UnderstandingUnravelling the genetic basis of resistance to maydis leaf blight and maturity-related traits in corn

Bhupender Kumar ¹ Pushpendra -rakhi7272@gmail.com ¹ Santosh Kumar ² Pardeep - Kumar ^1* Rakhi Singh ¹ Shrikant Yankanchi ¹ Debjyoti Sarkar ¹ Chhavi Nath ¹ Bahadur Singh Jat ¹ Pravin Kumar Bagaria ¹ Sumit Kumar Aggarwal ¹ Prahlad Piyal ¹ SB Singh ¹ Sujay Rakshit ^1,3 HS Jat ¹

• ¹ ICAR-Indian Institute of Maize Research, Ludhiana, India
• ² Indian Agricultural Research Institute (Jharkhand), Hazaribagh, Jharkhand, India
• ³ Department of Biotechnology, Indian Institute of Maize Research, Indian Institute of Agricultural Biotechnology (ICAR), Ludhiana, Punjab, India

Maize is one of the versatile and commercially produced crop used for food, feed, fodder, ethanol, oil, and industrial raw materials. Eventually, maize is affected by various diseases but among those, maydis leaf blight (MLB), is one of the serious diseases caused by Cochliobolus heterostrophus and responsible for yield losses up to 40%. While developing cultivars for a specific ecology, days to flowering and maturity are also important breeding traits to consider. Thus, understanding the genetic basis of MLB resistance specifically "O" race of the pathogen and maturity related traits is crucial to develop climate-resilient maize hybrids. This study aimed to determine the gene actions and their interactions for the MLB resistance and maturity related traits using six parameter model generation mean analysis (P1, P2, F1, BC1P1, BC1P2, and F2). Five experimental crosses were attended using resistant (R) (CML269-1, and P72c1 and Xbrasil1177-2) and susceptible (S) (HKIPC4B and ESM113) lines in R×S (1), S×R (2), R×R (1), and S×S (1) combinations. The susceptible lines were belonging to early (HKIPC4B) to medium (ESM113) maturity while resistant were of, medium (CML269-1) to late (P72c1XXbrasil1177-2) maturity group. These six genetic populations were screened under artificially created epiphytotic conditions at hot-spots site. In the analysis, MLB resistance showed a dominance genetic effect with a significant (P<0.01) additive × additive interactions. Maturity-related traits showed significant dominance genetic effects (P < 0.01), with dominance × dominance interactions, suggesting suitability of hybrid breeding for these traits. The estimated genes responsible for MLB resistance ranged from 0.002 to 5.78 per cross. In MLB resistance, broad and narrow sense heritability were found to be 91.9 and 84.3 percent, respectively, which indicated the possibility Formatted: Font: Not Italic, Complex Script Font: Not Italic of genetic improvement through selection. Disease response and maturity related traits were negatively correlated, suggesting that long duration genotypes are more resistant to disease than short duration. The detailed understating of gene actions can aid in designing breeding strategies to develop resistant cultivars with required duration for various stress prone ecologies.