made in engineering resistance to major fungal and

viral pathogens of wheat. In an early study, the coat protein gene of barley yellow

mosaic virus was introduced into wheat but no information was provided about its

effect on protection from any pathogens (KARUNARATNE et al., 1996.). However,

transgenic plants expressing the rnc70 gene expressing a mutant bacterial ribonuclease

III showed a high level of resistance to barley stripe mosaic virus (ZHANG et al.,

2001). Wheat plants transformed with the viral replicase gene Nib or the coat protein

gene of wheat streak mosaic virus showed a high level of resistance to inoculations

with two strains of the virus, had milder symptoms and lower virus titer than the

control plants but did not provide field resistance to the virus and yielded less than

their parent cultivars (SHARP et al., 2002).

The pinA gene could be considered as a potential and effective for the control of a

wide range of plant pathogens by genetic engineering. LUO et al. (2008) produced

transformed durum wheat cultivars expressing the PINA protein (puroindoline

protein), which has been shown to have antimicrobial and antifungal activity.

Transgenic plants showed enhanced response to leaf rust in greenhouse and field.

Transgenic wheat plants stably expressing an antifungal barley seed class II

chitinase gene (pr3) showed increased resistance to powdery mildew, but even more

significant protection was obtained with the introduction of the gene for an apoplastic

ribosome-inactivation protein (RIP) from barley (YAHIAOUI et al., 2006). The

expression of genes for an antifungal protein from Aspergilus giganteum and a barley

class II chitinase were shown to significantly reduce the formation of powdery mildew

and leaf rust (OLDACH et al., 2001). ALTPETER et al. (2005b) found enhanced

Nova Biotechnologica 9-1 (2009) 35

resistance against powdery mildew in wheat plants over-expressing the defence-related

TaPERO peroxidase gene in shoot epidermis.

Expression of the antifungal protein KP4 from Ustilago maydis-infecting virus

resulted in increased endogenous resistance against stinking smut. Partial protection

against Fusarium head blight has been reported in wheat plants expressing the F.

sporotrichioides gene FsTRI101 (VASIL, 2007).

Much work still needs to be done to produce wheat lines that are resistant to

various pathogens that cause major losses in productivity. The mapping of the leaf rust

resistance gene Lr10, of Fhb1, a major gene controlling Fussarium head blight

resistance (CUTHBERT et al., 2006; CHEN et al., 2007), and the identification and

characterization of the stripe rust resistance gene Yr34 should help in the isolation and

sequencing of the relevant genes that can be of much use in the development of

resistant varieties through marker-assisted breeding as well as genetic transformation

(CUTHBERT et al., 2006; LIN and CHEN, 2008; ŠLIKOVÁ et al., 2009).

Actual worldwide crop losses to wheat productivity owing to a variety of pests

(aphids, Hessian fly, locusts, beetles, moths, etc.) are estimated to be 9,3%, but as high

as 11,3% without crop protection (OERKE et al., 1994). Pests-resistant crops are

expected to increase crop yields and also to reduce the amount of agrochemicals used

for crop protection. Pests cause additional losses during post-harvest storage.

Unfortunately, research on introduction of pest resistance genes into wheat has so far

been very limited, because breeding for these traits is time consuming and does not

provide long-term protection as the pests develop biotypes which are able to overcome

the resistance genes. Future work should explore the possible benefits of introducing

resistance genes from related as well as unrelated species, such as the recent

characterization and expression study of a novel wheat gene (Hfr-3) encoding a

putative chitin-binding lectin that is associated with resistance against Hessian fly, a

major pest that causes considerable damage (GIOVANINI et al., 2007).

ALTPETER et al. (1999) introduced the barley trypsin inhibitor CMe (BTI-CMe)

into wheat. Expression and functional integrity of BTI-CMe in transgenic seed were

demonstrated, along with a significant reduction in the survival of the Angoumois

grain moth (Sitotroga ceralella), a major pest of stored wheat grain, reared on

transgenic seed expressing BTI-CMe. Similarly, wheat plants expressing the gene

encoding snowdrop lectin (Galanthus nivalis agglutinin: GNA) have been shown to

decrease the fecundity, but not the survival, of the grain aphid Sitobion avenae

(REPELLIN et al., 2001). AKHTAR et al. (2008) conducted experimental trials to

evaluate the resistance of host wheat plants against Rhopalosiphum padi L. (aphid) and

only one variety V-9021 was found to show the highest level of resistance.

5. Abiotic stress tolerance

Abiotic stresses (drought, salinity, flooding, excessively high or low temperatures,

high levels of minerals such as salt, heavy metals, etc.) cause adverse affects on plant

growth that can reduce crop productivity in wheat by more than 80% (BRAY et al.,

2000). So far the most successful approach to these problems has been to exploit

natural variation present either in the crop itself or in wild relatives (for example, salt

36 Šramková, Z. et al.

tolerance in Laphopyrum elongatum, aluminium tolerance in Aegilops uniarisfata).

Recent advances in understanding the genetic control of abiotic stress tolerance,

including the identification and coning of related genes, has encouraged research in

engineering plants that can tolerate these stresses without any negative impact on their

yield (SEKI et al., 2003). Although drought and salt tolerant genes that are present in

germplasm of wheat and other crops have been successfully used to obtain stress-

tolerant varieties, breeding for stress tolerance is time labor-intensive and complicated

by the multigenic nature of stress tolerance and the need for the simultaneous selection

of the related genes as the elimination of the undesirable genes (VASIL, 2007).

Plants are known to respond to biotic as well as abiotic stresses by inducing stress-

responsive genes. Several stress-inducible genes and their products have been

identified (YAMAGUCHI and BLUMWALD, 2005). Manipulation of the

transcription of stress responsive genes is increasingly being used to enhance stress

tolerance, such as drought resistance and salt tolerance in rice (HU et al., 2006).

KAWAURA et al. (2008) found out, that approximately 19% of wheat genes are salt

responsive. Although salt-responsive genes of wheat were grouped into 12 groups

based on expression patterns, their functions in salt tolerance remain to be clarified.

Introduction of the ABA-responsive barley gene HVA1 into wheat improved

growth under soil-water deficit conditions. Further field evaluations of some of the

transgenic lines showed greater plant biomass and grain yield in plants expressing the

HVA1 gene in comparison to the non-transformed controls (BAHIELDIN et al., 2005).

Improved tolerance to salinity has been also reported in wheat plants expressing a

vacuolar Na+/H+ antiporter gene (HUANG et al., 2006).

Much more attention needs to be paid now to the development of wheat varieties

that can provide high yields under drought and at higher temperatures in saline soils

(UMEZAWA et al., 2006). PELEG et al. (2008a) performed a comprehensive survey

of wild emmer populations from across aridity gradient in Israel and revealed a wide

phenotypic and allelic diversity for drought response, demonstrating the potential of

the wild genepool for wheat improvement. These results exemplify the unique

opportunities to exploit favourable alleles that were excluded from the domesticated

genepool and may serve as a start point for introgression of promising QTLs into elite

cultivated materials via marker-assisted selection.

Improvement of frost tolerance (winter hardiness) is an important aim of wheat

breeding programs (DÖRFFLING et al., 2009). MILLER et al. (2006) have identified

several C-repeat-binding factors (CBF) located at the frost tolerance locus Fr-A’’’2 in

Triticum monococcum. These can be useful in heat improvement programs in regions

where considerable yield losses occur during severe winters.

In many parts of world, excessive deforestation causes frequent devastating floods

resulting in significant crop losses when plants are submerged in water for long

periods of time. Recently, Sub1A gene has been identified in rice and its

overexpression in a submergence-intolerant variety conferred enhanced submergence

tolerance to the plants (XU et al., 2006). It would be worthwhile to transfer this gene,

that is responsible for submergence tolerance in rice, into wheat by genetic

transformation to test if it will have a similar effect in wheat varieties that are grown in

flood-prone areas.

