ABSTRACT
Diploid cotton, due to its inherent problem of stamen brittleness, its found unsuitable for traditional method of hybrid seed production which involves hand emasculation followed by pollination. Due to shortfall in other methods viz., Genetic Male Sterility (GMS), as well as, Cytoplasmic Genetic Male Sterility (CGMS), hybrid seed production in diploid cotton becomes costly and thereby, covers less area among the total cotton grown area. Thermo-sensitive genetic male sterility, which overcomes the drawbacks of both GMS and CGMS can be an effective tool in coming years for hybrid cotton research. Understanding fertility and sterility variations, their relation with biochemical changes in plant is important before its application in plant breeding. Hence, the available TGMS line, Ga TGMS-3 obtained at Cotton Research Centre, UAS, Dharwad was studied for callase activity and markers associated with TGMS. The line Ga TGMS-3 had fertile anthers and showed less callase enzyme activity at pre-meiosis stage, high enzyme activity at tetrad releasing microspore stage and no callase activity during other stages. The counterpart TGMS sterile anthers displayed little higher callase activity at pre-meiosis stage, high activity at tetrad stage, but poor activity at tetrad releasing microspore stage. During tetrad stage, TGMS sterile anthers showed high callase enzyme activity giving every chance for early release of poorly developed microspores as compared to fertile anthers. At tetrad releasing microspores stage during which fertile anthers had strong callase enzyme activity led to microspores being released normally and developed normal pollen grains as compared to sterile anthers. The present investigation revealed that NAU2176, NAU2096 and BNL1227 primers can be used as tightly linked markers for TGMS trait, as evident from their differential expression in fertile and sterile anthers.
Subject(s)
Diploidy , Expressed Sequence Tags , Gossypium/physiology , Fertility , Gossypium/genetics , Hot Temperature , Microsatellite Repeats , ReproductionABSTRACT
A comprehensive study was conducted using PPSMV resistant (BSMR 736) and susceptible (ICP 8863) genotypes to develop a segregating population and understand the inheritance of PPSMV resistance. The observed segregation was comparable to 13 (susceptible): 3 (resistant). Hence, the inheritance was controlled by two genes, SV1 and SV2, with inhibitory gene interaction.
ABSTRACT
Root system is a vital part of plants for absorbing soil moisture and nutrients and it influences the drought tolerance. Identification of the genomic regions harbouring quantitative trait loci (QTLs) for root and yield traits, and the linked markers can facilitate sorghum improvement through marker-assisted selection (MAS) besides the deeper understanding of the plant response to drought stress. A population of 184 recombinant inbred lines (RILs), derived from E36-1 × SPV570, along with parents were phenotyped for component traits of yield in field and root traits in an above ground rhizotron. High estimates of heritability and genetic advance for all the root traits and for most of the yield traits, presents high scope for improvement of these traits by simple selection. A linkage map constructed with 104 marker loci comprising 50 EST-SSRs, 34 non-genic nuclear SSRs and 20 SNPs, and QTL analysis was performed using composite interval mapping (CIM) approach. A total of eight and 20 QTLs were mapped for root and yield related traits respectively. The QTLs for root volume, root fresh weight and root dry weight were found co-localized on SBI-04, supported by a positive correlation among these traits. Hence, these traits can be improved using the same linked markers. The lack of overlap between the QTLs of component traits of root and yield suggested that these two sets of parameters are independent in their influence and the possibility of combining these two traits might enhance productivity of sorghum under receding moisture condition.
ABSTRACT
A survey was conducted in 47 locations in nine cotton-growing states of India to identify the composition of mealybug species occurring on cotton. Results of the taxonomic study showed that two mealybug species, the solenopsis mealybug, Phenacoccus solenopsis (Tinsley), and the pink hibiscus mealybug, Maconellicoccus hirsutus (Green), were found to infest cotton plants from all nine cotton growing states of the country. However, P. solenopsis was found to be the predominant mealybug species, comprising 95% of the samples examined. P. solenopsis, which was hitherto not reported to occur in India, now appears to be widespread on cotton in almost all cotton-growing states of the country. P. solenopsis is an exotic species originated from the USA and was reported to damage cotton and crops of 14 families. This report discusses the implications of the introduction of this exotic polyphagous pest species and the necessary steps to mitigate its potential threat to agriculture in India.
