Introgression of drought tolerance root traits into Kenyan commercial chickpea varieties using marker assisted backcrossing

Abstract

Roots play critical roles in enhancing drought tolerance, more so under terminal drought conditions. The objective of this study was to introgress drought tolerant root traits into Kenyan chickpea varieties through marker assisted backcrossing (MABC). Eight simple sequence repeat (SSR) markers, linked to quantitative trait loci (QTL) for root traits, were used to screen parents at ICRISAT in India, and 1144 single nucleotide polymorphic (SNPs) markers at Legume Genomics Centre in the United Kingdom. Crosses were made between two selected varieties, ICCV 92944 (Chania Desi II) and ICCV 00108 (LDT 068); and ICC 4958, QTL donor parent. Polymorphic SSR and SNP markers were used to select offspring with root QTL at F1, BC1F1, and BC2F1, and later advanced to BC2F3. BC2F3 families were evaluated for root traits at Egerton University in Kenya in a pot experiment under rain shelter. The BC2F3 families were significantly (P<0.05) different for root dry weight (RDW), shoot dry weight (SDW), total plant dry weight (PDW), and root to shoot dry weight (R/S) ratio (R/S) for Chania Desi II x ICC 4958; while R/S was significantly different for LDT 068 x ICC 4958. Root length density (RLD) and RDW were positively and significantly (P<0.05) correlated with most of the traits, indicating its usefulness in the indirect selection of these traits. The utilisation of MABC is an effective and efficient method of introgressing complex root traits into commercial lines, expected to improve yields under drought. There is need for deployment of marker-assisted breeding in difficult to phenotypically select traits.