Antioxidant and Secondary Metabolite Responses in Wheat under Cereal Leaf Beetle (Oulema melanopus L.) Infestation

Abstract

AbstractWheat is one of the most important cereal crops grown in the Western Himalayas of India but its production is challenged by the insect “cereal leaf beetle (CLB)”. This study explores the impact of domestication and modern crop improvement on wheat's defense mechanisms against the CLB, a global threat to wheat cultivation. Sixteen diverse wheat genotypes having different ploidy levels were investigated, including wild wheat, landraces, mutants, advanced breeding lines, commercial varieties, and a Rye grass genotype. Genotypes with resistance genes, landraces, and wild wheat exhibited the lowest CLB infestation and oxidative damage. These genotypes displayed enhanced antioxidant enzyme activity, such as peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and polyphenol oxidase (PPO), reduced reactive oxygen species (ROS) production, and increased plant secondary metabolite (phenol and tannin) production upon CLB infestation. Resistant durum wheat demonstrated moderate responses and exhibited higher levels of flavonoid production. On the other hand, susceptible durum wheat genotypes, commercial variety Shalimar Wheat‐02 (SW‐2), showed high CLB infestation, ROS production, reduced antioxidant enzyme and secondary metabolite production. This may be because modern varieties like SW‐2 were not selected for insect resistance. These findings emphasize the significance of preserving genetic diversity from wild wheat and landraces to bolster wheat breeding programs against pests such as CLB. This study underscores the need to harness ancestral wheat lines to enhance insect pest resistance in modern wheat cultivars.