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Origin, History, and Genetic Improvement of the Snap Pea ( Pisum sativum L.)
Abstract
Introduction Genetics of Snap Peas Breeding Objectives Breeding Methods Traits of Special Concern Molecular Markers and Transformation Future Prospects Literature Cited
... A popular pea cultivated and consume is (Pisum sativum L. var. macrocarpon Ser.) due to persistence a bounded sugar and sweet flavor in edible pods (Myers et al.,2001).In addition, the sugar snap pea is devoid of fiber and inner pod and precocious harvested for fresh package market (McGee, 2012). Biostimulants are a new product classification on the market a variety of formulations that have a beneficials impact on a plant's vitality plant growth and development processes, as well as their consequences especially when plant under stress condition. ...
... Several historical landraces and cultivars have been preserved and available in gene-banks, such as in the Nordic Genetic Resource Center (NordGen) in Sweden and John Innes Centre in England (Hagenblad et al., 2014). Field/dry peas and vegetable peas are the two broad categories of pea types, and vegetable peas are further grouped into green/garden/shelling peas, snow peas, and snap/sugar peas (Myers et al., 2001). Currently, various types of peas are cultivated across the country, covering the areas from the southern tip of Sweden to near the polar circle (Vanhala et al., 2016;Carlson-Nilsson et al., 2021). ...
Estimating the allelic variation and exploring the genetic basis of quantitatively inherited complex traits are the two foremost breeding scenarios for sustainable crop production. The current study utilized 188 wrinkled vining pea genotypes comprising historical varieties and breeding lines to evaluate the existing genetic diversity and to detect molecular markers associated with traits relevant to vining pea production, such as wrinkled vining pea yield (YTM100), plant height (PH), earliness (ERL), adult plant resistance to downy mildew (DM), pod length (PDL), numbers of pods per plant (PDP), number of peas per pod (PPD), and percent of small wrinkled vining peas (PSP). Marker-trait associations (MTAs) were conducted using 6902 quality single nucleotide polymorphism (SNP) markers generated from the diversity arrays technology sequencing (DArTseq) and Genotyping-by-sequencing (GBS) sequencing methods. The best linear unbiased prediction (BLUP) values were estimated from the two-decades-long (1999–2020) unbalanced phenotypic data sets recorded from two private breeding programs, the Findus and the Birds eye, now owned by Nomad Foods. Analysis of variance revealed a highly significant variation between genotypes and genotype-by-environment interactions for the ten traits. The genetic diversity and population structure analyses estimated an intermediate level of genetic variation with two optimal sub-groups within the current panel. A total of 48 significant (P < 0.0001) MTAs were identified for eight different traits, including five for wrinkled vining pea yield on chr2LG1, chr4LG4, chr7LG7, and scaffolds (two), and six for adult plant resistance to downy mildew on chr1LG6, chr3LG5 (two), chr6LG2, and chr7LG7 (two). We reported several novel MTAs for different crucial traits with agronomic importance in wrinkled vining pea production for the first time, and these candidate markers could be easily validated and integrated into the active breeding programs for marker-assisted selection.
... Results from this study indicate that pod shattering in cowpea is more strongly associated with differences in the strength of pod wall fiber rather than the strength of the dehiscence zone (Fig. 3). This parallels variation found in certain other species, such as shattering resistance by To in common bean (Prakken, 1934) and P and V in pea (White, 1917;Blixt, 1978;Myers et al., 2001), which together eliminate wall fiber. The pattern contrasts with that of various other shattering resistance loci, such as SHAT1-SHAT5 of soybean (Dong et al., 2014), parallel mutations in several Lupinus spp. ...
Pod shattering, which causes the explosive release of the seeds from the pod, is one of the main sources of yield losses in cowpea in arid and semi-arid areas. Reduction of shattering has therefore been a primary target for selection during the domestication and improvement of cowpea, among other species. Using a mini-core diversity panel of 368 cowpea accessions, four regions with a statistically significant association with pod shattering were identified. Two genes (Vigun03g321100 and Vigun11g100600), involved in cell wall biosynthesis, were identified as strong candidates for pod shattering. Microscopical analysis was conducted on a subset of accessions representing the full spectrum of shattering phenotypes. This analysis indicated that the extent of wall fiber deposition was highly correlated with shattering. The results from this study also confirm that pod shattering in cowpea is exacerbated by arid environmental conditions. Finally, using a subset of West African landraces, patterns of historical selection for shattering resistance related to precipitation in the environment of origin were identified. Together, these results shed light on sources of resistance to pod shattering, which will, in turn, improve climate resilience of a major global nutritional staple.
... The P, V, and N genes of pea control the existence of pod wall fibers and eliminate pod shattering (White, 1917;Blixt, 1978;Myers et al., 2001). P and V each individually reduce endocarp fiber deposition, and together they eliminate all wall fiber deposition (Lamprecht, 1948). ...
A reduction in pod shattering is one of the main components of grain legume domestication. Despite this, many domesticated legumes suffer serious yield losses due to shattering, particularly under arid conditions. Mutations related to pod shattering modify the twisting force of pod walls or the structural strength of the dehiscence zone in pod sutures. At a molecular level, a growing body of evidence indicates that these changes are controlled by a relatively small number of key genes that have been selected in parallel across grain legume species, supporting partial molecular convergence. Legume homologues of Arabidopsis thaliana silique shattering genes play only minor roles in legume pod shattering. Most domesticated grain legume species contain multiple shattering-resistance genes, with mutants of each gene typically showing only partial shattering resistance. Hence, crosses between varieties with different genes lead to transgressive segregation of shattering alleles, producing plants with either enhanced shattering resistance or atavistic susceptibility to the trait. The frequency of these resistance pod-shattering alleles is often positively correlated with environmental aridity. The continued development of pod-shattering-related functional information will be vital for breeding crops that are suited to the increasingly arid conditions expected in the coming decades.
