Genetic analysis of maydis leaf blight resistance in subtropical maize ( Zea mays L.) germplasm
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Ó Indian Academy of Sciences (0123456789().,-volV) (0123456789().,-volV)
RESEARCH ARTICLE
Genetic analysis of maydis leaf blight resistance in subtropical maize (Zea mays L.) germplasm B. JEEVAN1,2, ROBIN GOGOI1* , DEVENDER SHARMA2, C. MANJUNATHA1,3, H. RAJASHEKARA1,2, DAMA RAM1,4, K. K. MISHRA2 and M. G. MALLIKARJUNA5* 1Division
of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi 110 012, India Parvatiya Krishi Anusandhan Sansthan, Almora 263 601, India 3Regional Station, ICAR-Indian Agricultural Research Institute, Wellington (Nilgiris) 643 231, India 4College of Agriculture, Agriculture University, Jodhpur 342 304, India 5Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi 110 012, India 2ICAR-Vivekananda
*For correspondence. E-mail: Robin Gogoi, [email protected]; M. G. Mallikarjuna, [email protected]. Received 3 June 2020; revised 24 July 2020; accepted 20 August 2020 Abstract. Knowledge on the genetics of maydis leaf blight (MLB) is crucial to breed the resistant maize cultivars to combat disease epidemics as a sustainable and cost-effective approach. The present investigation was framed to understand the genetics of MLB resistance in subtropical maize. Two contrasting genotypes CM119 (susceptible) and SC-7-2-1-2-6-1 (resistant) were used to generate six genetic populations, namely P1, P2, F1, F2, BC1P1 and BC1P2, and evaluated in three target environments for MLB resistance under artificial epiphytotic condition. The CM119 and SC-7-2-1-2-6-1 showed susceptible and resistant reactions with mean disease reaction of 3.89–3.98 and 1.88–2.00, respectively. The derived generations, namely F1, F2, BC1P1 and BC1P2 showed mean disease reaction of 2.15–2.28, 2.44–2.51, 2.19–2.24 and 2.22–2.28, respectively in the test locations. The segregating generations (F2: 0.35–0.37; BC1P1: 0.24–0.29 and BC1P2: 0.17–0.20) showed variation for MLB disease resistance over the parental and first filial generations (P1: 0.11–0.17; P2: 0.08–0.13 and F1: 0.12–0.14). The genetic analysis of MLB resistance revealed the nonallelic interactions of duplicate epistasis type across the test locations. Among the gene interactions, dominance 9 dominance [l] effect was predominant over additive 9 additive [i] and additive 9 dominance [j] effects. The segregation analysis and the prediction of the number of major loci revealed at least two major genes associated with MLB tolerance in subtropical maize. Our investigation paved the foundation for the improvement of subtropical maize germplasm of MLB resistance. Keywords. gene action; genetic effects; generation mean analysis; inheritance pattern; maize; maydis leaf blight; resistance breeding; Cochliobolus heterostrophus.
Introduction Maydis leaf blight (MLB) disease or southern corn leaf blight (SCLB), caused by Cochliobolus heterostrophus (Drech.) [(Bipolaris maydis (Nishik. and Miyake) Shoemaker)] is one of the potential threats to global maize production. The MLB on maize distributed across the globe; however, shows higher incide
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