Search for Indicators of Drought Tolerance at the Seed Filling Stage in Pea (Pisum sativum L.): From the Maternal Plant Response to Physiological and Metabolic Shifts in the Progeny Seeds

Due to oncoming climate changes, drought is recognized as one of the most important factors of crop yield losses. Water stress differentially affects plant longevity and productivity depending on the ontogenesis step. Specifically, drought occurring at the reproductive stage can reduce crop productivity and the quality of harvested seeds. Therefore, breeding new cultivars preserving both productivity and seed quality under drought conditions is urgently mandatory. However, no straightforward and reliable markers of drought tolerance are established for this ontogenesis step so far. It is generally unclear whether genetic differences between genotypes known as drought-tolerant and drought-sensitive can be traced in performance of the progeny mature seeds and their metabolic responses after rewatering. Therefore, here we address physiological, reproductive and seed metabolic responses in 29 pea genotypes varying in the degree of documented drought tolerance. The plants were subjected to transient irrigation withdrawal during pod formation. Based on the physiological data, metabolomes of nine most contrasting genotypes were profiled by GC-MS. The results revealed strong genotype-dependency of the stress-induced metabolic shifts, which only partly matched the physiological data. Thus, only complementation of physiological plant and seed traits with metabolic data might give access to interpretation of drought tolerance in grain legumes.