[Show abstract][Hide abstract] ABSTRACT: Erianthus is a wild relative of the genus Saccharum. It is well known for its high fibre, high biomass, tolerance to drought and water logging, pest and disease resistance with multi-ratooning ability. This study was conducted to investigate physiological and molecular responses of Erianthus spp. to drought stress. Out of seven Erianthus accessions screened, the drought responsiveness of the broad-leaved accession of Erianthus arundinaceus IK 76-81 was found the best and characterised by high cell membrane thermostability, stomatal conductance, transpiration rate and relative water content and low photosynthetic rate under increased soil moisture stress. In addition, IK 76-81 also showed many fold increase in DREB2 and expansin gene expression with increase in soil moisture stress in comparison with the most popular moderately drought tolerant variety Co 86032. We have also evaluated few selected sugarcane × Erianthus hybrids and assessed the introgression of one of the key drought responsive characters i.e., cell membrane stability from Erianthus to sugarcane. This is perhaps the first report on the drought responsiveness of Erianthus.
[Show abstract][Hide abstract] ABSTRACT: The understanding on the available genetic variability in the breeding pool aids the breeder to choose better parental combinations for the desired genetic improvement in crop plants. The variability present in the National Hybridisation Garden (NHG) of sugarcane in India at Sugarcane Breeding Institute, Coimbatore with an assemblage of 606 clones of sugarcane cultivars and other elite hybrids were studied for cane yield components, juice quality parameters and their level of resistance against red rot. The data on smut resistance, tolerance to stalk borer and tolerance to different abiotic stresses like drought, salinity, water logging, low temperature, high temperature and winter ratooning ability of these clones to be used parental clones were collected from the available literature. Significant leptokurtic distribution for the cane characters and right skewed distribution for juice quality traits were observed in this breeding pool. Correlation studies indicated that selection of parents contributing to high cane height and high number of millable canes (NMC) would result in progeny with high single cane weight (SCW) and cane yield because, the SCW was negatively correlated with NMC and cane thickness. Clones with high per se performance for important yield contributing characters were identified which are potential parents for yield improvement. For sucrose content, a highly heritable trait in sugarcane, nineteen clones with high juice sucrose of more than 20 % were found to be suitable as parents for quality enhancement. One hundred and thirty-seven clones were found as either resistant (R) or moderately Rto the most virulent races of red rot pathogen by testing with mixed inoculum of Cf 671 and Cf 94012 isolates. Screening of the clones for pollen fertility inferred that NHG has higher number of clones that can be used as female parent than as male parent. The synchrony in flowering of female and male parental clones with desirable traits of interest and the combining ability of the clones are also discussed in this paper. The critical consideration of the different parameters in choosing suitable parental clones in crossing programme will help in rapid varietal improvement for cane and sugar yield as well as to enhance the resistance against different biotic and abiotic stresses for increased sugarcane productivity.
[Show abstract][Hide abstract] ABSTRACT: The first phase of transgenic research in sugarcane concentrated on the development and evaluation of transgenic lines transformed
for resistance to biotic stresses, particularly diseases and insect pests. Sugarcane is attacked by a range of insects including
tissue borers, sucking pests and canegrubs. Losses due to these pests are estimated to be around 10%. Although chemical control
and integrated pest management are regularly practiced for the control of insect pests, success is often limited due to practical
difficulties. The genetic complexity of sugarcane coupled with the non-availability of resistance genes in the germplasm has
made conventional breeding for insect resistance difficult. In this context, transgenic technology has become a handy tool
for imparting insect resistance to an elite variety which is otherwise superior for most other agronomic traits. A number
of transgenic sugarcane lines have been developed with genes expressing Cry proteins, proteinase inhibitors or lectins resistant
to borers, sucking insects or grubs. While commercializing transgenic lines, issues such as higher and stable transgene expression,
preparedness for resistance management and non-target effects need to be addressed. To manage the constant threat of resistance
development in target insects, it is imperative to deploy field-level strategies taking clues from other crops coupled with
the search for new potent replacement molecules for transformation.
Bt toxins–Proteinase inhibitors–GNA–Insect resistance–Non-target effects
[Show abstract][Hide abstract] ABSTRACT: We evaluated the insecticidal toxicity of Cry1Aa, Cry1Ab and Cry1Ac toxins against neonate larvae of sugarcane shoot borer Chilo infuscatellus Snellen (Lepidoptera: Crambidae) in vitro on diet surface. With the lowest LC(50) value, Cry1Ab emerged as the most effective among the three toxins. Sugarcane cultivars Co 86032 and CoJ 64 were transformed with cry1Ab gene driven by maize ubiquitin promoter through particle bombardment and Agrobacterium-mediated transformation systems. Gene pyramiding was also attempted by retransforming sugarcane plants carrying bovine pancreatic trypsin inhibitor (aprotinin) gene, with cry1Ab. Southern analysis confirmed multiple integration of the transgene in case of particle bombardment and single site integration in Agrobacterium-mediated transformants. The expression of cry1Ab was demonstrated through Western analysis and the toxin was quantified using ELISA. The amount of Cry1Ab protein in different events varied from 0.007 to 1.73% of the total soluble leaf protein; the events transformed by Agrobacterium method showed significantly higher values. In in vivo bioassay with neonate larvae of shoot borer, transgenics produced considerably lower percentage of deadhearts despite suffering feeding damage by the borer compared with the untransformed control plants. Expressed Cry1Ab content was negatively related to deadheart damage. Aprotinin-expressing sugarcane pyramided with cry1Ab also showed reduction in damage. The potential of producing sugarcane transgenics with cry1Ab and aprotinin genes resistant to early shoot borer was discussed in the light of the results obtained.
