Intergenerational immune priming: Harnessing plant growth promoting rhizobacteria (PGPR) for augmented wheat protection against spot blotch

Abstract

Crop plants worldwide face various stresses that detrimentally impact their productivity. To ensure sufficient food production for the growing global population, it is essential to develop effective methods for safeguarding crops. Wheat, a critical crop for global food security, was the focus of this study. The objective was to identify a method to enhance the wheat plant's defense against stresses. Among the various approaches considered, defense priming emerged as a highly efficient method for crop protection. Plant defense priming involves a deliberate and controlled strategy employed by plants to enhance their protection against threats. It also allows for the transmission of the primed state to future generations through intergenerational inheritance. In this study, defense priming in wheat against spot blotch disease caused by Bipolaris sorokiniana was successfully achieved using two strains of plant growth-promoting rhizobacteria (PGPR). The performance of primed plants was evaluated based on growth parameters, disease phenotype, biochemical parameters, and yield-related traits. Primed plants exhibited superior performance compared to non-primed plants under disease conditions. Interestingly, the primed defense mechanisms were not immediately activated upon PGPR priming but were triggered upon subsequent pathogen challenge. This enhanced defense is evident through increased enzymatic antioxidants (SOD, Ascorbate peroxidase, Catalase), non-enzymatic antioxidants (total phenol content, proline, ascorbic acid), and defense-related enzyme activities, including peroxidases and Phenylalanine Ammonia Lyase (PAL), in primed plants compared to non-primed plants. This conservation of resources avoids unnecessary activation of defense mechanisms and wasteful consumption of photosynthates.Furthermore, the heritability of priming was investigated, and the offspring of PGPR-primed wheat demonstrated enhanced protection against B. sorokiniana compared to the offspring of non-primed wheat. Yield parameters were also improved in the progeny of primed wheat under biotic stress. Overall, this study highlights the potential of PGPR-mediated intergenerational defense priming as a cost-effective, long-lasting, chemical-free, and sustainable approach for disease management in agriculture. Implementing this strategy could effectively protect crops while minimizing fitness and environmental costs.