**6. Molecular marker resources**

With the advent of genomic research, new opportunities for genetic enhancement of complex traits like salinity and drought endurance have emerged. In comparison to traditional breeding, a combination of genomic approaches and molecular marker resources can significantly speed up the identification of individual-specific genes in breeding populations [78]. This explains the evolution of genetic marker technology from gel or hybridization approaches (DArT, SFP's) to sequence-based SSR and SNP markers. Diversity arrays technology (DArT), a hybridization based highly parallel genotyping protocol, has generated thousands of polymorphic loci in pigeonpea that were used for genetic diversity analysis and linkage mapping [6]. SNPs helps in the identification of haplotypes, and blocking such haplotypes would act as markers for the identification of relevant attributes utilizing allele mining approaches [79]. The 50 K Rice SNP50 array was developed for Illumina Infinium platform and has thousands of genome-wide SNPs with genic regions responsible for different genic regions. Further, this array was successfully used for variety verification and trait introgression. The 50 K Rice SNP50 chip plays an important role in both functional and genomics studies and molecular breeding [80, 81]. Similar analysis has been performed using a 62 K SNP array in pigeonpea germplasm. Incorporation of 746 disease resistance and defense response genes in the array with average 10 SNPs per

gene will be useful for pathologists and breeders in identifying genes for abiotic stress resistance in pigeonpea [82, 83].

Utilizing diverse genomics resources and enhanced genotyping platforms, molecular breeding techniques like MAS (marker-assisted selection), MABC (marker-assisted backcross breeding), GS, and multivariate adaptive regression splines (MARS) allow for the effective use of legume crop genetic resources that contain important alleles and genes. For instance, four molecular markers (ICCM0249, TAA170, GA24, and STMS11) have been transmitted by MABC for the creation of chickpea types that can tolerate drought [84–87]. Such markers have been developed by understanding the genome-wide sequence variations and are effectively utilized for allele mining, characterizing germplasm for genetic improvement and genetic mapping of important agronomics traits.