... Reduced pod parchment is a valuable agronomic trait that inhibits dehiscing of seed in mature crops and is one of the defining traits of the "Kaspa" plant type. Myers et al. (2010) indicated that this trait can be conferred by two complementary loci, the v locus on LG3 and the p locus on LG6. Our data suggest that Kaspa only contains the v locus as no QTL were observed on LG6 and χ 2 analysis clearly indicated a single gene was segregating in this population. ...
Trait-based selection to improve stress adaptation can complement direct selection for yield provided the trait meets six criteria: (1) it must be genetically correlated with yield in the target environments; (2) it should be less affected by the GxE interaction than yield; (3) it should not be associated with low yield in favourable conditions ; (4) it must show genetic variation; (5) it must be genetically stable, persistent across generations and relevant in different genetic backgrounds, and (6) it must lend itself to rapid, cost-effective and reliable quan-tification. Against these criteria, this study focused on pod wall ratio, defined as the weight ratio between the pod wall and the whole pod including seeds. We explored the phenotypic and genetic associations of this trait with yield components in a field pea population of 102 recombinant inbred lines (RILs) from a cross between Excel and Kaspa grown in two environments: Roseworthy 2015 (average yield 149 g m −2) and Turretfield 2016 (477 g m −2). All three sources of variation, environment, line and their interaction, affected yield (all P < 0.0001). The ranking of RILs for yield varied between environments, reflecting the strong G x E. The ranking of RILs for pod wall ratio was maintained between environments. Broad-sense heritability was higher for pod wall ratio (≥ 0.83) than for yield (≤ 0.59). There was a narrow range of pod wall ratio, 0.07 to 0.25 at Roseworthy 2015 compared to 0.09 to 0.52 in Turretfield 2016. Pod wall ratio correlated with seeds per pod and harvest index in Roseworthy 2015, and with yield, seeds per pod and harvest index in Turretfield 2016. A QTL for flowering time on linkage group 2 co-located with a QTL for a number of traits including pod wall ratio, days to pod emergence, seeds per pod, seeds per m 2 , shoot biomass at harvest and grain yield. These markers are potentially valuable for breeding after validation in independent populations.
... Snow and snap peas have probably been cultivated for centuries before any literature reference and are likely the result of spontaneous mutation of field and garden peas (Myers, 2001). Dr. Calvin Lamborn bred the snap pea that we are familiar with today in 1968 as a cross between the garden pea and snow pea (Janick, 2005). ...
Snow peas (Pisum sativum L. var. saccharatum) and snap peas (Pisum sativum L. var. macrocarpon) are high-value vegetables typically grown in temperate regions. The objective of this study is to evaluate if edible-pod peas can be grown in tropical climates like the U.S. Virgin Islands and to determine which variety obtains the highest yield under tropical conditions. Three cultivars of snow peas ['Oregon Giant' (OG), 'Mammoth Melting' (MM), 'Little Sweetie' (LS)], and three cultivars of snap peas ['Cascadia' (CA), 'Sugar Sprint' (SS), and 'Super Sugar Snap' (3S)] were grown at the University of the Virgin Islands, Agricultural Experiment Station, St. Croix, U.S. Virgin Islands. The experimental design was a complete randomized block consisting of six cultivar treatments with four replications. Prior to planting, trellises were constructed by stretching 1.5-m tall plastic mesh fencing between metal posts at 3 m intervals. Peas were seeded in double rows spaced at 7.6 cm in-row and 1 m between rows for a total of 263,157 plants ha-1. Peas were irrigated daily and fertigated weekly using an 8 L h-1 drip-tape. We applied a total of 67 kg ha-1 nitrogen using a commercial 20-20-20 soluble fertilizer. There was no difference in germination rate observed between cultivars (89% to 93%, P < 0.0001). Little Sweetie produced the highest total fruit yield for the season across all cultivars at 15,442 kg ha-1 (P < 0.0001) followed by OG and 3S at 10,775 and 9,760 kg ha-1 , respectively. All cultivars presented similar fruit sugar content (9 to 10° Brix). Of the varieties tested, LS is recommended for our conditions. Results of this experiment indicate that edible-pod peas have potential as a specialty, short-season, high-value crop when grown in the cooler months on St. Croix, USVI.
... Peas are usually divided into two types, field peas and vegetable peas. Field peas are also known as dry peas, while vegetable peas are referred to as garden or shell peas, Chinese or snow peas and snap peas (Myers et al. 2001). Snow peas and snap peas (edible-podded peas) are different from field peas and garden peas as the low fiber pods as well as the seeds are consumed. ...
With increasing consumer demand for vegetables, edible-podded peas have become more popular. Stringlessness is one of most important traits for snap peas. A single recessive gene, sin-2, controls this trait. Because pollen carrying the stringless gene is less competitive than pollen carrying the stringy gene, there are fewer than expected stringless plants recovered in segregating generations. Marker-assisted selection (MAS) is a valuable tool to identify plants with the traits of interest at an early stage in the breeding process. The objective of this study was to identify robust, user-friendly molecular markers tightly linked to sin-2. A total of 144 target region amplification polymorphism (TRAP) primer combinations were used to screen four DNA bulks, which were constructed from 32 pea breeding lines based on their phenotypes. Sixty polymorphic TRAP primer combinations were identified between bulks of stringless and stringy pods. Five primer combinations, F6_Trap03_168, F6_SA12_145, F10_ODD8_130, F11_GA5_850, and F12_SA12_190, showed more than 90 % association with the stringless phenotype in 32 pea breeding lines. Two of the TRAP markers, F10_ODD8_130 and F12_SA12_190, were cloned, sequenced, and successfully converted to sequence characterized amplified region (SCAR) markers. These two SCAR markers were validated using 20 F5 recombinant inbred lines derived from a cross between Bohatyr (a dry pea variety with strings) and S1188 (a stringless snap pea variety) and showed strong marker-trait association. The results will have direct application in MAS of stringless edible-podded peas.
... sativum var. macrocarpon; Myers et al., 2001). Garden peas are grown for their immature green seeds which can be used fresh or for canning and freezing. ...
In Wyoming USA, vegetable production is challenging for vegetable growers, whether home gardeners or commercial producers due to a short growing season, high elevation and a relatively cool climate. A significant limitation to local vegetable production is that virtually no vegetable varieties have been bred in Wyoming for local adaptation. As a cool season annual crop, pea has potential for vegetable production in Wyoming.