Nova Biotechnologica 9-1 (2009) 37

Natural genetic variability has been exploited to standing of aluminium tolerance

in wheat. However, further understanding of the genetic and physiological factors that

regulate aluminium tolerance is needed in order to develop a wider range of wheat

varieties with a high level of aluminium tolerance. Transgenic plants over-expressing

citrate synthase or malate dehydrogenase genes have been shown to enhance

aluminium tolerance (MAGALHAES, 2006). The gene (ALTM1) that regulates

aluminium tolerance in wheat has been identified (ZHOU et al., 2007).

6. Yield increasing

Yield of wheat can be improved by increasing seed number and/or weight, the

latter by increasing the amount of starch, which is the most abundant component

(more than 70% of seed weight) of wheat endosperm, or by regulation of endosperm

development. Starch synthesis in cereals is regulated by ADP-glucose

pyrophosphorylase (AGP), that is likely involved in determination of seed sink

strength (HANNAH and JAMES, 2008). SMIDANSKY et al. (2002) found that

transgenic lines expressing a modified maize Sh2 gene (Sh2r6hs), which encoded an

altered AGP large subunit, showed a 38% increase in seed weight/plant and a 31%

increase in total biomass. Seed weight of inferior spikelets can be improved in rice

panicle by increasing activities of starch synthesizing enzymes (MOHAPATRA et al.,

2009)

The number of tillers formed on each plant is among many factors that determine

yield in wheat (and in rice), by influencing the number and size of panicles and seeds

produced. MONOCULM1 (MOC1), a gene that controls tillering in rice, has been

identified (LI et al., 2003). Changing the architecture of the plant by the formation of

more tillers and leaves which are spread out (SAKAMOTO et al., 2006;

KURAPARTHY et al., 2007) would expose a larger leaf surface for the capture of

sunlight for increased photosynthesis, leading to improved productivity.

Genes that regulate the activity of the major plant hormones (gibberellins, auxins,

cytokinins and brassinosteroids) have been shown to be involved in dwarfing and

grain production (ASHIKARI et al., 2005; SAKAMOTO, 2006). The increasing

understanding of the genetic control of plant architecture (shoot branching, plant

height, inflorescence morphology, etc.), and the effect of phytohormones on yield is

expected to play a major role in the development of high yielding crops

(SAKAMOTO, 2006; WANG and LI, 2006).

The element silicon is present in significant but variable amounts in all plants. It

has many useful functions, including enhancing resistance to lodging, pests and

pathogens. The varied roles of the silicon transporter gene provide ‘‘a new strategy for

producing crops with high resistance to multiple stresses by genetic modification of

the root’s silicon uptake capacity’’ (MA et al., 2006).

The other possible approaches for yield improvement include: changing C3 wheat

into a C4 plant (which is much more efficient because of greatly reduced loss of

carbon by photorespiration) or the production of wheat hybrids (heterosis or hybrid

vigor has been used to obtain dramatic increases in crop yields for nearly 75 years,

most prominently in maize and recently also in rice) (WANG et al., 2005)

38 Šramková, Z. et al.

Regulation of flowering and its manipulation must remain an important part of the

overall strategy to improve wheat productivity. Several genes (VRN1, VRN2 and

VRN3) that have been shown to be involved in the vernalization response (the

requirement for a long period of exposure to low temperatures for flowering) in wheat

can be manipulated by RNA interference and other means to affect flowering time, or

to convert winter wheats to spring wheats (YAN et al. 2006).

7. Improvement of grain quality

For most traditional uses, wheat quality derives mainly from two interrelated

characteristics: grain hardness and protein content. Grain hardness is a heritable trait

but it can be strongly affected by abnormal weather conditions such as excessive

rainfall during the harvest period. Protein content is weakly heritable and strongly

dependent on environmental factors such as available soil nitrogen and moisture

during the growing season (BELDEROK et al., 2000). In addition, each end-use

requires a specific 'quality' in the protein. Durum wheat cultivars have the hardest

grain texture and are usually high in protein content. They are especially suited to the

production of pasta because of their highly vitreous grain (high milling yield of

semolina), unique combination of storage proteins for good cooking quality of pasta,

and high yellow pigment content required for attractive appearance of cooked product.

All three characteristics are highly heritable and can be readily improved by

conventional breeding. Recent research has shown that the presence of γ-gliadin 45 is

a reliable marker of good cooking quality. This marker is now used for screening early

generation material in many durum wheat breeding programs. Bread (also common or

hexaploid) wheats cover a wide range of grain hardness and protein content. The

hardest wheats of this class, generally highest in protein, are used for pan bread.

Common wheats of medium hardness and lower protein content are used for other

types of bread and noodles. Wheats with softest texture and lowest protein are used for

cakes and cookies. In some end-uses, e.g., Chinese-type noodles, starch quality is

important together with protein quality; this feature should be taken into consideration

in developing a screening strategy for wheats for this application. Screening tests that

reflect end-use requirements for most of the known products are available, and should

be applied in testing wheats according to intended use (BUSHUK, 1998).

An important factor, which affects negatively the grain quality, is sprouting. The

germination causes an increase in alpha amylase, an enzyme that breaks down starch.

Sprouting can affect food made from wheat in many ways. It can reduce mixing

strength, cause sticky dough, and affect loaf volume and shelf life. In pasta, sprouting

can reduce shelf life, increase cooking loss, and produce softer cooked pasta. Flour

damaged by alpha-amylase holds less water when mixed and the dough absorbs less

water during baking. “Falling number” gives an indication of the amount of sprout

damage that has occurred within a wheat sample. As the amount of enzyme activity

increases, the falling number decreases. Generally, a falling number value of 350

seconds or longer indicates a low enzyme activity and very sound wheat quality. As

the pre-harvest sprouting (PHS) of wheat greatly reduces the quality and economic

value of grain, PHS tolerance is one of the most important traits in wheat breeding.

Viviparous 1 (Vp1) gene of maize is known to encode a transcription factor VP1 that

Nova Biotechnologica 9-1 (2009) 39

controls seed germination. Hexaploid wheat possesses three Vp1 homoeologues

(TaVp1): TaVp-A1, TaVp-B1 and TaVp-D1. The sequence analyses of cDNAs

revealed that some of TaVp-A1 transcripts and TaVp-D1 transcripts are spliced

incorrectly, resulting in production of truncated or deleted proteins. Most TaVp-B1

transcripts are spliced correctly. The dual function of TaVP-B1 was confirmed: the

activation of Em expression (required for ABA-inducible expression) and the

repression of α-amylase expression (UTSUGI et al., 2008). Recently, a co-dominant

STS marker of Vp-B1 gene was developed and designated as Vp1B3. Statistical

analysis indicated that Vp1B3 was strongly associated with PHS tolerance in the set of

Chinese wheat germplasm, suggesting that Vp1B3 could be used as an efficient and

reliable co-dominant marker in the evaluation of wheat germplasm for PHS tolerance

and marker-assisted breeding for PHS tolerant cultivars (YANG et al., 2008; XIA et

al., 2009).

Among all the cereals, only the flour of hexaploid wheat (Triticum aestivum) is

able to form dough that exhibits the rheological properties required for the production

of leavened bread. This property results from the ability of wheat storage proteins,

gliadins and glutenins, to form special protein complex known as gluten. Biochemical

and genetic evidence has demonstrated that high molecular weight glutenin subunit

(HMW-GS) plays a major role in determining the viscoelastic properties thereby

determining bread making qualities. The HMW glutenins are necessary to create

strong dough, which is essential for making high quality, yeast-raised breads.

