PRIL_A, PRIL_B and PRIL_C: Pigeonpea Recombinant Inbred Line Mapping Populations Segregating for Resistance to Fusarium Wilt and Sterility Mosaic Disease

Pigeonpea [Cajanus cajan (L) Millsp] bi-parental populations segregating for various traits of interest are being developed. The three most advanced populations, named PRIL_A, PRIL_B and PRIL_C (Pigeonpea Recombinant Inbred Line, population A, B and C) have reached F6 generation. PRIL_A: derived from the cross ICPB 2049 x ICPL 99050 segregates for fusarium wilt (FW), 329 lines. PRIL_B: derived from the cross ICPL 20096 x ICPL 332 segregates for FW and sterility mosaic disease (SMD), 342 lines. PRIL_C: derived from the cross ICPL 20097 × ICP 8863 segregates for SMD, 366 lines. Marker genotyping of the parental lines, however, showed low level of genetic variation. After screening over 4,616 (3,000 simple sequence repeats (SSRs) and 1,616 single nucleotide polymorphism (SNPs)) markers on parental genotypes of each mapping population, a total of 159 (104 SSRs and 55 SNPs), 80 (52 SSRs and 28 SNPs) and 157 (143 SSRs and 14 SNPs) markers were found polymorphic for ICPB 2049 vs ICPL 99050, ICPL 20096 vs ICPL 332 and ICPL 20097 vs ICP 8863, respectively. The polymorphic markers will be used for constructing genetic linkage maps. The populations will be screened for FW and SMD in 2012-13, while marker-trait association analysis will also be conducted to understand the genetic basis of resistance to these diseases. Further selection from the above indicated mapping populations during 2011-12, on an effort initiated in 2010, resulted in 28 lines with high yield (up to 2.4 t/ha) and disease resistanc

Genotype x environment interaction for biometrical traits in pigeonpea (Cajanus cajan L. Millsp.) under varying spacings

Twenty eight genotypes of pigeonpea, which includes promising lines as well as randomly selected varietieswere studied for their G X E interaction. The genotypes were sown in a three different environments were madeavailable by three spacings at 60, 90 and 120 cm. .Pigeonpea genotypes BDN 2001-6, Phule T 11-39, JJ 65, GT 1,BSMR 736 and LRG 41 are considered to be more desirable ones, as they satisfied the criteria suggested by Eberhart andRussell (1966) for stability over three different spacings

Single nucleotide polymorphism genotyping for breeding and genetics applications in chickpea and pigeonpea using the BeadXpress platform

Single nucleotide polymorphisms (SNPs) are ideal molecular markers due to their higher abundance. Although several types of genotyping platforms for assaying large number of SNPs are available, in cases such as marker-assisted selection, where few markers are required for genotyping a set of potential lines, high-throughput SNP genotyping platforms (e.g., iScan or Infinium) may not be cost effective. In this scenario, GoldenGate assays based on VeraCode technology using Illumina BeadXpress seems to be the most cost-effective platform. The objective of this study was to develop cost-effective SNP genotyping platforms in chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan L.). Two sets of SNPs, one each for chickpea (96 SNPs) and pigeonpea (48 SNPs), were developed and tested by genotyping 288 diverse genotypes from respective reference sets. The SNPs selected for the oligo pool assays had high transferability to crop wild relative species. The mean polymorphism information content value of assayed SNP markers was 0.31 and 0.32 in chickpea and pigeonpea, respectively. No unique pattern was observed in the chickpea reference set whereas two major groups were observed in the case of the pigeonpea reference set. The Illumina BeadXpress platform assays developed for chickpea and pigeonpea are highly informative and cost effective for undertaking genetic studies in these legume species

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