... The 'Snap Pea' cultivar originated from a cross of garden pea cultivar 'Dark Skin Perfection' with snow pea (Myers et al., 2001). The sweet, thick podded segregate was selected and called 'Sugar Snap'. ...
From early domestication to modern genetic approaches, the focus of the plant breeding has always been to serve the needs of the society. Historically, plant breeders have selected for agronomic traits such as higher yield and disease resistance. However, with the advent of extensive medical research implicating fruits, vegetables and their bioactive compounds in human health, it has become imperative to pursue enhancement of specific health promoting compounds. Determination of target traits and optimum levels of these compounds, however, need to be evaluated carefully after better understanding of their bioavailability in the food matrix. In addition, the role played by various disciplines of science as well as stakeholder input is important in determining the overall objectives of a breeding program. The current review discusses breeding efforts to increase certain health promoting compounds impacting human health, while maintaining quality and yield.
Molecular markers have great potential to improve the efficiency and precision of conventional plant breeding through marker-assisted selection (MAS). It is also important to identify outstanding parents, improve the selection of elite alleles at loci controlling important traits, and pyramid favorable alleles at multiple loci associated with a single trait or multiple traits. Currently, the efforts of marker-assisted breeding in vegetable breeding for horticultural crop improvement will benefit the targeted traits through new approaches like marker-assisted back crossing, genomic selection, etc. This will enhance efficiency, reduce costs, and save time in the ongoing breeding programme. Therefore, to achieve a substantial impact on vegetable crop improvement by MAS is a massive challenge for the scientists in the next few decades.KeywordsMolecular markersMASVegetable crops
Garden pea (Pisum sativum L.) is a well-recognized legume vegetable crop with a great history of classical genetic research. Its subtypes have distinct characteristics with the varied form of uses like raw green peas, frozen peas, fresh whole green pods in salad and canned whole green pods. Garden pea has three distinct botanical varieties viz., English pea or shell pea, Snow pea and Snap pea. English pea possessing parchment layer (sclerenchymatous membrane) on inner pod wall hence, shelling is required before use, whereas in snow and snap peas parchment layer on inner pod walls is absent therefore grouped as edible pod pea. Snow pea typically produces large and flat (constricted shape) pods and the snap pea bears round and thick-walled (inflated shape) pods which distinguish snap pea from snow pea. The edible-podded peas are unique to certain aspects of genetics, breeding, production and processing, but least information is available on these aspects of the edible-podded pea. This review discusses the origin, history, different types/subtypes with classification, physiological issues, genetics, improvement strategies and researchable facts of edible-podded peas.
The pea (Pisum sativum L.) is one of the most important crops in temperate agriculture around the world. In the tropics, highland production is also common with multiple harvests of nearly mature seeds from climbing plant types on trellises. While the leafless variant caused by the afila gene is widely used in developing row-cropped field peas in Europe, its use for trellised garden peas has not been reported. In this study we describe a pea breeding program for a high-elevation tropical environment in the Department of Nariño in Colombia, where over 16,000 hectares of the crop are produced. The most widespread climbing varieties in the region are 'Andina' and 'Sindamanoy', both of which have high-biomass architecture with abundant foliage. They are prone to many diseases, but preferred by farmers given their long production season. This plant type is expensive to trellis, with wooden posts and plastic strings used for vine staking constituting 52% of production costs. The afila trait could reduce these costs by creating interlocking plants as they do in field peas. Therefore, our goal for this research was to develop a rapid breeding method to introduce the recessive afila gene, which replaces leaves with tendrils, into the two commercial varieties used as recurrent parents (RPs) with three donor parents (DPs)-'Dove', 'ILS3575' and 'ILS3568'-and to measure the effect on plant height (PH) and yield potential. Our hypothesis was that the afila gene would not cause linkage drag while obtaining a leafless climbing pea variety. Backcrossing was conducted without selfing for two generations and plants were selected to recover recurrent parent characteristics. Chi-square tests showed a ratio of 15 normal leaved to one afila leaved in the BC2F2 plants, and 31:1 in the BC2F3 generation. Selecting in the last of these generations permitted a discovery of tall climbing plants that were similar to those preferred commercially, but with the stable leafless afila. The method saved two seasons compared to the traditional method of progeny testing before each backcross cycle; the peas reached the BC2F2 generation in five seasons and the BC3F2 in seven seasons. This is advantageous with trellised peas that normally require half a year to reach maturity. Leafless garden peas containing the afila gene were of the same height as recurrent parents and, by the third backcross, were equally productive, without the high biomass found in the traditional donor varieties. The value of the afila gene and the direct backcrossing scheme is discussed in terms of garden pea improvement and crop breeding.
Seed development largely depends on the long‐distance transport of sucrose from photosynthetically‐active source leaves to seed sinks. This source‐to‐sink carbon allocation occurs in the phloem and requires the loading of sucrose into the leaf phloem and, at the sink end, its import into the growing embryo. Both tasks are achieved through the function of SUT sucrose transporters. In this study, we used vegetable peas (Pisum sativum L.), harvested for human consumption as immature seeds, as our model crop and simultaneously overexpressed the endogenous SUT1 transporter in the leaf phloem and in cotyledon epidermis cells where import into the embryo occurs. Using this ‘Push‐and‐Pull’ approach, the transgenic SUT1 plants displayed increased sucrose phloem loading and carbon movement from source to sink causing higher sucrose levels in developing pea seeds. The enhanced sucrose partitioning further led to improved photosynthesis rates, increased leaf nitrogen assimilation, and enhanced source‐to‐sink transport of amino acids. Embryo loading with amino acids was also increased in SUT1‐overexpressors resulting in higher protein levels in immature seeds. Further, transgenic plants grown until desiccation produced more seed protein and starch, as well as higher seed yields than the wild‐type plants. Together, the results demonstrate that the SUT1‐overexpressing plants with enhanced sucrose allocation to sinks adjust leaf carbon and nitrogen metabolism, and amino acid partitioning in order to accommodate the increased assimilate demand of growing seeds. We further provide evidence that the combined Push‐and‐Pull approach for enhancing carbon transport is a successful strategy for improving seed yields and nutritional quality in legumes.