The HMW-GS are further subdivided into high Mr, x-type and low Mr, y-type

subunits. Two HMW-GS alleles, which are inherited as tightly linked pairs encoding

an x-type and a y-type subunit, are present at the Glu-1 locus on the long arms of the

homoeologous chromosomes 1A, 1B and 1D of all hexaploid bread wheat cultivars

(PAYNE, 1987). All cultivars of wheat, therefore, contain six HMW-GS genes, but

only three, four or five subunits, because some of the genes are silent; the 1Ay gene is

silent in all cultivars. HMW-GS may represent up to 10% of the total seed protein, as

each HMW-GS accounts for about 2% of the total extractable protein. The HMW-GS

alleles 1Ax1, 1Ax2* and the 1Dx5 + 1Dy10 subunit pair are said to be associated with

stronger doughs and better baking properties, and 1Dx2 + 1Dy12 pair with weaker

doughs (VASIL and ANDERSON, 1997). The number and composition of HMW-GS

present in a cultivar are closely related to the quality of its gluten or dough (PAYNE,

1987). Considerable progress has been achieved in research of the molecular

properties of flour proteins that are required for highest bread quality. Segregating

breeding populations can be screened by electrophoresis or high performance liquid

chromatography for the presence of desirable glutenin subunits. However, because of

the tight linkage of the HMW-GS alleles, it is quite difficult to manipulate them by

traditional breeding methods. Determination of technological quality of wheat

cultivars according to analysis of HMW-GS reveals a successful progress in Slovak

wheat breeding and its successes in creating cultivars with high bread-making quality.

This can be seen particularly by allele distribution at Glu-B1 and Glu-D1 loci where

HMW-GS having a negative impact on quality, mainly alleles at the Glu-B1 6+8 locus

and Glu-D1 2+12 locus, occur at a substantially lower rate than in West European

cultivars (GREGOVÁ et al., 2007; ŠRAMKOVÁ et al., 2008).

40 Šramková, Z. et al.

A number of HMW-GS as well as low-molecular-weight glutenin subunit (LMW-

GS) genes have been introduced into bread and pasta wheat by genetic transformation

(TOSI et al., 2005; BREGITZER et al., 2006; BLECHL et al., 2007). The HMW-GS

1Ax1 gene which is known to be associated with superior bread making quality was

introduced into the cultivar Bobwhite lacking this gene (ALTPETER et al., 1996). The

transgenic plants expressing the introduced HMW-GS were normal, fertile and showed

Mendelian segregation of the transgene. The effect of HMW glutenin subunits 1Ax1

and/or 1Dx5 on dough elasticity was demonstrated by introducing the corresponding

genes into durum wheat and Triticale; cereals with poor bread making properties.

Transgenic durum wheat producing one additional HMW glutenin, 1Ax1 or 1Dx5,

gave an increased dough strength and stability, thus changing the properties of durum

flour for both bread and pasta making (HE et al., 1999). ALVAREZ et al. (2000)

introduced the HMW-GS genes 1Ax1 and 1Dx5 into a commercial cultivar of T.

aestivum that already expresses five subunits. The overexpression of 1Dx5 gene

increases the contribution of the HMW-GS to a level of 22% of the total protein

content. However, the overexpression of the 1Dx5 gene was found to be associated

with a dramatic increase in dough strength by making it too strong, and, therefore,

unsuitable for use in conventional breadmaking (BLECHL et al., 2007).

Wheat landraces represent interesting biological material because of their genetic

variability. Some of them possess genes, not occurring in modern cultivars, although

these genes can be valuable for improvement of their quality. Thus, screening

landraces for the novel HMW-GS alleles for further utilization has become a part of

some breeding programs (GREGOVÁ et al., 1999; GREGOVÁ et al., 2004;

GREGOVÁ et al., 2006).

TOSI et al. (2005) reported the production of transgenic wheats expressing

additional LMW subunits in the commercial durum wheat varieties. The gene

constructs used in this work were derived from Glu-A3 and Glu-B3 loci. Expression

levels ranged up to those of the major endogenous LMW subunits. Their incorporation

into polymers was demonstrated. However, co-suppression of the major endogenous

HMW subunit was observed, leading to reduced dough strength in comparison with

line, which did not exhibit co-suppression, having increased strength.

Identification and characterisation of novel LMW-GS suggests that there is

intensive research in this area and improvement of wheat quality is in progress (AN et

al. 2006; ZHAO et al. 2006; ZHAO et al. 2007).

In near future, molecular approaches including genetic transformation and marker-

assisted selection will provide an opportunity for improving further the wheat

processing qualities by introduction of genes associated with good bread-making

qualities into a cultivar which is agronomically desirable but which has poor bread-

making qualities. This would avoid or minimize the necessity of blending flour from

different cultivars in milling operations.

8. Increasing of healthful components

Hunger and malnutrition are among the most devastating problems affecting

a large part of the world’s population. The nutritional value of wheat is extremely

Nova Biotechnologica 9-1 (2009) 41

important as it takes an important place among the few crop species being extensively

grown as staple food sources. The importance of wheat is mainly due to the fact that

its seed can be ground into flour, semolina, etc., which form the basic ingredients of

bread and other bakery products, as well as pastas, and thus it presents the main source

of nutrients such as proteins, carbohydrates, lipids, fibre and vitamins, to the most of

the world population. However, the total content or absolute concentration, of a given

nutrient in a food is not always a reliable indicator of its useful nutritional quality,

because not all of the nutrients is absorbed (PAREDES-LÓPEZ and OSUNA-

CASTRO, 2007). One of the continuing criticisms of modern crop varieties, that have

been commercialized thus far, is that although they do have many desirable attributes,

none of them offer any direct, tangible benefits to the consumer. This situation is

changing rapidly with increasing understanding of the molecular and genetic control of

various aspects of plant growth and development, which has made it possible to

enhance the quality as well as the quantity of proteins/starches/oils, and the content of

vitamins, essential amino acids, minerals and other healthful components of plants.

Although not much work of this nature has been carried out in wheat, there is no

reason why the success which has been achieved in crops such as rice, maize and

soybean, or demonstrated in model species such as Arabidopsis, cannot be extended to

wheat (VASIL, 2007).

Protein quality is based on their amino acid composition (particularly their relative

content of essential amino acids) and their digestibility. Therefore, high quality

proteins are those that are easily digested and contain the essential amino acids in

quantities that correspond to human requirements. Deficiency in certain amino acids

reduces the availability of others present in abundance. In general, cereal proteins are

low in lysine (1.5–4.5% vs. 5.5% of WHO recommendation), tryptophan (Trp, 0.8–

2.0% vs. 1.0%), and threonine (Thr, 2.7–3.9% vs. 4.0%). Because of this deficiency,

these essential amino acids (EAAs) become the limiting amino acids in cereals. It is

thus of economic and nutritional significance to enhance the EAAs in plant proteins.

In the past, plant geneticists and breeders have made much effort to improve the

quality of plant proteins. Natural mutations such as high-lysine corn and barley have

been identified and developed into elite genotypes (BRIGHT and SHEWRY, 1983).

Unfortunately, undesirable traits such as greater susceptibility to diseases and pests

and lower yields were associated with these mutations. The correlation between

nutritional quality and yield has been a serious issue over the years, since the two

factors appear to be negatively correlated. This problem appears to have been

overcome since the introduction of modifier genes (mo2 genes) that changed the

opaque-2 phenotype of the maize seed, thus allowing wild-type-like seed

characteristics to be maintained, resulting in normal yield but conserving the high

lysine and high tryptophan concentrations (GAZIOLA et al., 1999). These new maize

lines have been designated QPM (Quality Protein Maize) and several hybrids were

produced and introduced into the market. However, the widespread use of these

varieties has not been as fast as initially expected. Apart from the QPM lines, it would

appear that very little else in the way of high-lysine crops is available. Perhaps recent

legislation and general concern about the use of modified genetic organisms have been

the major setback regarding the release of such crops (FERREIRA et al., 2005).

42 Šramková, Z. et al.

For a long time there has been much interest in developing high-amylose wheat as

a source of resistant starch (RS), which is one of the major sources of dietary fiber and

its many related benefits (e.g., prevention of coronary heart disease, cancers of the

colon and rectum, diabetes) to humans. Suppression of starch branching enzyme II

(SBEIIa and SBEIIb) expression by RNA interference was used to produce high-

amylose wheat which was shown to be healthful for rats (REGINA et al., 2006).

The (1→3;1→4)-β-D-glucans, found exclusively in the cell walls of cereal and

grass species, are important components of dietary fiber and highly beneficial in the

prevention and treatment of serious human health conditions, including colorectal

cancer, high serum cholesterol and cardiovascular diseases, obesity and non-insulin-

dependent diabetes. β-D-Glucans were shown to have immunostimulating activity

(DALMO and BØGWALD, 2008). Genes responsible for (1→3;1→4)-β-D-glucan

synthesis in grasses have been identified and provide an excellent opportunity to

enhance the dietary fiber content of cereal and other food crops through transformation

(BURTON et al., 2006).

