Genomics-assisted breeding in four major pulse crops of developing countries: present status and prospects

The global population is continuously increasing and is expected to reach nine billion by 2050. This huge population pressure will lead to severe shortage of food, natural resources and arable land. Such an alarming situation is most likely to arise in developing countries due to increase in the proportion of people suffering from protein and micronutrient malnutrition. Pulses being a primary and affordable source of proteins and minerals play a key role in alleviating the protein calorie malnutrition, micronutrient deficiencies and other undernourishment-related issues. Additionally, pulses are a vital source of livelihood generation for millions of resource-poor farmers practising agriculture in the semi-arid and sub-tropical regions. Limited success achieved through conventional breeding so far in most of the pulse crops will not be enough to feed the ever increasing population. In this context, genomics-assisted breeding (GAB) holds promise in enhancing the genetic gains. Though pulses have long been considered as orphan crops, recent advances in the area of pulse genomics are noteworthy, e.g. discovery of genome-wide genetic markers, high-throughput genotyping and sequencing platforms, high-density genetic linkage/QTL maps and, more importantly, the availability of whole-genome sequence. With genome sequence in hand, there is a great scope to apply genome-wide methods for trait mapping using association studies and to choose desirable genotypes via genomic selection. It is anticipated that GAB will speed up the progress of genetic improvement of pulses, leading to the rapid development of cultivars with higher yield, enhanced stress tolerance and wider adaptability

Inheritance and tagging of <em>Tomato leaf curl virus </em>(ToLCV) disease resistance genes in exotic tomato genotypes

357-363In the present investigation resistance genes have been introgressed into cultivated tomato from wild relatives, Solanum hirsutum accession (EC-520061) and an introgression cultivar of Solanum chilense (EC-538408) which showed a high level of resistance against tomato leaf curl Gujarat virus (Varanasi strain). Genetic studies revealed that one tomato leaf curl virus (ToLCV) disease resistance gene is present in EC-520061 and EC-538408 that segregated independently in their progenies. Furthermore, it has been identified that simple sequence repeats (SSR) markers SSR-306 was associated with the (ToLCV) disease resistance genes in tomato cultivar EC-538408 (derived from S. chilense), and SSR-218 was associated with a ToLCV disease resistance gene of EC-520061 (S. hirsutum). Both ToLCV resistance linked SSR markers were highly reproducible and effective in the identification of ToLCV disease resistance genes in the segregating populations and thus it is concluded that these two SSR markers could be used effectively in marker assisted selection for ToLCV disease resistance breeding program

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Not AvailableSeed traits present important breeding targets for enhancing grain yield and quality in various grain legume crops including pigeonpea. The present study reports significant genetic variation for six seed traits including seed length (SL), seed width (SW), seed thickness (ST), seed weight (SWT), electrical conductivity (EC) and water uptake (WU) among Cajanus cajan (L.) Millspaugh acc. ICPL 20340 and Cajanus scarabaeoides (L.) Thouars acc. ICP 15739 and an F2 population derived from this interspecific cross. Maximum phenotypic values recorded for the F2 population were higher than observed in the parent ICPL 20340 [F2 max vs ICPL 20340: SW (7.05 vs 5.38), ST (4.63 vs 4.51), EC (65.17 vs 9.72), WU (213.17 vs 109.5)], which suggested contribution of positive alleles from the wild parent, ICP 15739. Concurrently, to identify the QTL controlling these seed traits, we assayed two parents and 94 F2 individuals with 113 polymorphic simple sequence repeat (SSR) markers. In the F2 population, 98 of the 113 SSRs showed Mendelian segregation ratio 1:2:1, whereas significant deviations were observed for 15 SSRs with their χ2 values ranging between 6.26 and 20.62. A partial genetic linkage map comprising 83 SSR loci was constructed. QTL analysis identified 15 marker-trait associations (MTAs) for seed traits on four linkage groups i.e. LG01, LG02, LG04 and LG05. Phenotypic variations (PVs) explained by these QTL ranged from 4.4 (WU) to 19.91% (EC). These genomic regions contributing significantly towards observed variability of seed traits would serve as potential candidates for future research that aims to improve seed traits in pigeonpea.Not Availabl