In Europe, agriculture is highly dependent on imported soybean from South America. Potential alternative sources are protein from peas (Pisum sativum L.) or more local sources like other grain legumes or rapeseed meal (Brassica napus L. subsp. oliefera). These are also good rotation crops. For farmers, protein and yield are key traits. In this study, a dataset containing 37 descriptors and 1222 accessions from a germplasm collection of P. sativum was analyzed. Scatterplot matrixes and tree regression analysis were used to establish the relationship among descriptors and to identify the most important predictors for seed yield and protein content respectively. Number of flowers per plant was shown to be important for seed yield prediction, followed by number of inflorescences per plant and number of pods per plant. In general, a negative correlation between seed protein content and seed yield was detected, but a few accessions that had both high seed yield and high protein content were identified. The results are discussed in relation to crop improvement and the importance of maintaining germplasm collections.
Current recommendations for maintaining quality of sugar snap peas in storage include low temperatures, but not modified atmospheres (MA). However, sugar snap peas may be unintentionally exposed to MA when shipped in 'bag in box' bulk packaging, or intentionally exposed when used as a component in fresh-cut vegetable trays. The aim of this research was to determine the tolerance of sugar peas to MA. Two experiments were conducted in which sugar snap peas ('Super Sugar Snap') were stored at 5°C for up to 21 days in air, 3% O2 + 7, 12 or 18% CO2, or 10% O2 + 12% CO2. Overall, storage in air resulted in the best quality based on subjective (overall visual quality, discoloration, aroma, decay) and objective measurements (sugar, ethanol, acetaldehyde, ammonia). The 3% O2 with 12 or 18% CO2 resulted in visible damage (discoloration) to the peas after 9 to 12 days. This was associated with changes in color (increased darkness, loss of greenness), and substantial increases in ammonia, ethanol and acetaldehyde; all indicative of stress. Quality changes in peas stored in 3% O2 + 7% CO2 or 10% O2 + 12% CO2 were intermediate between the stressful atmospheres and air. Further tests showed that peas ('Sugar Snap') maintained good quality at 5°C in air, 3% O2, 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres for 18 days. Best quality was maintained in air at 0°C for over 21 days. At 5°C for 18 days, some MA combinations provided slight benefit over air storage, and importantly did not result in increased concentrations of stress indicators. If peas have to be in MAP with other fresh-cut vegetables, the 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres are probably the better.
Fifteen pod characteristics were measured on parents and on F 1 and F 2 progeny of 14 crosses involving 9 cultivars or experimental lines of peas segregating for the n gene. In the F 2 generation, pods of nn plants were 17% shorter, 32% narrower, and 17% lighter in weight than normal ( N -) pods. Pod walls of nn plants were 54% thicker, primarily the result of an increase in the number of parenchyma cells, though cell size also tended to be greater. Variation among F 2 progeny indicated that plants with thicker and heavier pod walls can be developed.
Eight foliage types of pea ( Pisum sativum L.) were tested as near-isogenic lines of 8 cultivers and experimental lines for 2 years at 2 locations. Three blends of those foliage types were also tested at 1 location. Modifications of the pea foliage were determined by the action of the genes af (leaflets changed to tendrils), tl (tendrils changed to leaflets), and st (reduced stipule size). Shelled pea yields of the altered foliage types in pure stands were similar to normal except for the afaf TITI stst and afaf tltl stst types, which had reduced yields. The afaf TITl StSt and afaf TITI stst types had superior standing ability, and had less blonding of shelled peas. Yield was positively correlated with leaf area and harvest index. Blonding of shelled peas was positively correlated with leaf area. One of 2 foliage types with the most favorable performance for the 23 horticultural characteristics measured had many small leaflets ( afaf tltl StSt ), while the other had tendrils instead of leaflets ( afaf TITI StSt ). The all-tendril foliage type ( afaf TITI StSt ), either in pure stand or in a blend with another type, appears to have the most potential for replacing the normal foliage type.
TheNp mutant of pea (Pisum sativum L.) is characterized by two physiological responses: growth of callus under pea weevil (Bruchus pisorum L., Coleoptera: Bruchidae) oviposition on pods, and formation of neoplastic callus on pods of indoor-grown plants. Although these two responses are conditioned byNp, they are anatomically and physiologically distinguishable, based on sites of origin, distribution pattern, and sensitivity to plant hormones. Further characterization of the response to extracts of pea weevil showed that response of excised pods, measured by callus formation, was log-linear, and treatment with as little as 10−4 weevil equivalents produced a detectable response. Mated and unmated females contained similar amounts of callus-inducing compound(s), and immature females contained significantly less of the compound(s). Female vetch bruchids (Bruchus brachialis F., Coleoptera: Bruchidae), a related species, contained callus-inducing compound(s), but usually less than pea weevils on a per weevil basis. Males of both species contained less than 10% of the activity of the mature females. Extracts of female black vine weevils, a nonbruchid species, did not stimulate callus formation. Based on partitioning and TLC analysis, the biologically active constitutent(s) was stable and nonpolar. Thus, theNp allele probably conditions sensitivity to a nonpolar component of pea weevil oviposition as a mechanism of resistance to the weevil.
We have located an RFLP marker, corresponding to the locus Vc-5, which is linked to the r
b locus. We also show that the heterogeneity at the Vc-5 locus is less among r
brb lines than among pea genotypes as a whole. The relevance of this RFLP is discussed in relation to the construction of the double recessive rr r
brb genotypes.