In attempting to enhance micronutrient levels in wheat through conventional plant

breeding, it is important to identify genetic resources with high levels of the targeted

compound, to consider the heritability of the targeted traits, to explore the availability

of high throughput screening tools and to gain a better understanding of genotype by

environment interactions (ORTIZ-MONASTERIO et al., 2007).

A well-known success of genetic transformation in cereals represents the

development of the golden rice. It was first engineered with the insertion of the PSY

gene from daffodil (Narcissus pseudonarcissus) and the bacterial phytoene desaturase

(CrtI) gene from Erwinia uredovora (YE et al., 2000). Bacterial CrtI can catalyze

three enzymatic steps from phytoene to all-trans-lycopene. The PSY gene is under the

control of an endosperm-specific glutelin promoter. To localize the product in plastids,

CrtI was designed as a fusion with the ribulose-1,5-bisphosphate

carboxylase/oxygenase (Rubisco) small subunit. An alternative construct was made by

co-transformation with constructs carrying the PSY/CrtI gene as described above and

the LCY gene under the control of a glutelin promoter. By the latter approach, the

carotenoid content of edible rice endosperm was 1.6 μg/g dry weight (YE et al., 2000).

However, in 2005, Golden Rice2 was developed and the carotenoid content was

increased up to 23- fold (37 μg/g of dry weight) compared to the original Golden Rice.

This content is close to a realistic level for palliating VAD (vitamin A deficiency) in

children (PAINE et al., 2005). Expression of carotenoid biosynthetic genes in other

cereals, such as wheat, requires further scientific investigation.

EHRENBERGEROVÁ et al. (2006) presented data indicating significant effects of

cropping system, genotype, and year grown on the tocol levels in barley. The results

suggest that a selective breeding program using the best genotypes would be beneficial

to produce food barleys with higher levels of total tocols and tocotrienols.

The International Maize and Wheat Improvement Center, along with its many

partners, has identified several maize and wheat varieties with 25% to 30% higher

grain iron and zinc concentrations. Wild relatives of wheat have been found to contain

some of the highest iron and zinc concentrations in the grains. Backcrossing to bread

Nova Biotechnologica 9-1 (2009) 43

wheat could result in highly nutritious cultivars (OZTURK et al., 2006; PELEG et al.,

2008b).

UAUY et al. (2006) have characterized and cloned Gpc-B1, a quantitative trait

locus from wild emmer wheat that is associated with increased levels of grain protein,

zinc and iron as a consequence of accelerated senescence and increased nutrient

mobilization from leaves to the developing grains. In ancestral wild wheat the allele

encodes a NAC transcription factor (NAM-B1), while only a non-functional NAM-B1

allele is present in modern cultivated wheat varieties. Silencing of the multiple NAM

homologues by RNA interference in transgenic plants caused delayed maturation and

reduced grain protein, iron and zinc content by more than 30%. The cloning of Gpc-B1

provides a direct link between the regulation of senescence and nutrient remobilization

and an entry point to characterize the genes regulating these two processes. This may

contribute to their more efficient manipulation in crops and translate into food with

enhanced nutritional value.

Phosphate, which is stored in the form of phytic acid in plant seeds (including

wheat), is indigestible in monogastric animals including humans due to the fact that

they lack phytases which degrade phytic acid in the digestive tract. Transgenic wheat

plants expressing the Aspergillus niger phytase encoding gene phyA accumulate

phytase in their seed (BRINCH-PEDERSEN et al., 2003; BRINCH-PEDERSEN et

al., 2006). Further improvement in the expression and thermostability of phytases in

transgenic wheat plants has the potential to increase the bioavailability of Zn2+, Ca2+

and Fe2+ by breaking down their otherwise indigestible complexes with phytic acid.

GUTTIERI et al. (2007) identified a wheat mutant (Lpa1-1) with reduced phytic acid

phosphorus and increased inorganic phosphorus (Pi). During germination there is

a large decrease in phytine, which can make up to 80% of the total phosphate found in

seeds (REDDY et al., 1982) and a concomitant increase of Pi suggesting that phytin

acts as a storage pool of phosphate during germination. Thus, it can be disputable

whether the phytine decrease could result in growth disorders of the wheat plant and

negatively affect all the metabolic reactions where phosphorus is a limiting factor

(biosynthesis of nucleic acids, phospholipids, proteins and other energy-generating

processes). However, genetically modified, low-phytic acid strains of maize having

approximately 35% of the phytic acid content of wilde-type maize (WTM), did not

exhibit substantial differences in growth as well as micronutrient and mineral

concentrations when compared to WTM. Moreover, absorption of iron from tortillas

prepared from transgenic maize was nearly 50% greater than from normal tortillas

(MENDOZA et al., 1998; SHI et al., 2005).

The world's agricultural community should adopt plant breeding and other genetic

technologies to improve human health, and the world's nutrition and health

communities should support these efforts. Sustainable solutions to the enormous

global problem of 'hidden hunger' will not come without employing agricultural

approaches (WELCH and GRAHAM, 2004.). Biofortification has the potential to

contribute to increased micronutrient intakes and improved micronutrient status. The

success of this strategy will require the collaboration between health and agriculture

sectors (HOTZ and McCLAFFERTY, 2007; CAKMAK, 2008).

44 Šramková, Z. et al.

References

AKHTAR, N., ANWAR, M. B., JILANI, G., JAVED, H. , YASMIN, S., BEGUM, I.:

Resistance to foliage feeding aphid in wheat. Pak. J. Biol. Sci., 11, 2008, 801-804.

ALTPETER, F., BAISAKH, N., BEACHY, R., BOCK, R., CAPELL, T., CHRISTOU,

P., DANIELL, H., DATTA, K., DATTA, S., DIX, P.J., FAUQUET, C., JUANY,

N., KOHLI, A., MOOIBROEK, H., NICHOLSON, L., NGUYEN, T.T.,

NUGENT, G., RAEMAKERS, K., ROMANO, A., SOMERS, D.A., STOGER, E.,

NIGEL, T., VISSER, R.: Particle bombardment and the genetic enhancement of

crops: myths and realities. Mol. Breed., 15, 2005a, 305-327.

ALTPETER, F., DIAZ ,I., MCAUSLANE, H., GADDOUR, K., CARBONERO, P.,

VASIL, I.K.: Increased insect resistance in transgenic wheat stably expressing

trypsin inhibitor CMe. Mol. Breed., 5, 1999, 53-63.

ALTPETER, F., VARSHNEY, A., ABDERHALDEN, O., DOUCHKOV, D.,

SAUTTER, C., KUMLEHN, J., DUDLER, R., SCHWEIZER, P.: Stable

expression of a defense-related gene in wheat epidermis under transcriptional

control of a novel promoter confers pathogen resistance. Plant. Mol. Biol., 57,

2005b, 271-283.

ALTPETER, F., VASIL, V., SRIVASTAVA, V., VASIL, I.K.: Integration and

expression of the high-molecular-weight glutenin subunit 1Ax1 into wheat. Nat.

Biotechnol., 14, 1996, 1155–1159.

ALVAREZ, J.B., D'OVIDIO, R., LAFIANDRA, D.: Comparison of allelic x-type

genes present at the Glu-D1 locus in bread wheat by PCR and sequence analysis of

their N-terminal domain. J. Genet. Breed., 51, 1997, 161-166.

AN, X., ZHANG, Q., YAN, Y., LI, Q., ZHANG, Y., WANG, A., PEI, Y., TIAN, J.,

WANG, H., HSAM, S.L., ZELLER, F.J.: Cloning and molecular characterization

of three novel LMW-i glutenin subunit genes from cultivated einkorn (Triticum

monococcum L.). Theor. Appl. Genet., 113, 2006, 383-95.

ANONYMOUS: Slovak National List of Released Varieties. AT Publishing,

Bratislava, 198, 2008, 25-26.

