Marker-assisted introgression of leaf rust resistance from Triticum turgidum cv. Trinakria to bread wheat variety HD3086

Abstract

Using marker-assisted backcross breeding (MABB), the extensively cultivated but vulnerable to leaf rust Indian bread wheat variety HD3086 was improved with the LrTrk leaf rust resistance gene. After its release, HD3086 developed a vulnerability against leaf rust. In the present study, HD3086 was introgressed with LrTrk, a leaf rust resistance gene from the Trinakria genotype of durum wheat. The population comprising F₁, BC₁F₁, BC₂F₁, and BC₂F₂ plants was developed by crossing and backcrossing Trinakria with HD3086. Foreground selection targeting LrTrk and background analysis for recovering the recurrent parent genome (RPG) were conducted in the BC₁F₁ and successive generations. The LrTrk-linked SSR marker, Xgwm234, was utilized for foreground analysis, while SSRs exhibiting significant polymorphism between parents were used to determine the background recovery in all generations. Finally, 20 LrTrk positive BC₂F₃ NILs displaying the highest background recovery with RPG (97.23-98.67%) also showed differential leaf rust response with pathotype 77-5 of P. triticina. Based on the RPG recovery and leaf rust score, BC₂F₃ NILs have also been subjected to field evaluation for yield and yield-contributing traits. The study revealed non-significant differences in PH, SL, TN, SPS, and GYs of most BC₂F₃ NILs compared to recurrent parent HD3086. Overall, the study unveils the practical utility of MABB in leaf rust breeding for developing resistant cultivars in the background of elite and popular wheat varieties with relatively higher precision and speed.