Marker-trait association study for protein content in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is the second most important cool season food legume cultivated in arid and semiarid regions of the world. The objective of the present study was to study variation for protein content in chickpea germplasm, and to find markers associated with it. A set of 187 genotypes comprising both international and exotic collections, and representing both desi and kabuli types with protein content ranging from 13.25% to 26.77% was used. Twenty-three SSR markers representing all eight linkage groups (LG) amplifying 153 loci were used for the analysis. Population structure analysis identified three subpopulations, and corresponding Q values of principal components were used to take care of population structure in the analysis which was performed using general linear and mixed linear models. Marker-trait association (MTA) analysis identified nine significant associations representing four QTLs in the entire population. Subpopulation analyses identified ten significant MTAs representing five QTLs, four of which were common with that of the entire population. Two most significant QTLs linked with markers TR26.205 and CaM1068.195 were present on LG3 and LG5. Gene ontology search identified 29 candidate genes in the region of significant MTAs on LG3. The present study will be helpful in concentrating on LG3 and LG5 for identification of closely linked markers for protein content in chickpea and for their use in molecular breeding programme for nutritional quality improvement.

Achievements and prospects of genomics-assisted breeding in three legume crops of the semi-arid tropics

Advances in next-generation sequencing and genotyping technologies have enabled generation of large-scale genomic resources such as molecular markers, transcript reads and BAC-end sequences (BESs) in chickpea, pigeonpea and groundnut, three major legume crops of the semi-arid tropics. Comprehensive transcriptome assemblies and genome sequences have either been developed or underway in these crops. Based on these resources, dense genetic maps, QTL maps as well as physical maps for these legume species have also been developed. As a result, these crops have graduated from 'orphan' or 'less-studied' crops to 'genomic resources rich' crops. This article summarizes the above-mentioned advances in genomics and genomics-assisted breeding applications in the form of marker-assisted selection (MAS) for hybrid purity assessment in pigeonpea; marker-assisted backcrossing (MABC) for introgressing QTL region for drought-tolerance related traits, Fusarium wilt (FW) resistance and Ascochyta blight (AB) resistance in chickpea; late leaf spot (LLS), leaf rust and nematode resistance in groundnut. We critically present the case of use of other modern breeding approaches like marker-assisted recurrent selection (MARS) and genomic selection (GS) to utilize the full potential of genomics-assisted breeding for developing superior cultivars with enhanced tolerance to various environmental stresses. In addition, this article recommends the use of advanced-backcross (AB-backcross) breeding and development of specialized populations such as multi-parents advanced generation intercross (MAGIC) for creating new variations that will help in developing superior lines with broadened genetic base. In summary, we propose the use of integrated genomics and breeding approach in these legume crops to enhance crop productivity in marginal environments ensuring food security in developing countries.