ASHIKARI, M., SAKAKIBARA, H., LIN, S., YAMAMOTO, T., TAKASHI, T.,

NISHIMURA, A., ANGELES, E.R., QIAN, Q., KITANO, H., MATSUOKA, M.:

Cytokinin oxidase regulates rice grain production. Science, 309, 2005, 741-745.

BAHIELDIN, A., MAFOUZ, H.T., EISSA, H.F., SALEH, O.M., RAMADAN, A.M.,

AHMED, I.A., DYER, W.E., EL- ITRIBY, H.A., MADKOUR, M.A.: Field

evaluation of transgenic wheat plants stably expressing the HVA1 gene for drought

tolerance. Physiol. Plant., 123, 2005, 421-427.

BELDEROK, B., MESDAG, H., DONNER, D. A.: Bread-Making Quality of Wheat.

Springer. p. 3. 2000.

BICAR, E., H., WOODMAN-CLIKEMAN, W., SANGTONG, V., PETERSON, J.

M., YANG, S. S., LEE, M., SCOTT, M. P. Transgenic maize endosperm

containing a milk protein has improved amino acid balance. Transgenic Res., 17,

2008, 59-71.

BLECHL, A., LIN, .J, NGUYEN, S., CHAN, R., ANDERSON, O.D., DUPONT,

F.M.: Transgenic wheats with elevated levels of Dx5 and/or Dy10 high molecular

Nova Biotechnologica 9-1 (2009) 45

weight glutenin subunits yield doughs with increased mixing strength and

tolerance. J. Cereal Sci., 45, 2007, 172-183.

BRAY, E.A., BAILEY-SERRES, J., WERETILNYK, E. Responses to abiotic stresses.

2000. In: BUCHANAN, B., GRUISSEM, W., JONES, R. (eds) Biochemistry and

molecular biology of plants. American Society of Plant Physiologists, Rockville,

pp. 1158-1203.

BREGITZER, P., BLECHL, A.E., FIEDLER, D., LIN, J., SEBESTA, P., DE SOTO,

J.F., CHICAIZA, O., DUBCOVSKY, J.: Changes in high molecular weight

glutenin subunit composition can be genetically engineered without affecting

wheat agronomic performance. Crop. Sci., 46, 2006, 1553-1563.

BRIGHT, S. W. J., SHEWRY. P. R.: Improvement of protein quality in cereals. CRC

Crit. Rev. Plant Sci., 1, 1983, 49-93.

BRINCH-PEDERSEN, H., HATZACK, F., SORENSEN, L.D., HOLM, P.B.:

Concerted action of endogenous and heterologous phytase on phytic acid

degradation in seed of transgenic wheat (Triticum aestivum L.). Transgen Res., 12,

2003, 649-659.

BRINCH-PEDERSEN, H., HATZACK, F., STOGER, E., ARCALIS, E.,

PONTOPIDAN, K., HOLM, P.B.: Heat-stable phytases in transgenic wheat

(Triticum aestivum L.): deposition pattern, thermostability, and phytate hydrolysis.

J. Agric. Food Chem., 54, 2006, 4624-4632.

BURTON, R.A., WILSON, S.M., HRMOVA, M., HARVEY, A.J., SHIRLEY, N.J.,

MEDHURST, A., STONE, B.A., NEWBIGIN, N.J., BACIC, A., FISCHER, G.B.:

Cellulose synthase-like CslF genes mediate the synthesis of cell wall (1,3;1,4)-β-D-

glucans. Science, 311, 2006, 1940-1942.

BUSHUK, W.: Wheat breeding for end-product use. Euphytica, 100, 1998, 137-145.

CAKMAK, I. Enrichment of cereal grains with zinc: Agronomic or genetic

biofortification? Plant Soil, 302, 2008, 1–17.

CURTIS, B.C., RAJARAM, S., MACPHERSON, H.G. (eds). Bread wheat. In:

Improvement and production. FAO Plant Production and Protection Series (FAO),

no. 30, Rome, Italy. 2002

CUTHBERT, P.A., SOMERS, D.J., THOMAS, J., CLOUTIER, S., BRULE-BABEL,

A.: Fine mapping Fhb1, a major gene controlling Fusarium head blight resistance

in bread wheat (Triticum aestivum L.). Theor. Appl. Genet., 112, 2006, 1465-1472.

DALMO, R.A., BØGWALD, J.: ß-glucans as conductors of immune symphonies. Fish

Shellfish Immunol., 25, 2008, 384-396.

DÖRFFLING, K., DÖRFFLING, H., LUCK, E.: Improved frost tolerance and winter

hardiness in proline overaccumulating winter wheat mutants obtained by in vitro-

selection is associated with increased carbohydrate, soluble protein and abscisic

acid (ABA) levels. Euphytica, 165, 2009, 545-556.

DUBČOVSKÝ, J., DVOŘÁK,, J.: Genome plasticity a key factor in the success of

polyploid wheat under domestication. Science, 316, 2007, 1862-1866.

DVOŘÁK,, J., LUO, M.-C., YANg, Z.-L., ZHANG, H.-B.: The structure of the

Aegilops tauschii genepool and the evolution of hexaploid wheat. Theor. Appl.

Gen., 97, 1998, 657-670.

EHRENBERGEROVÁ, J., BELCREDIOVA, N., PRYMA, J., VACULOVA, K.,

NEWMAN, C. W.: Effect of cultivar, year grown, and cropping system on the

46 Šramková, Z. et al.

content of tocopherols and tocotrienols in grains of hulled and hulless barley. Plant

Foods Hum. Nutr., 61, 2006, 145-150.

FAOSTAT: Food and agriculture organization of the United Nations

(http://www.faostat.fao.org/)

FERNANDES, M.I.B., ZANATTA, A.C.A., PRESTES, A.M., CAETANO, V.R.,

BARCELLOS, A.L., ANGRA, D.C., PANDOLFI, V.: Cytogenetics and immature

embryo culture at Embrapa Trigo breeding program: transfer of disease resistance

from related species by artificial resynthesis of hexaploid wheat (Triticum aestivum

L. em. Thell). Genet. Mol. Biol., 23, 2000, 1051-1062.

FERREIRA, R.R., VARISI, V.A., MEINHARDT, L.W., LEA, J.P., AZEVEDO, R.A.:

Are high-lysine cereal crops still a challenge? Braz. J. Med. Biol. Res., 38, 2005,

985-994.

FEUILLET, C., LANGRIDGE, P., WAUGH, R.: Cereal breeding takes a walk on the

wild side. Trends Genet., 24, 2008, 24-32.

FRIESEN, T.L., STUKENBROCK, E.H., LIU, Z., MEINHARDT, S., LING, H.,

FARIS, J.D., RASMUSSEN, J.B., SOLOMON, P.S., MCDONALD, B.A.,

OLIVER, R.P.: Emergence of a new disease as a result of interspecific virulence

transfer. Nat. Genet., 38, 2006, 953-956.

GAZIOLA, S.A., ALESSI, E.S., GUIMARÃES, P.E.O., DAMERVAL, C.,

AZEVEDO, R.A.: Quality protein maize: a biochemical study of enzymes

involved in lysine metabolism. J. Agric. Food Chem., 47, 1999, 1268-1275.

GIOVANINI, M.P., SALTZMANN, K.D., PUTHOFF, D.P., GONZALO, M., OHM,

H.W., WILLIAMS, C.E.: A novel wheat gene encoding a putative chitin-binding

lectin is associated with resistance against Hessian fly. Mol. Plant Pathol., 8, 2007,

69-82.

GREGOVÁ, E., HERMUTH, J., KRAIC, J., DOTLAČIL, L.: Protein heterogeneity in

European wheat landraces and obsolete cultivars. Gen. Res. Crop Evol., 46, 1999,

521-528.

GREGOVÁ, E., HERMUTH, J., KRAIC, J., DOTLAČIL, L.: Protein heterogeneity in

European wheat landraces and obsolete cultivars: Additional information. Gen.

Res. Crop Evol., 51, 2004, 569-575.

GREGOVÁ, E., HERMUTH, J., KRAIC, J., DOTLAČIL, L.: Protein heterogeneity in

European wheat landraces and obsolete cultivars: Additional information II. Gen.

