Abstract
TILLING-by-sequencing (TBS) is a powerful approach for identification of novel alleles/mutations in candidate genes. In order to identify novel alleles in candidate genes, a TILLING population referred as “CaTILL”, comprising of 3,164 M3 lines was developed by treating ICC 4958, a chickpea (Cicer arietinum) genotype with 0.2% ethyl methane sulfonate (EMS). A set of 23 key candidate genes, involved in abiotic (drought and salinity), biotic (Ascochyta blight) stresses, flowering, symbiosis, nodulation and plant development were selected for allele mining using TBS approach. Of 78.62 GB sequence data generated by sequencing 80 barcode indexed Illumina libraries, 89.58 % of reads (on an average) were mapped to 23 candidate gene reference sequences. In total, 91 novel alleles/mutations were identified in 23 genes, of which 53 were C>T transitions and 38 were G>A transitions. The number of mutations identified per gene ranged from 1 (Late1) to 12 (Dmi2). Three mutations (one each in Nac3, Ca220909 and Ahc genes) were predicted to generate pre-mature stop codons, 40 mutations were mis-sense, 29 mutations were same-sense and 19 mutations were in introns. The mutation density in the population varied from one in 151.9 Kb (Ahc gene) to one in 3.9 Mb (Prodh gene) and the overall mutation density was one mutation per 708 Kb or ∼1042 mutations per genome. M4 lines suitable for mechanical harvesting, early flowering, abaxial pods, large seed size (45.78 gm 100-seed weight) and superior lines for several other agronomically important traits were identified.