Cross-Generational Effect of Water Deficit Priming on Physiology of Peanut Plants Under Water Stress

Water deficit priming through regulated deficit irrigation has been shown to be beneficial for peanut cultivation, leading to improved water-use efficiency during the crop cycle and enhanced stress acclimation. The effects of priming using water deficit can be heritable, but little is known about stress priming effects on the physiology and growth of successive generations undergoing water stress. Two experiments were conducted to assess cross-generational priming by determining physiological and growth responses of offspring of primed and non-primed peanut plants of two genotypes, COC-041 and New Mexico Valencia C (NMV-C), both previously found to be strongly responsive to priming. Seeds were collected from parental plants subjected to mild water stress by regulated deficit irrigation (primed) or adequate irrigation (non-primed). These seeds were then planted, and the offspring were monitored for physiological and growth responses to water stress, including on a whole-plant basis using a high-throughput physiological phenotyping platform and on individual leaves by periodic single-leaf measurements. Measurements included whole-plant transpiration (plant-Tr), root water uptake, leaf transpiration, stomatal conductance and net CO₂ assimilation (leaf-Tr, leaf-g_s, and leaf-A), leaf water and osmotic potential (leaf-Ψ_w and leaf-Ψ_o), leaf osmotic adjustment, leaf relative water content (leaf-RWC) and cumulative plant-Tr. Offspring of both genotypes from primed parent plants had faster early establishment, with more uniform germination, and more rapid initial seedling growth compared to offspring from non-primed parent plants. Although offspring of both non-primed and primed plants of both genotypes exhibited a significant reduction of plant-Tr, gas exchange, leaf-Ψ_w, leaf-Ψ_o, and leaf-RWC when exposed to water stress, offspring of primed plants showed increased water use efficiency through reduced leaf-g_s, leaf-Tr and plant-Tr while maintaining leaf-A under water stress. Despite offspring of both primed and non-primed plants being susceptible to severe water stress, offspring of primed plants exhibited overall enhanced water use efficiency, leading to greater dry biomass production per gram of transpired water and a trend of less growth reduction due to water stress compared to offspring of non-primed plants, especially for the genotype COC-041. This study shows the potential of water deficit priming to promote cross-generational changes in physiological function under limited water availability, by enhancing crop stress acclimation in the next plant generation.