Gene Action and Combining Ability in wheat for drought tolerance

Abstract

Abstract

Wheat (Triticum aestivum L.) is a globally vital cereal crop, yet its productivity is increasingly constrained by drought stress, particularly in arid and semi-arid regions. Climate change intensifies this challenge, making the development of drought-resilient cultivars a critical breeding priority. Understanding the nature of gene action and combining ability underlying adaptive and yield-related traits is fundamental to genetic improvement. Quantitative genetic approaches, such as Line × Tester analysis, help distinguish between additive and non-additive gene effects, guiding the choice of breeding strategies. Additive gene action, associated with general combining ability (GCA), governs traits with high heritability such as relative water content (RWC) and cell membrane thermostability (CMT), enabling efficient selection in early segregating generations. Conversely, dominance and epistatic effects, reflected by specific combining ability (SCA), predominate in complex yield traits, emphasizing the value of heterosis and hybridization under stress conditions. Genetic variability derived from landraces, synthetic hexaploids, and elite cultivars provides essential allelic diversity for drought adaptation and water-use efficiency. Integrating conventional selection with molecular and physiological tools accelerates the identification of superior parents and hybrids. This review highlights that exploiting both additive and non-additive gene actions through balanced selection and hybrid breeding is key to achieving climate-resilient wheat improvement. Such integrative strategies ensure yield stability and sustainability in the face of global climate variability

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