Bruchid larvae cause major losses of grain legume crops through- out the world. Some bruchid species, such as the cowpea weevil and the azuki bean weevil, are pests that damage stored seeds. Others, such as the pea weevil (Bruchus pisorum), attack the crop growing in the field. We transferred the cDNA encoding the a-amylase inhibitor (a-AI) found in the seeds of the common bean (Phaseolus vulgaris) into pea (Pisum sativum) using Agrobacferium-mediated transformation. Expression was driven by the promoter of phytohe- magglutinin, another bean seed protein. The a-amylase inhibitor gene was stably expressed in the transgenic pea seeds at least to the T, seed generation, and a-AI accumulated in the seeds up to 3% of soluble protein. This level is somewhat higher than that normally found in beans, which contain 1 to 2% a-AI. In the 1, seed generation the development of pea weevil larvae was blocked at an early stage. Seed damage was minimal and seed yield was not significantly reduced in the transgenic plants. These results confirm the feasibility of protecting other grain legumes such as lentils, mungbean, groundnuts, and chickpeas against a variety of bruchids using the same approach. Although a-AI also inhibits human a-amy- lase, cooked peas should not have a negative impact on human energy metabolism.
Adult females of the coccinellid predator Hippodamia convergens (Say) spent more time walking and less time grooming on a line of peas, Pisum sativum L., that has reduced waxbloom on all parts of the plant (due to the mutation wel) compared with a near-isogenic sister line with normal waxbloom. H. convergens walking was distributed over all parts of the low-wax plants, whereas on normal-wax plants walking occurred mostly on stems and the edges of leaves and stipules. The beetles were able to generate 30 times the adhesive traction force on leaf surfaces of low-wax plants compared with normal-wax plants. In cage studies, H. convergens (4 adults per plant) were more effective at reducing population growth of pea aphid, Acyrthosiphon pisum (Harris), on low-wax plants than on normal-wax plants, but only at initial aphid densities of 10 aphids per plant. At higher initial densities (20 and 40 aphids per plant), differential impact of H. convergens was not observed or disappeared after 4-5 d. The results indicate that reduced waxbloom in peas could improve the effectiveness ofH. convergens on peas at low prey densities.
A linkage map of the pea (Pisum sativum L.) genome is presented which is based on F2 plants produced by crossing the marrowfat cultivar ‘Primo’ and the blue-pea breeding line ‘OSU442-15’. This linkage map consists
of 209 markers and covers 1330 cM (Kosambi units) and includes RFLP, RAPD and AFLP markers. By mapping a number of anchor
loci, the ‘Primo’בOSU442-15’ map has been related to other pea linkage maps. A feature of the map is the incorporation of
29 loci representing genes of known function, obtained from other laboratories. The map also contains RFLP loci detected using
sequence-characterized cDNA clones developed in our laboratory. The putative identities of 38 of these cDNA clones were assigned
by examining public-sequence databases for protein or nucleotide-sequence similarities. The conversion of sequence-characterized
pea cDNAs into PCR-amplifiable and polymorphic sequence-tagged sites (STSs) was investigated using 18 pairs of primers designed
for single-copy sequences. Eleven polymorphic STSs were developed.
Random amplified polymorphic DNA (RAPD) markers linked to two morphological markers ( fa and det), three ramosus genes (rms2, rms3 and rms4) and two genes conferring flowering response to photoperiod in pea (sn, dne) were selected by bulk segregant analysis on F2 populations. Two RAPD fragments were cloned and sequenced to generate the two SCAR markers V20 and S2 which are linked to
rms3 and dne, respectively. All these genes, except rms2, were previously located on the pea classical linkage map. Rms2 mapped to linkage group IB which contains the afila gene. Precise genetic maps of the regions containing the genes were obtained and compared to the RAPD map generated from
the recombinant inbred-lines population of the cross Térèse×K586. This cross was chosen because several mutants were obtained
from cultivars Térèse and Torsdag (K586 was derived from Torsdag). This collection of isogenic lines was used for the construction
of F2 mapping populations in which polymorphic RAPD markers were already known and mapped. Moreover, the well-known problem in
pea of variability in the linkage associations between crosses was avoided. This work contributes to the precise integration
between the classical map and the molecular maps existing in pea.
We have analyzed segregation patterns of markers among the late generation progeny of several crosses of pea. From the patterns of association of these markers we have deduced linkage orders. Salient features of these linkages are discussed, as is the relationship between the data presented here and previously published genetic and cytogenetic data.
Wild taxa are invaluable sources of resistance to diseases, insects/ pests, nematodes, temperature extremes, salinity and alkalinity stresses, and also of nutritional quality; adaptation; genetic diversity and new species. Utilization of wild relatives of a crop depends largely upon its crossability relations with cultivated varieties. Sev eral wild species are not crossable with the commercial cultivars due to various isolation barriers. Furthermore, in a few cases, hybridiza tion is possible only in one direction and reciprocal crosses are not successful, thus depriving the utilization of desired cytoplasm of many species. However, techniques have been developed to over come many barriers and hybrid plants are produced. New crop species have been developed by overcoming the F 1 sterility and producing amphidiploids and such crops are commercially being grown in the field. The segregation pattern ofF 1 hybrids produced by distant hybridization in segregating generations are different from the intervarietal hybrids. In former cases, generally, unidirectional segregation takes place in early generations and accordingly, selec tion procedures are adopted. In most of the cases, backcross or modified backcross methods have been followed to utilize wild species, and thus numerous types of resistance and other economical attributes have been transferred in the recurrent parents. Protoplast fusion has been amply demonstrated in a number of cases where sexual hybridization was not possible and, as a result, hybrids have been produced.
A reproducible transformation system was developed for pea (Pisum sativum L.) using as explants sections from the embryonic axis of immature seeds. A construct containing two chimeric genes, nopaline synthase-phosphinothricin acetyl transferase (bar) and cauliflower mosaic virus 35S-neomycin phosphotransferase (nptII), was introduced into two pea cultivars using Agrobacterium tumefaciens-mediated transformation procedures. Regeneration was via organogenesis, and transformed plants were selected on medium containing 15 mg/L of phosphinothricin. Transgenic peas were raised in the glasshouse to produce flowers and viable seeds. The bar and nptII genes were expressed in both the primary transgenic pea plants and in the next generation progeny, in which they showed a typical 3:1 Mendelian inheritance pattern. Transformation of regenerated plants was confirmed by assays for neomycin phosphotransferase and phosphinothricin acetyl transferase activity and by northern blot analyses. Transformed plants were resistant to the herbicide Basta when sprayed at rates used in field practice.
