Male and female poplars exhibited sex-specific differences in metabolic and transcriptional responses to two levels of water deficit

Abstract

Dioecious plant species exhibit sexual dimorphism in morphology and physiology under water deficit conditions, but the metabolic and molecular mechanisms underlying such differences are barely explored. In this study, we integrated metabolome and transcriptome analyses of female and male full-sibs of Populus deltoides that featured different drought tolerance in response to moderate and severe water shortage conditions. The results showed that male poplars had higher chlorophyll content and photosynthetic capacity, which result in a better growth performance than female poplars under drought conditions. The metabolome profiling revealed that both the quantification and qualification of differentially expressed metabolites in male poplars were higher than those in females. The transcriptome analysis revealed that the KEGG pathway was enriched in plant hormone signal transduction and carotenoid biosynthesis pathway in both male and female poplars under water deficiency. Moreover, the number of differentially expressed genes (DEGs) that were altered by plant sex was much lower than that by drought treatment. Simultaneously, most of these DEGs were up-regulated in male poplars, especially the key genes that involve in ABA synthetic pathway. The results revealed the metabolic and molecular mechanisms underlying the better ability of drought resistance observed in male poplar plants.