Res. Crop Evol., 53, 2006, 867-871.

GREGOVÁ, E., MIHÁLIK, D., ŠLIKOVÁ, S, ŠRAMKOVÁ, Z.: Allelic variation of

HMW glutenin subunits and 1BL.1RS translocation in Slovak common wheats.

Cereal Res. Comm, 35, 2007, 1675-1683.

GRESSEL, J.: The potential roles for herbicide-resistant crops in world agriculture.

1996. In: Duke, S.O. (ed) Herbicide-resistant crops. CRC Press, Boca Raton, 231-

250.

GUTTIERI, M.J., PETERSON, K.M., SOUZA, E.J.: Nutritional and baking quality of

low phytic acid wheat. In: BUCK, H.T. (ed) Wheat Production in Stressed

Environments, 2007, 487-493.

HANNAH, L.C., JAMES, M.: The complexities of starch biosynthesis in cereal

endosperms Curr. Opin. Biotechnol., 19, 2008, 160-165.

Nova Biotechnologica 9-1 (2009) 47

HE, D.G., MOURADOV, A., YANG, Y.M., MOURADOVA, E., SCOTT, K.J.:

Transformation of wheat (Triticum aestivum L.) through electroporation of

protoplasts. Plant Cell. Rep., 14, 1994, 192-196.

HE, G.Y., ROOKE, L., STEELE, S., BEKES, F., GRAS, P., TATHAM, A.S., FIDO,

R., BARCELO, P., SHEWRY, P.R., LAZZERI, P.A.: Transformation of pasta

wheat (Triticum durum L. var. durum) with high-molecular- weight glutenin sub-

unit genes and modification of dough functionality. Mol. Breed., 5, 1999, 377-379.

HEDDEN, P.: The genes of the Green Revolution. Trends Genet., 19, 2003, 5-9.

HOTZ, C., McCLAFFERTY, B.: From harvest to health: challenges for developing

biofortified staple foods and determining their impact on micronutrient status.

Food Nutr. Bull., 28, 2007, S271-S279.

HU, H., DAI, M., YAO, J., XIAO, B., LI, X., ZHANG, Q., XIONG, L.:

Overexpressing a NAM, ATAF, and CUC (NAC) transcription factor enhances

drought resistance and salt tolerance in rice. Proc. Natl. Acad. Sci. USA, 103,

2006, 12987-12992.

HUANG, S., SPIELMEYER, W., LAGUDAH, E.S., JAMES, R.A., PLATTEN, J.D.,

DENNIS, E.S., MUNNS, R.: A sodium transporter (KHT7) is a candidate for

Nax1, a gene for salt tolerance in durum wheat. Plant Physiol., 142, 2006, 1718-

1727.

CHEN, X., FARIS, J.D., HU, J., STACH, R.W., ADHIKARI, T., ELIAS, E.M.,

KIANIAN, S.F., CAI, X.: Saturation and comparative mapping of a major

Fusarium head blight resistance QTL in tetraploid wheat. Mol. Breed., 19, 2007,

113-124.

IGC: http://www.igc.org.uk/; 2008

JAUHAR, P. P., CHIBBAR, R. N.: Chromosome-mediated and direct gene transfers

in wheat, Electr. J. Biotech., 4, 2001, 570-583.

JAUHAR, P.P.: Modern biotechnology as an integral supplement to conventional plant

breeding: the prospects and challenges. Crop Sci., 46, 2006, 1841-1849.

JAUHAR, P.P., CHIBBAR, R.N.: Chromosome-mediated and direct gene transfers in

wheat. Genome, 42, 1999, 570-583.

JAUHAR, P.P., PETERSON, T.S.: Hybrids between durum wheat and Thinopyrum

junceiforme: Prospects for breeding for scab resistance. Euphytica, 118, 2000, 127-

136.

JOHANNES, T.W., ZHAO, H.: Directed evolution of enzymes and biosynthetic

pathways. Curr. Opin. Microbiol., 9, 2006, 261-267.

KARUNARATNE, S., SOHN, A., MOURADOV, A., SCOTT, J., STEINBISS, H.,

SCOTT, K.J.: Transformation of wheat with the gene encoding the coat protein of

barley yellow mosaic virus. Aust. J. Plant. Physiol., 23, 1996, 429-435.

KAWAURA, K., MOCHIDA, K., OGIHARA, Y.: Genome-wide analysis for

identification of salt-responsive genes in common wheat. Funct. Integr. Genomics,

8, 2008, 277-286.

KURAPARTHY, V., SOOD, S., DHALIWAL, H.S., CHHUNEJA, P., GILL, B.S.:

Identification and mapping of a tiller inhibition gene (tin3) in wheat. Theor. Appl.

Genet., 114, 2007, 286-294.

LAKSHMAN, P.: Somatic embryogenesis in sugarcane. In Vitro Cell Dev. Biol. Plant,

42, 2006, 201-205.

48 Šramková, Z. et al.

LEE, S.H., SHON, Y.G., LEE, S.I., KIM, C.Y., KOO, J.C., LIM, C.O., CHOI, Y.J.,

HAN, C.D., CHUNG, C.H., CHOE, Z.R., CHO, M.J.: Cultivar variability in the

Agrobacterium-rice cell interaction and plant regeneration. Physiol. Plantarum,

107, 1999, 338-345.

LIN, F., CHEN, X., M.: Quantitative trait loci for non-race-specific, high-temperature

adult-plant resistance to stripe rust in wheat cultivar Express. Theor. Appl. Genet.,

2008 (in press).

LUO, L., ZHANG, J., YANG, G., LI, Y., LI, K., HE, G.: Expression of puroindoline a

enhances leaf rust resistance in transgenic tetraploid wheat. Mol. Biol. Rep., 35,

2008, 195-200.

MA, J.F., TAMAI, K., YAMAJI, N., MITANI, N., KONISHI, S., KATSUHARA, M.,

ISHIGURO, M., MURATA, Y., YANO, M.: A silicon transporter in rice. Nature,

440, 2006, 688-691.

MAGALHAES, J.V.: Aluminum tolerance genes are conserved between monocots

and dicots. Proc. Natl. Acad. Sci. USA, 103, 2006, 9749-9750.

MENDOZA, C., VITERI, F.E., LONNERDAL, B., YOUNG, K.A., RABOY, V.,

BROWN, K.H.: Effect of genetically modified, low-phytic acid maize on

absorption of iron from tortillas Am. J. Clin. Nutr., 68, 1998, 1123-1127.

MEREZHKO, A. F.: Impact of plant genetic resources on wheat breeding. Euphytica,

100, 1998, 295-303.

MILLER, A.K., GALIBA, G., DUBCOVSKY, J.: A cluster of 11 CBF transcription

factors is located at the frost tolerance locus Fr-Am2 in Triticum monococcum.

Mol. Genet. Genomics, 275, 2006, 193-203.

MOHAPATRA, P.K., SARKAR, R.K., KUANAR, S.R.: Starch synthesizing enzymes

and sink strength of grains of contrasting rice cultivars. Plant Sci., 176, 2009, 256-

263.

MULLER, E., LORZ, H., LUTTICKE, S.: Variability of transgene expression in

clonal cell lines of wheat. Plant Sci., 114, 1996, 71-82.

OERKE, E.-C., DEHNE, H.-W., SCHONBECK, F., WEBER, A.: Crop production

and crop protection. Elsevier, Amsterdam, 1994.

OLDACH, K.H., BECKER, D., LORZ, H.: Heterologous expression of genes

mediating enhanced fungal resistance in transgenic wheat. Mol. Plant Microbe

Interact., 14, 2001, 832-838.

ORTIZ-MONASTERIO, J. I., PALACIOS-ROJAS, N., MENG, E., PIXLEY, K.,

TRETHOWAN, R., PEÑA, R.J.: Enhancing the mineral and vitamin content of

wheat and maize through plant breeding. J. Cereal Sci., 46, 2007, 293-307.