Why embark on another discussion of selection methods in common bean when currently used methods have the potential for substantial additional progress? For instance, the backcross and pedigree selection methods have led to high-yielding common bean cultivars resistant to Bean Common Mosaic Virus (BCMV) and to anthracnose (Colletotrichum lindemuthianum) (e.g., FOUILLOUX, 1976). Many snapbean cultivars with excellent pod quality and resistance to halo blight have been released in Europe and the USA. The largest common bean breeding program in the world — at the Centro Internacional de Agricultura Tropical in Cali, Colombia — is creating several hundreds of improved lines with multiple resistance to tropical diseases and pests using these conventional breeding methods. As a consequence, most of the factors which limited common bean production some 30 years ago (e.g., ZAUMEYER and THOMAS, 1957) are in the process of being eliminated.
In this chapter, we review the status of snap bean research and suggest directions for the future. The snap bean group is defined and differences with dry bean are delineated. The origin of edible podded bean, from their possible genesis in the New World, to expansion of genetic diversity in the Old World, to their reintroduction into the U.S.A. is considered. We examine world commercial production with particular emphasis on North American environments and production constraints. Genetic control for whole plant traits, pod traits, seed traits, and disease resistances of importance is discussed. Finally, we suggest areas in need of research and breeding objectives for the future.
In crosses between stringless and stringy podded pea cultivars, all plants of the F 1 and backcross to the stringy parent had stringy pods. F 2 ratios varied widely among crosses, and populations always had more stringy plants than expected, based on a single locus. The ratio of nonsegregating (stringy): segregating F 3 families derived from stringy F 2 plants fit a single-gene hypothesis in half of the crosses. Backcrosses of F 1 to the stringless parent fit the expected 1:1 ratio when the pollen parent was stringless, but the reciprocal backcrosses showed a deficiency of stringless plants, suggesting that poor competitive ability of pollen bearing the stringless factor was the reason for deficiencies of stringless plants. It is concluded that stringlessness is controlled by a single recessive gene for which the designation sin-2 is proposed. A reduction in pod size, plant height, and number of wrinkled seed segregates was associated with stringlessness.
Experimental evidence has shown that all forms of peas previously described as species have a diploid chromosome number of 14, that no sterility barriers exist, and that gene exchange is complete. The genus Pisum is therefore best regarded as monospecific in accordance with Lamprecht’s (1966) view. He classified the different forms as ecotypes included under Pisum arvense Linné, the wild-growing form of the two described by Linné. The ecotypes abyssinicum Braun; arvense (Linné) Lamprecht (including elatius Steven, jomardi Schrank, and transcaucasicum Stankov); fulvum Sibthorp and Smith; and humile Boissier (including syriacum/Berger/Lehmann) occur as wild-growing populations. All man-made genetic variations were collected together under the name sativum, the domesticated race. This system of classification is practical and workable, though perhaps not taxonomically orthodox. Pisum formosum Steven, which is a tuber-forming perennial, was separated to form the genus Alophotropsis (Boissier) Lamprecht.
Linkage between Adh-1 , the locus specifying the more anoda) isozyme of alcohol dehydrogenase, and En , the locus controlling resistance to pea enation mosaic virus, was investigated in the garden pea, Pisum sativum L. A recombination frequency of 4% was observed between the two loci, indicating that Adh-1 may be a practical marker for En . The use of Adh-1 in combination with other loci as brackets around En , thereby increasing the reliability of an indirect screen, is also discussed.
There was no difference in percentage in vitro germination of pollen from stringless pea (Pisum sativum L.) cv. Sugar Daddy and stringy `Oregon Sugarpod II' (OSP) and `OSU 705' (705). However, pollen tubes of `Sugar Daddy' grew more slowly in vitro than those of OSP or 705. Differences in pollen tube growth rate were demonstrated in vivo following time-course pollinations involving reciprocal crosses of `Sugar Daddy' with OSP and 705, along with the selfed parents. After 8 hours, pollen tubes from stringless peas (“stringless” pollen) had entered 13% of the ovules compared with 51% for those from stringy peas (“stringy” pollen). Stringless pollen tubes entered 29% and stringy pollen tubes 66% of the ovules after 10 hours. The slower growth of stringless compared with stringy pollen tubes is a plausible explanation for previously observed deficiencies of stringless plants in segregating populations.
The development of genetic engineering procedures for the introduction of foreign genes into peas has proved a difficult task. However, four years ago Puonti-Kaerlas (6) produced the first transgenic pea plants. Stable transformation was achieved by using resistance to the antibiotic hygromycin as the selectable marker. On further analysis it was found that all transgenic plants and progeny were aberrant types. Using kanamycin selection and B-glucuronidase as a reporter gene, Davies et al. (1) produced four transgenic pea lines. The method proved to be difficult to reproduce. Davies and Mullineaux (2) concluded that the system needed further development. We have reported the development of a routine reliable transformation and regeneration system for peas (9). This system was established using Agrobacterium-mediated gene transfer to introduce two chimeric genes, an antibiotic resistance gene (nptII) and a herbicide resistance gene (bar) into two cultivars of pea, Greenfeast and Rondo. The expression of the nptII and bar genes in primary transgenics and first generation progeny was confirmed by enzyme assays. It was found that the bar gene was an efficient selectable marker in the tissue culture phase of pea transformation. This gene confers resistance to phosphinothricin (PPT), the active ingredient in the non-selective herbicide Basta. The bar gene encodes the enzyme phosphinothricin acetyl transferase (PAT) which catalyses the conversion of PPT to a non-toxic acetylated product (Fig. 1). The bar gene is also a screenable marker with great potential for use in conventional breeding when foreign genes from transgenic plants are transferred to existing commercial cultivars. Either painting of individual leaves or spraying of plants with the herbicide will indicate expression of the bar gene (9) and because of linkage to the other genes in the introduced construct, will serve as a scoreable phenotypic marker. Although gene transfer into peas in our laboratory was established using the garden pea cultivars Greenfeast and Rondo, the procedures have now been extended to the transfer of useful genes into Australian field pea cultivars Dundale and Laura. As a result of discussions with pea breeders, pea growers, and pea marketers, the initial aims of our pea crop improvement program are to introduce three new traits, namely, resistance to the insect pest, pea weevil (Bruchus pisorum), tolerance to the herbicide Basta, and improved nutritional quality of pea seed proteins. Bean α α α α-amylase inhibitor confers resistance to Bruchid weevils attacking stored grain The fully matured, stored seeds of peas and other grain legumes such as chickpeas, cowpeas and Azuki beans are susceptible to infestation by seed-feeding bruchids (Callosobruchus sp.). The seeds of another grain legume, the common bean (Phaseolus vulgaris), are resistant to these seedfeeding bruchids because of the presence of a seed protein with high insecticidal activity, the α-amylase inhibitor protein (αAI). Studies with artificial diets (3, 4) showed that the development of two seed-feeding beetles, the cowpea weevil (Callosobruchus maculatus) and the Azuki bean weevil (C. chinensis), was inhibited by relatively low levels of bean αAI in the diet. This information prompted us to investigate whether transfer and expression of the bean αai gene in peas might confer protection against these pests of stored grain legumes.
