ICRISAT,Patancheru 502 324,Andhra Pradesh,IndiaMini-biographyDr Rajeev Varshney has over 10 years research experience in the area of plant genomics and crop biotechnology. After earning the Ph.D. degree from India, he worked at Institute of Plant Genetics and Crop Plant Research (IPK), Germany for about five years and he joined the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), India in 2005. He has over 60 research papers/articles in the reputed journals (e.g. PNAS, USA, Trends in Plant Sciences, Trends in Biotechnology, The Plant Journal, Theor. Appl. Genet., Plant Breeding, Euphytica, etc.) and two edited books (Cereal Genomics- Kluwer and Model Plants and Crop Improvement- CRC Press) to his credit. The citation index of his published papers has already exceeded the 500 numbers. He has participated, as invited speaker, chairman, facilitator and rapporteur, in several international workshops/symposia/conferences/meetings. He is serving some journals e.g. Euphytica and Plant Genetic Resources as Associate Editors and the international ‘Triticeae EST-SSR Coordination’ platform and the ‘Recombinational Analysis’ coordination area of the International Triticeae Mapping Initiative (ITMI) as Coordinator.
He has interest in development and application of genomic tools and strategies for applied breeding of the legume and cereal crops of the semi-arid tropics.
About the GL-TTP, Dr Varshney says
"The GL-TTP provides an excellent network among legume genomics researchers and breeders and will be playing a central role in transferring the upstream legume genomics research to downstream applications in legume breeding.”
Genomics-assisted breeding for legume improvement: prospects and constraintsRajeev K. Varshney
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Patancheru- 502 324, Andhra Pradesh, India
r.k.varshney@cgiar.orgIn recent years, a truly impressive number of advances in genetics and genomics have greatly enhanced our understanding of structural and functional aspects of plant genomes but at the same time have challenged us with many compelling avenues of investigation. The complete genome sequences of Arabidopsis, rice and poplar as well as an enormous number of crop plant ESTs have become available. In the next several years, the entire genomes or at least gene space will likely be sequenced for some model crop species like Medicago, Lotus, and major crop species like sorghum, tomato and soybean. However, improved varieties, not sequences per se, contribute to improved economic return to the farmer. Functional genomics research is facilitating the identification of gene networks that are involved in the relationships between DNA sequence and trait phenotypes in elite breeding populations. Furthermore, combining the new knowledge from genomics research with traditional breeding methods is essential for enhancing crop improvement. Superior varieties can result from the discovery of novel genetic variation, improved selection techniques, or the identification of genotypes with new or improved attributes due to superior combinations of alleles at multiple loci. Advances in genomics can contribute to crop improvement in two general ways: first a better understanding of the biological mechanisms can lead to new or improved screening methods for selecting superior genotypes more efficiently and second, new knowledge can improve the decision-making process for more efficient breeding strategies. Although it is clear that the genomics research has great potential to revolutionize the discipline of plant breeding, high costs invested in/associated with genomics research in food legume crops currently limit the implementation of genomics-assisted crop improvement, especially for inbreeding and/or crops of minor importance. The prospects, achievements as well as constraints of the applications of genomics in breeding for food legume improvement will be discussed in the presentation.
Genomics and physiological approaches for enhancing molecular breeding strategies for drought tolerance in chickpea (Cicer arietinum L.)Rajeev Varshney
1, Dave Hoisington
1, Junichi Kashiwagi
1, Pooran Gaur
1, Hari Upadhyaya
1, Subhash Chandra
1, Spurthi Nayak
1, Jayashree Balaji
1, Dominique This
2, Peter Winter
31International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, India
2 Montpellier SupAgro, Agropolis, Montpellier cedex, France
3University of Frankfurt, D-60439 Frankfurt am Main, Germany
r.k.varshney@cgiar.orgTerminal drought is the number one constraint to chickpea production in over 70% of chickpea cultivating area. We have shown that a prolific and deep root system can confer better growth and yield under terminal drought. Using a tall PVC cylinder technique (120-cm height) to evaluate germplasm for root traits under terminal drought conditions, a number of avoidance traits including root biomass, root length density and root depth have been identified. In field trials, a good correlation was found between the rooting profile and the seed yield and harvest index. The root length density in 15-30cm in depth had positive effects to the seed yield and harvest index irrespective of the terminal drought intensity, and the deep rooting showed the same effects especially under conditions of severe drought, which suggests the potential of deep rooting to help achieving a better seed setting and better seed filling under severe water deficit that may contribute to stabilize yield across erratic water scenarios.
To enhance molecular breeding strategies for drought tolerance, two genomics approaches are being used at ICRISAT in collaboration with our partners. In the first approach, molecular mapping of root traits using microsatellite or SSR markers has been initiated. Initial genotyping of a mapping population (ICC4958 x Annigeri) with 40 SSR markers has revealed a QTL responsible for 33% of the phenotypic variation for root length and biomass. Two new mapping populations (ICC4958 x ICC1882, ICC8261 x ICC283), with more diverse genetic background have been phenotyped. These parental genotypes are currently being screened with existing and newly developed SSR markers for polymorphism. In the second approach, efforts have been initiated to undertake candidate gene sequencing-based association analysis using the reference collection of about 300 genotypes, selected based on the molecular diversity of the global composite collection of 3000 accessions at 50 SSR loci. In this direction, the known candidate drought responsive genes/transcription factors such as DREB1a, DREB2a, ASR1, ERECTA are being targeted to screen the reference collection. Analysis of marker genotyping data and sequence diversity data together with the phenotyping data on the mapping population and the reference collection for root traits will provide the molecular markers as well as superior alleles for drought avoidance traits that will enhance molecular breeding strategies for drought tolerance in chickpea.