OZTURK, L., YAZICI, M. A., YUCEL, C., TORUN, A., CEKIC, C., BAGCI, A.,

OZKAN, H., BRAUN, H.-J., SAYERS, Z., CAKMAK, I.: Concentration and

localization of zinc during seed development and germination in wheat. Physiol.

Plant, 128, 2006, 144-152.

PAINE, J.A., SHIPTON, C.A., CHAGGAR, S., HOWELLS, R. M., KENNEDY, M.

J., VERNON, G., WRIGHT, S. Y., HINCHLIFFE, E., ADAMS, J. L.,

SILVERSTONE, A. , DRAKE, R.: Improving the nutritional value of Golden Rice

through increased pro-vitamin A content. Nat. Biotechnol., 23, 2005, 482-487.

PAREDES-LÓPEZ, O., OSUNA-CASTRO, J.A.: Molecular biotechnology for

nutraceutical enrichment of food crops: The case of micronutrients. In: SHETTY,

Nova Biotechnologica 9-1 (2009) 49

K., PALIYATH, G., POMETTO, A.L., LEVIN, R.E. (eds): Functional foods and

biotechnology. CRC Press, Boca Raton, 650, 2006, 97-132.

PAYNE, P.I. Genetics of wheat storage proteins and the effect of allelic variation on

bread-making quality. Annu. Rev. Plant Physiol., 38, 1987, 141-153.

PELEG, Z., SARANGA, Y., KRUGMAN, T., ABBO, S., NEVO, E., FAHIMA, T.:

Allelic diversity associated with aridity gradient in wild emmer wheat populations.

Plant. Cell Environ., 31, 2008a, 39-49.

PELEG, Z., SARANGA, Y., YAZICI, A., FAHIMA, T., OZTURK, L., CAKMAK, I.:

Grain zinc, iron and protein concentrations and zinc-efficiency in wild emmer

wheat under contrasting irrigation regimes. Plant Soil, 306, 2008b, 57-67.

REDDY, N.R., SATHE, S.K., SALINKE, D.P.: Phytates in legumes and cereals. Adv.

Food Res., 28, 1982, 1-92.

REGINA, A., BIRD, A., TOPPING, D., BOWDEN, S., FREEMAN, J., BARSBY, T.,

KOSAR- HASHEMI, B., LI, Z., RAHMAN, S., MORELL, M. K.: High-amylose

wheat generated by RNA interference improves indices of largebowel health in

rats. Proc. Natl. Acad. Sci. USA, 103, 2006, 3546-3551.

REPELLIN, A., BÅGA, M., JAUHAR, P.P., CHIBBAR, R.N.: Genetic enrichment of

cereal crops via alien gene transfer: New challenges. Plant Cell Tissue Organ Cult.,

64, 2001, 159-183.

SAKAMOTO, T.: Phytohormones and rice crop yield: strategies and opportunities for

genetic improvement. Transgen Res., 15, 2006, 399-404.

SAKAMOTO, T., MORINAKA, Y., OHNISHI, T., SUNOBARA, H., FUJIOKA, S.,

UEGUCHI-TANAKA, M., MIZUTANI, M., SAKATA, K., TAKATSUTO, S.,

YOSHIDA, S., TANAKA, H., KITANO, H., MATSUOKA, M.: Erect leaves

caused by brassinosteroid deficiency increase biomass production and grain yield

in rice. Nat. Biotechnol., 24, 2006, 105-109.

SANFORD, J.C.: The development of the biolistics process. In Vitro Cell Dev. Biol.

Plant, 36, 2000, 303-308.

SEKI, M., KAMEI, A., YAMAGUCHI-SHINOZAKI, K., SHINOZAKI, K.:

Molecular responses to drought, salinity and frost: common and different paths for

plant protection. Curr. Opin. Biotechnol., 14, 2003, 1945-1999.

SHARP, G.L., MARTIN, J.M., LANNING, S.P., BLAKE, N.K., BREY, C.W.,

SIVAMANI, E., QU, R., TOLBERT, L.E.: Field evaluation of transgenic and

classical sources of wheat streak mosaic virus resistance. Crop Sci., 42, 2002, 105-

110.

SHI, J., WANG, H., HAZEBROEK, J., ERTL, D.S., HARP, T.: The maize low-phytic

acid 3 encodes a myo-inositol kinase that plays a role in phytic acid biosynthesis in

developing seeds. Plant J., 42, 2005, 708-719.

SHRAWAT, A.K., LORZ, H.: Agrobacterium-mediated transformation of cereals: a

promising approach crossing barriers. Plant Biotechnol. J., 4, 2006, 575-603.

SMIDANSKY, E.D., MARTIN, J.M., HANNAH, L.C., FISCHER, A.M., GIROUX,

M.J.: Seed yield and plant biomass increases in rice are conferred by deregulation

of endosperm ADP-glucose pyrophosphorylase. Planta, 216, 2003, 656-664.

SRIVASTAVA, V., ANDERSON, O.D., OW, D.W.: Single-copy transgenic wheat

generated through the resolution of complex integration patterns. Proc. Natl. Acad.

Sci. USA, 96, 1999, 11117-11121.

50 Šramková, Z. et al.

STOGER, E., WILLIAMS, S., KEEN, D., CHRISTOU, P.: Molecular characteristics

of transgenic wheat and the effect on transgene expression. Transgenic Res., 7,

1998, 463-471.

ŠLIKOVÁ, S., ŠUDYOVÁ, V., MARTINEK, P., POLIŠENSKÁ, I., GREGOVÁ, E.,

MIHÁLIK, D.: Assessment of infection in wheat by Fusarium protein equivalent

levels. Eur. J. Plant Pathol., 2009 (in press).

ŠRAMKOVÁ, Z., GREGOVÁ, E., MEDVECKÁ, E., MIHÁLIK, D., ŠLIKOVÁ, S.:

Seed storage protein diversity in Slovak wheat cultivars In: PROHENS, J.,

BADENES, M.-L. (eds) Modern variety breeding for present and future needs:

proceedings of the 18th EUCARPIA general congress, 9-12 September 2008,

Valencia - Spain, 2008, 639.

TOSI, P., MASCI, S., GIOVANGROSSI, A., D’OVIDIO, R., BEKES, F.,

LARROQUE, O., NAPIER, J., SHEWRY, P.: Modification of the low molecular

weight (LMW) glutenin composition of transgenic durum wheat: effects on

glutenin polymer size and glulten functionality. Mol. Breed., 16, 2005, 113-126.

UAUY, C., DISTELFELD, A., FAHIMA, T., BLECHL, A., DUBCOVSKY, J. A:

NAC gene regulating senescence improves grain protein, Zn and Fe content in

wheat. Science, 314, 2006, 1298-1301.

UMEZAWA, T., FUJITA, M., FUJITA, Y., YAMAGUCHI-SHINOZAKI, K.,

SHINOZAKI, K.: Engineering drought tolerance in plants: discovering and

tailoring genes to unlock the future. Curr. Opin. Biotechnol., 17, 2006, 113-122.

UTSUGI S, NAKAMURA S, NODA K, MAEKAWA M.: Structural and functional

properties of Viviparous1 genes in dormant wheat. Genes Genet. Syst., 83, 2008,

153-166.

VARSHNEY, R. K., LANGRIDGE, P., GRANER, A.: Application of Genomics to

Molecular Breeding of Wheat and Barley. Advances in Genetics, 58, 2007, 121-

155.

VASIL, I. K.: Molecular genetic improvement of cereals: transgenic wheat (Triticum

aestivum L.). Plant Cell Rep., 26, 2007, 1133-1154.

VASIL, I.K.: The science and politics of plant biotechnology—a personal perspective.

Nat. Biotechnol.,21, 2003, 849-851.

VASIL, I.K., ANDERSON, O.D.: Genetic engineering of wheat gluten. Trends Plant

Sci., 2, 1997, 292-297.

VASIL, I.K., VASIL, V.: Transformation of wheat via particle bombardment, 2nd edn.

In: LOYOLA-VARGAS, V.M., VAZQUEZ-FLOTA, F. (eds) Methods in

molecular biology: plant cell culture protocols. Humana Press, Totowa, 318, 2006,

273-283.