A transformation system that allows regeneration of transgenic pea plants from calli selected for antibiotic resistance was developed. Explants from axenic shoot cultures and seedling epicotyls were cocultivated with nononcogenic Agrobacterium tumefaciens strains, and transformed callus could be selected on callus-inducing media containing either 15 mg/l hygromycin or 75 mg/l kanamycin. After several passages on regeneration medium, shoot organogenesis could be reproducibly induced on hygromycin-resistant calli, but not on the calli selected for kanamycin resistance. Regenerated shoots could subsequently be rooted and transferred into the greenhouse. In addition, the effects of different callus-inducing and growth media on organogenesis were investigated. The transformation of the calli and regenerated plants was confirmed by DNA analysis.
The lateral cotyledonary meristems present in germinating seed were inoculated with a non-oncogenic strain of A. tumefaciens carrying a gene conferring kanamycin resistance as a selectable marker and a β-glucuronidase sequence as a reporter gene. Kanamycin resistant plants were derived from the meristems and shown to be transformed on the basis of Southern blots, polymerase chain reaction analysis and tests for β-glucuronidase activity. The plants were fertile and tests of their progeny confirmed the transmission of integrated sequences through a sexual generation. This transformation method has the merit of an unlimited supply of material for inoculation and a relatively short time scale from inoculation to the production of rooted plants.
The location of sbm-1 on the Pisum sativum genetic map was determined by linkage analysis with eight syntenic molecular markers. Analysis of the progeny of two crosses confirmed that sbm-1 is on chromosome 6 and permitted a more detailed map of this chromosome to be constructed. The inclusion of Fed-1 and Prx-3 among the markers facilitated the comparison of our map with the classical genetic map of pea. The sbm-1 gene is most closely linked to RFLP marker GS185, being separated by a distance of about 8 cM. To determine the practical value of GS185 as a marker for sbm-1 in plant breeding programs, the GS185 hybridization pattern and virus-resistance phenotype were compared in of a collection of breeding lines and cultivars. Three GS185 hybridization patterns were discerned among the lines. A strong association was found between one of these patterns and resistance to PSbMV.
Linkage analysis was used to determine the genetic map location of er-1, a recessive gene conditioning resistance to powdery mildew, on the Pisum sativum genome. Genetic linkage was demonstrated between er-1 and linkage group 6 markers after analyzing the progeny of two crosses, an F2 population and a set of recombinant inbred lines. The classes of genetic markers surrounding er-1 include RFLP, RAPD and allozyme markers as well as the morphological marker Gty. A RAPD marker tightly linked to er-1 was identified by bulked segregant analysis. After DNA sequence characterization, specific PCR primers were designed to convert this RAPD marker into a sequence characterized amplified region (SCAR).
A reliable Agrobacterium tumefaciens-mediated transformation method has been developed for peas (Pisum sativum) using immature cotyledons as the explant source. Transgenic plants were recovered from the four cultivars tested: Bolero, Trounce, Bohatyr and Huka. The method takes approximately 7 months from explant to seed-bearing primary regenerant. The binary vector used carried genes for kanamycin and phosphinothricin resistance. Transformed pea plants were selected on 10 mg/l phosphinothricin. The nptII and bar genes were shown to be stably inherited through the first sexual generation of transformed plants. Expression of the phosphinothricin-resistance gene in the transformed plants was demonstrated using the 'Buster' (='Basta') leaf-paint test and the phosphinothricin acetyl transferase enzyme assay.
An F2 population of pea (Pisum sativum L.) consisting of 174 plants was analysed by restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) techniques. Ascochyta pisi race C resistance, plant height, flowering earliness and number of nodes were measured in order to map the genes responsible for their variation. We have constructed a partial linkage map including 3 morphological character genes, 4 disease resistance genes, 56 RFLP loci, 4 microsatellite loci and 2 RAPD loci. Molecular markers linked to each resistance gene were found: Fusarium wilt (6 cM from Fw), powdery mildew (11 cM from er) and pea common Mosaic virus (15 cM from mo). QTLs (quantitative traits loci) for Ascochyta pisi race C resistance were mapped, with most of the variation explained by only three chromosomal regions. The QTL with the largest effect, on chromosome 4, was also mapped using a qualitative, Mendelian approach. Another QTL displayed a transgressive segregation, i.e. the parental line that was susceptible to Ascochyta blight had a resistance allele at this QTL. Analysis of correlations between developmental traits in terms of QTL effects and positions suggested a common genetic control of the number of nodes and earliness, and a loose relationship between these traits and height.