[Show abstract][Hide abstract] ABSTRACT: Sugarcane being clonally propagated, its transgenics with the desired trait in a commercial variety need not undergo sexual cycle as that in seed propagated crops in varietal selection or maintenance breeding and in cultivation. Even then, the successful transmission of transgene to the progeny is important in breeding programmes involving transgenics for further improvement by hybridization and clonal selection. Sixty two plants in the progeny of the cross between a transgenic line CoJ 64-3 carrying the cry1Ab gene and an untransformed commercial variety Co 775 were tested by PCR analysis and 31 plants were found to have the transgene. The quantification of Cry protein in leaf samples was done by ELISA. The Cry protein in the total soluble leaf protein in the progeny varied from 0.15 % to 1.19 %, where as in parent it was 0.13 %. In the selfed progeny of three transgenics events of Co 86032 with aprotinin gene the transgene transmission was found to be 32 %, 34 % and 50 %, less than the frequency expected by Mendelian segregation.
[Show abstract][Hide abstract] ABSTRACT: An unusual stalk rot was noticed in sugarcane varieties at the Sugarcane Breeding Institute, Coimbatore, and in clones of
sugarcane germplasm at the Sugarcane Breeding Institute Research Centre, Kannur, at maturity stage of the crop. Affected cane
stalks showed straw coloured rind discolouration. Internally, orange-brown rotting was noticed at nodal regions, which extended
further to internodal region emitting a distinctive sour odour. In some cases brownish discolouration throughout the infected
canes was noticed. In severe cases, rotting of entire stalks and desiccation were observed. Blackish discolouration of the
dried canes revealed numerous coiled thread like spore masses extruding from black pustules that break through the rind of
the entire cane stalk. A survey for the intensity of the disease revealed that collections ofSaccharum spp. as well as hybrid clones were affected to the tune of trace to cent per cent infection. The pathogen cultured from the
infected canes was identified asPhaeocytostroma sacchari (Ellis and Everh.) Sutton. Association of other fungi such asFusarium moniliformae,Varonaea botryosa andColletotrichum gloeosporioides was also found in certain infected samples. This is the first report of stalk rot disease caused byP. sacchari in India.
[Show abstract][Hide abstract] ABSTRACT: An unusual stalk rot was noticed in sugarcane varieties at the Sugarcane Breeding
Institute, Coimbatore, and in clones of sugarcane germplasm at the Sugarcane Breeding
Institute Research Centre, Kannur, at maturity stage of the crop. Affected cane stalks
showed straw coloured rind discolouration. Internally, orange-brown rotting was
noticed at nodal regions, which extended further to internodal region emitting a
distinctive sour odour. In some cases brownish discolouration throughout the infected
canes was noticed. In severe cases, rotting of entire stalks and desiccation were
observed. Blackish discolouration of the dried canes revealed numerous coiled thread
like spore masses extruding from black pustules that break through the rind of the entire
cane stalk. A survey for the intensity of the disease revealed that collections of
Saccharum spp. as well as hybrid clones were affected to the tune of trace to cent per
cent infection. The pathogen cultured from the infected canes was identified as
Phaeocytostroma sacchari (Ellis and Everh.) Sutton. Association of other fungi such
asFusarium moniliformae, Varonaea botryosa and Colletotrichum gloeosporioides was
also found in certain infected samples. This is the first report of stalk rot disease caused
by P. sacchari in India.
[Show abstract][Hide abstract] ABSTRACT: The Sugarcane Breeding Institute at Coimbatore maintains the world collection of
sugarcane germplasm at its research centre at Cannanore in Kerala, India. The germplasm has been maintained in the field by clonal replanting every year, in a
relatively pest- and disease- free condition, for more than 3 decades. However, the
presence of a new virus, sugarcane bacilliform badna virus (SCBV), which has been
reported from most other sugarcane growing countries, was recently detected in some
clones in Kerala. The foliar symptoms presumed to be those of SCBV varied in
different clones, but the most pronounced were freckles, chlorotic stripes of varying
length, narrowing of leaves and stunted growth. These symptoms were seen on many
clones of Saccharum officinarum, S. barberi, S. sinense, S. robustum, and a few hybrids
such as CP 44-101. Among the different species, the noble canes, S. officinarum, are
most prone to this virus and clones of the species collected before 1970 were heavily
infected compared with more recent additions. Almost all the clones of S. barberi and S.
sinense were infected. Among the wild species of sugarcane (S. spontaneum and S.
robustum) only a limited number of clones had suspected infection. Most of the hybrid
clones housed here have not exhibited symptoms of the virus except the clones D 1135,
D 1135 str., D 109 and CP 44-101, of which the first 3 are intraspecific hybrids of S.
officinarum. Techniques such as ELISA and immune electron microscopy (IEM) were
standardised for the detection of the virus in suspected clones. Occurrence of the virus
in sugarcane germplasm in India and other countries is a serious hindrance to exchange
of sugarcane germplasm. The precision of virus indexing in the suspected clones is to be
enhanced by detecting the virus through DNA probes and polymerase chain reaction
(PCR) analysis. It is concluded that the development of strategies to eliminate the virus
from infected clones needs immediate attention.