Introgressing cry1Ac for Pod Borer Resistance in Chickpea Through Marker-Assisted Backcross Breeding

• Published in: Frontiers in genetics Vol. 13; p. 847647
• Main Authors: Kaur, Ajinder, Sharma, Urvashi, Singh, Sarvjeet, Singh, Ravinder, Vikal, Yogesh, Singh, Satnam, Malik, Palvi, Kaur, Khushpreet, Singh, Inderjit, Bindra, Shayla, Sarmah, Bidyut Kumar, Sandhu, Jagdeep Singh
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 12.04.2022
• Subjects: Cicer arietinum; Genetics; Helicoverpa armigera resistance; marker-assisted backcross breeding; Mendelian inheritance; transgene introgression; marker-assisted backcross breeding; transgene introgression; Mendelian inheritance; Helicoverpa armigera resistance; Cicer arietinum
• ISSN: 1664-8021; 1664-8021
• DOI: 10.3389/fgene.2022.847647

The gram pod borer is a major constraint to chickpea ( L.) production worldwide, reducing crop yield by up to 90%. The constraint is difficult to overcome as chickpea germplasm including wild species either lacks pod borer resistance or if possessing resistance is cross-incompatible. This study describes conversion of elite but pod borer-susceptible commercial chickpea cultivars into resistant cultivars through introgression of cry1Ac using marker-assisted backcross breeding. The chickpea cultivars (PBG7 and L552) were crossed with pod borer-resistant transgenic lines (BS 100B and BS 100E) carrying cry1Ac that led to the development of BC F , BC F , BC F , BC F , BC F , and BC F populations from three cross combinations. The foreground selection revealed that 35.38% BC F and 8.4% BC F plants obtained from Cross A (PBG7 × BS 100B), 50% BC F and 76.5% BC F plants from Cross B (L552 × BS 100E), and 12.05% BC F and 82.81% (average) BC F plants derived from Cross C (PBG7 × BS 100E) carried the cry1Ac gene. The bioassay of backcross populations for toxicity to . displayed up to 100% larval mortality. BC F and BC F populations derived from Cross B and BC F population from Cross C segregated in the Mendelian ratio for cry1Ac confirmed inheritance of a single copy of transgene, whereas BC F and BC F populations obtained from Cross A and BC F population from Cross C exhibited distorted segregation ratios. BC F plants of Cross A and Cross B accumulated Cry1Ac protein ranging from 11.03 to 11.71 µgg in leaf tissue. Cry1Ac-positive BC F plants from Cross C demonstrated high recurrent parent genome recovery (91.3%) through background selection using SSR markers and phenome recovery of 90.94%, amongst these 30% plants, were homozygous for transgene. The performance of BC F progenies derived from homozygous plants was similar to that of the recurrent parent for main agronomic traits, such as number of pods and seed yield per plant. These progenies are a valuable source for . resistance in chickpea breeding programs.