Quantitative trait loci (QTLs) affecting seed weight in pea (Pisum sativum L.) were mapped using two populations, a field-grown F2 progeny of a cross between two cultivated types ('Primo' and 'OSU442-15') and glasshouse-grown single-seed-descent recombinant inbred lines (RILs) from a wide cross between a P. sativum ssp. sativum line ('Slow') and a P. sativum ssp. humile accession ('JI1794'). Linkage maps for these crosses consisted of 199 and 235 markers, respectively. QTLs for seed weight in the 'Primo' x 'OSU442-15' cross were identified by interval mapping, bulked segregant analysis, and selective genotyping. Four QTLs were identified in this cross, demonstrating linkage to four intervals on three linkage groups. QTLs for seed weight in the 'JI1794' x 'Slow' cross were identified by single-marker analyses. Linkage were demonstrated to four intervals on three linkage groups plus three unlinked loci. In the two crosses, only one common genomic region was identified as containing seed-weight QTLs. Seed-weight QTLs mapped to the same region of linkage group III in both crosses. Conserved linkage relationships were demonstrated for pea, mungbean (Vigna radiata L.), and cowpea (V. unguiculata L.) genomic regions containing seed-weight QTLs by mapping RFLP loci from the Vigna maps in the 'Primo' x 'OSU442-15' and 'JI1794' x 'Slow' crosses.
The benefits of a mutant-based approach to the examination of elongation growth are Outlined. In Pisum sativum L. 15 mutants have been isolated that modify elongation and multiple alleles have been identified at nine of these loci. Using appropriate screening techniques these mutants have been shown to modify growth in a wide range of ways. Four mutants, le, na, lh, and ls, block the synthesis of GA1 while s/n increases GA1 levels by blocking GA-catabolism. Two mutants, lv and lw, are classified as photomorphogenic mutants. While lv lacks responses attributable to phytochrome B, lw displays an enhanced response to phytochrome. Several mutants lacking a normal response to GA1 have been identified and include lk, lka, lkb, lkc, lkd, and la cry(s). The mutations lka and lkb alter the chemorheological properties of the cell wall and result in increases in the wall-yield threshold and turgor pressure while la and cry(s) may act at, or close to, the point of reception of the GA1 signal. The role of auxin in elongation of intact plants is currently being examined using these mutants since some modify IAA levels (e.g., lkb, lv). Other growth processes are also influenced by many of these mutants. Leaf growth is examined as an example of how mutants of known effect (e.g., dwarf, GA biosynthesis mutants) may be used to determine the role of hormones in other related developmental processes.
Recent advances in grain legume biotechnology are reviewed. Emphasis is given on field testing and commercialization of transgenic grain legumes. The absence of variety-independent gene transfer methods for major agronomic species has, until now, limited the usefulness of recombinant DNA techniques to crop improvement programs. Direct DNA transfer techniques into organized and easily regenerable tissue provided the breakthrough to achieve effective and practical gene transfer into important leguminous species. In principle, we are now in the position to introduce any foreign gene into almost all major legumes, in some cases in a variety-independent fashion. This, however, can only be achieved routinely in few laboratories, all located in industrialized countries. A number of the more important of the leguminous crops, particularly those utilized for human consumption are important components of sustainable agricultural production systems in the developing world. We must bridge the gap between industrialized and developing countries before legume biotechnolgy can be utilized effectively for crop improvement, particularly in the developing world. Technology transfer becomes an important issue and links amongst corporate research organizations, academic institutions and international organizations need to be strengthened to avoid duplication of effort and to maximize efficient utilization of limited resources. In this chapter, advantages of the various gene delivery methods that were shown to be useful for specific crops, as well as limitations and problems associated with each crop and gene transfer method will be discussed. In addition, we will focus on specific biotechnology goals targeted for particular crops. Important oilseed and feed species as well as minor but equally important species for sustaining growing populations in developing countries are discussed.
Powdery mildew is a serious disease of pea caused by the obligate parasite Erysiphe pisi Syd. Random amplified polymorphic DNA (RAPD) analysis has emerged as a cost-effective and efficient marker system. The objective of this study was to identify RAPD markers for powdery mildew resistance gene er-1. The resistant cultivar Highlight (carrying er-1) and the susceptible cultivar Radley were crossed, and F3 plants were screened with Operon (OP) and University of British Columbia (UBC) primers, using bulked segregant analysis. A total of 416 primers were screened, of which amplicons of three Operon primers, OPO-18, OPE-16, and OPL-6, were found to be linked to er-1. OPO-181200 was linked in coupling (trans to er-1) and no recombinants were found. OPE-161600 (4 ± 2 cM) and OPL-61900 (2 ± 2 cM) were linked in repulsion (cis to er-1). The fragments OPO-181200 and OPE-161600 were sequenced and specific primers designed. The specific primer pair Sc-OPO-181200 will be useful in identifying homozygous resistant individuals in F2 and subsequent segregating generations. Sc-OPE-161600 will have greatest utility in selecting heterozygous BC\dn6 nF1 individuals in backcross breeding programs.Key words: bulked segregant analysis,Erysiphe pisi, pea, RAPD.
The lateral cotyledonary meristems of germinatingPisum sativum cv. Puget seeds were used to develop a reproducibleAgrobacterium tumefaciens-mediated transformation system. This procedure exhibits distinct advantages over those previously reported, in that it uses dry seed as starting material, and the highly regenerable cotyledonary meristems rapidly produce transgenic shoots without an intermediate callus phase. This transformation regime facilitates the rapid generation of phenotypically normal, self-fertile plants containing functional transgenes inherited in a Mendelian fashion.
A genetic linkage map of Pisum sativum L. was constructed based primarily on RAPD markers that were carefully selected for their reproducibility and scored in a
population of 139 recombinant inbred lines (RILs). The mapping population was derived from a cross between a protein-rich
dry-seed cultivar ‘Térèse’ and an increased branching mutant (K586) obtained from the pea cultivar ‘Torsdag’. The map currently
comprises nine linkage groups with two groups comprising only 6 markers (n=7 in pea) and covers 1139 cM. This RAPD-based map has been aligned with the map based on the (JI281×JI399) RILs population
that currently includes 355 markers in seven linkage groups covering 1881 cM. The difference in map lengths is discussed.
For this alignment 7 RFLPs, 23 RAPD markers, the morphological marker le and the PCR marker corresponding to the gene Uni were used as common markers and scored in both populations.