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<p>Northern corn leaf blight (NCLB), caused by <i>Setosphaeria turcica</i>, is a major foliar disease of maize that can cause up to 90% yield losses during severe epidemics. The North East Hill Region (NEHR) of India, a recognised hotspot for maize genetic diversity and NCLB prevalence, harbours valuable untapped sources of resistance. This study investigated the genetics of NCLB resistance using three biparental populations RM16 × SS1 (Pop 1), RM17 × SMA4 (Pop 2), and RM7 × ST24 (Pop 3) derived from NEHR landraces. Nine generations per population (P₁, P₂, F₁, F₂, F₃, BC₁, BC₂, BC₁-S₁, and BC₂-S₁) were evaluated under artificial epiphytotic conditions at Umiam, Meghalaya. Resistance was quantified using the Area Under the Disease Progress Curve (AUDPC). Cavalli’s joint scaling test (<i>P</i> &lt; 0.01) indicated the presence of digenic epistasis in all populations. Hayman’s six-parameter model revealed polygenic inheritance with significant additive effects and population-specific digenic epistatic interactions. In Pop 1, duplicate epistasis was observed along with very high narrow-sense heritability (h²ₙₛ = 0.99) and strong progeny predictability (R² = 40.1%) between F₂ and F₂:₃ generations. Pop 2 showed complementary epistasis with high heritability (h²ₙₛ = 0.94) although lower predictability (R² = 33.3%). In contrast, Pop 3 exhibited complementary epistasis accompanied by high dominance variance, lowest heritability (h²ₙₛ = 0.68) among the three populations, and poor predictability (R² = 12.4%). These findings demonstrate that the inheritance of NCLB resistance is population specific. Tailored breeding strategies are therefore required to effectively harness indigenous maize diversity for durable resistance. As elite germplasm may experience diminishing genetic gains due to narrowing diversity, the strategic utilisation of previously untapped alleles from NEHR landraces through population based approaches will be essential for sustained genetic gains in NCLB resistance.</p>

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Genetic Insights into NCLB Resistance in Maize (Zea Mays L.) Populations Derived from NEHR Landraces Using Generation Mean Analysis

  • 期刊论文

  • 发表日期：

    2026年5月30日

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  • Bipasha Datta,
  • S. Sugumar,
  • Violina Bharali,
  • Duddukur Rajasekhar,
  • Ramesh Chand,
  • Devyani Sen

摘要

Northern corn leaf blight (NCLB), caused by Setosphaeria turcica, is a major foliar disease of maize that can cause up to 90% yield losses during severe epidemics. The North East Hill Region (NEHR) of India, a recognised hotspot for maize genetic diversity and NCLB prevalence, harbours valuable untapped sources of resistance. This study investigated the genetics of NCLB resistance using three biparental populations RM16 × SS1 (Pop 1), RM17 × SMA4 (Pop 2), and RM7 × ST24 (Pop 3) derived from NEHR landraces. Nine generations per population (P₁, P₂, F₁, F₂, F₃, BC₁, BC₂, BC₁-S₁, and BC₂-S₁) were evaluated under artificial epiphytotic conditions at Umiam, Meghalaya. Resistance was quantified using the Area Under the Disease Progress Curve (AUDPC). Cavalli’s joint scaling test (P < 0.01) indicated the presence of digenic epistasis in all populations. Hayman’s six-parameter model revealed polygenic inheritance with significant additive effects and population-specific digenic epistatic interactions. In Pop 1, duplicate epistasis was observed along with very high narrow-sense heritability (h²ₙₛ = 0.99) and strong progeny predictability (R² = 40.1%) between F₂ and F₂:₃ generations. Pop 2 showed complementary epistasis with high heritability (h²ₙₛ = 0.94) although lower predictability (R² = 33.3%). In contrast, Pop 3 exhibited complementary epistasis accompanied by high dominance variance, lowest heritability (h²ₙₛ = 0.68) among the three populations, and poor predictability (R² = 12.4%). These findings demonstrate that the inheritance of NCLB resistance is population specific. Tailored breeding strategies are therefore required to effectively harness indigenous maize diversity for durable resistance. As elite germplasm may experience diminishing genetic gains due to narrowing diversity, the strategic utilisation of previously untapped alleles from NEHR landraces through population based approaches will be essential for sustained genetic gains in NCLB resistance.