VASIL, V., CASTILLO, A.M., FROMM, M.E., VASIL, I.K.: Herbicide resistant

fertile transgenic wheat plants obtained by microprojectile bombardment of

regenerable embryogneic callus. Biotechnology, 10, 1992, 667-674.

WANG, Y., LI, J.: Genes controlling plant architecture. Curr. Opin. Biotechnol., 17,

2006, 123-129.

WANG, Y., XUE, Y., LI, J.: Towards molecular breeding and improvement of rice in

China. Trends Plant Sci., 10, 2005, 611-614.

WELCH, R.M., GRAHAM, R.D.: Breeding for micronutrients in staple food crops

from a human nutrition perspective. J. Exp. Bot., 55, 2004, 353-64.

Nova Biotechnologica 9-1 (2009) 51

WU, H., SPARKS, C.A., JONES, H.D.: Characterization of T-DNA loci and vector

backbone sequences in transgenic wheat produced by Agrobacterium-mediated

transformation. Mol. Breed., 18, 2006, 195-208.

XIA, L.Q., YANG, Y., MA, Y.Z., CHEN, X.M., HE, Z.H., RÖDER, M.S., JONES,

H.D., SHEWRY, P.R.: What can the Viviparous-1 gene tell us about wheat pre-

harvest sprouting? Euphytica, 2009, (in press).

XU, K., XIA, X., FUKAO, T., CANLAS, P., MAGHIRANT-RODRIGUEZ, R.,

HEUER, S., ISMAIL, A.M., BAILEY- SEVRES, J., RONALD, P.C., MACKILL,

D.J.: Sub1A is an ethylene-response-factor-like gene that confers submergence

tolerance to rice. Nature, 442, 2006, 705-708.

YAHIAOUI, N., BRUNNER, S., KELLER, B.: Rapid generation of new powdery

mildew resistance genes after wheat domestication. Plant J., 47, 2006, 85-98.

YAMAGUCHI, T., BLUMWALD, E.: Developing salt-tolerant crop plants:

challenges and opportunities. Trends Plant Sci., 10, 2005, 615-620.

YAN, L., FU, D., LI, C., BLECHL, A., TRANQUILLI, G., BONAFEDE, M.,

SANCHEZ, A., VALARIK, M., YASUDA, S., DUBCOVSKY, J.: The wheat and

barley vernalization gene VRN3 is an orthologue of FT. Proc. Natl. Acad. Sci.

USA, 103, 2006, 19581-19586.

YANG, Y., ZHAO, X.-L., ZHANG, Y., CHEN, X.-M., HE, Z.H., YU, Z., XIA, L.-Q.:

Evaluation and Validation of Four Molecular Markers Associated with Pre-Harvest

Sprouting Tolerance in Chinese Wheats. Acta Agron. Sin., 34, 2008, 17-24.

YE, X., AL-BABILI, S., KLOTI, A., ZHANG, J., LUCCA, P., BEYER, P.,

POTRYKUS, I.: Engineering the provitamin A (beta-carotene) biosynthetic

pathway into (carotenoid- free) rice endosperm. Science, 287, 2000, 303-305.

ZHANG, L., FRENCH, R., LANGENBERG, W.G., MITRA, A.: Accumulation of

barley stripe mosaic virus is significantly reduced in wheat plants expressing a

bacterial ribonuclease. Transgenic Res., 10, 2001, 13-19.

ZHAO, X.L., XIA, X.C., HE, Z.H., GALE, K.R., LEI, Z.S., APPELS, R., MA, W.:

Characterization of three low-molecular-weight Glu-D3 subunit genes in common

wheat. Theor. Appl. Genet., 113, 2006, 1247-59.

ZHAO, X.L., XIA, X.C., HE, Z.H., LEI, Z.S., APPELS, R., YANG, Y., SUN, Q.X.,

MA, W.: Novel DNA variations to characterize low molecular weight glutenin

Glu-D3 genes and develop STS markers in common wheat. Theor. Appl. Genet.,

114, 2007, 451-60.

ZHOU, H., BERG, J.D., BLANK, S.E., CHAY, C.A., CHEN, G., ESKELEN, S.R.,

FRY, J.E., HOI, S., HU, T., ISAKSON, P.J., LAWTON, M.B., METZ, S.G.,

REMPEL, C.B., RYERSON, D.K., SANSONE, A.P., SHOOK, A.L., STARKE,

R.J., TICHOTA, J.M., VALENTI, S.A.: Field efficacy assessment of transgenic

Roundup Ready wheat. Crop Sci., 43, 2003, 1072-1075.

ZHOU, L., BAI, G., MA, H., CARVER, B.F. Quantitative trait loci for aluminum

resistance in wheat. Mol. Breed.,19, 2007, 153–161.

... The crop has initially originated in Asia and parts of Africa. All the species belonging to the genus Triticum can be divided into three basic groups, each distinguished by the number of chromosomes in the generative and vegetative cells [18]. It is usually grown in temperate climates with an optimum growing temperature of 25ºC. ...
Techniques for the Enrichment of Micronutrients in Crops through Biofortification: A Review
Article
Full-text available
Feb 2018
Noor ul-Huda
Ambash Riaz
Ali Abbas
Shahid Raza
View
... Glutenins confer strength and elasticity to dough (Wieser, 2007). To improve the rheological properties of wheat flour, breeders selected varieties with genetic features promoting high protein and gluten content ( Sramková et al., 2009). As well as for its rheological properties, there is an increasing interest in studying gluten proteins because they are the main factor causing celiac disease, an autoimmune enteropathy. ...
Genetic and environmental factors affecting pathogenicity of wheat as related to celiac disease
Article
Jan 2013
J CEREAL SCI
Barbara Prandi
Paola Mantovani
Gianni Galaverna
Stefano Sforza
View
Baking quality and high molecular weight glutenin subunit composition of Emmer wheat, old and new varieties of bread wheat
Article
Jan 2012
ROM AGRIC RES
Petr Konvalina
Jana Bradova
Ivana Capouchova
Zdenek Stehno
J. Moudrý Sr
View

Project

Identification and characterization of new genes coding storage proteins in wheat

View project

Project

Therapeutic approaches in the therapy of resistant bacterial infections

Zuzana Sramkova

keywords: infectious diseases, gram-negative bacteria, antibiotics, resistance, CADD, metabolites, betalactam analogues, plant extract, endolysins

View project

Article

Chemical composition and nutritional quality of wheat grain-Review

January 2009

Deficiencies of micronutrients such as iron, zinc, and vitamin A ("hidden hunger") afflict over three billion people. Currently there is an increasing preference among consumers for foods that contain not only traditional nutrients but also provide other compounds that are beneficial to health and well-being. Food systems that feed the world must be changed in ways that will insure that... [Show full abstract]

Article

Wheat Varieties Released in Slovakia and their Bread-Making Quality

October 2009 · Cereal Research Communications

The main goal of our work was to determine the composition of high-molecular-weight glutenin subunits (HMW-GS) in 84 cultivars of common wheat (Triticum aestivum L.) origi-nating from eight European countries and registered in Slovakia. Eleven alleles and 18 allelic compositions were detected. The most frequent HMW-GS patterns were "Null", 7 + 9, 5 + 10 and "Null", 7 + 8, 5 + 10 which were... [Show full abstract]

Article

Diversity of seed storage proteins in common wheat ( Triticum aestivum L.)

July 2011 · Plant Genetic Resources

The objective of our study was to determine the composition of high-molecular weight-glutenin subunits (HMW-GS) in 120 cultivars of common wheat (Triticum aestivum L.). Fourteen alleles and 34 allelic compositions were detected using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The most frequent HMW-GS alleles at the Glu-A1, Glu-B1 and Glu-D1 loci were null (57.1%), 7+9 (43.3%)... [Show full abstract]

Article

Chemical composition and nutritional quality of wheat grain

January 2009 · Acta Chimica Slovaca

Discover more

Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

This publication is from a journal that may support self archiving.

Learn more

Last Updated: 18 Dec 17

GENETIC IMPROVEMENT OF WHEAT-A REVIEW

Discover the world's research

Recommendations