Heat Shock Proteins of Pistacia chinensis Could Promote Floral Development Under Drought Stress

Understanding the complex mechanisms underlying sex differentiation in dioecious plants is fundamental to elucidating plant reproductive strategies and their adaptive responses to environmental stresses. Pistacia chinensis, previously considered a strictly dioecious species, has been found to exhibit monoecy, with sex differentiation closely linked to environmental stress during floral development. However, the underlying molecular mechanisms remain poorly understood. This study explores the influence of environmental stress on sex differentiation with a focus on heat shock proteins (Hsps). Biochemical analyses revealed higher proline content and SOD activity in dioecious and monoecious females compared to males during the sex differentiation phase. Two key genes, PcHsp70-1 and PcHsp90, were identified as differentially expressed between sexes. Subcellular localization analysis showed that these proteins are present in both the nucleus and cytoplasm. Overexpression of PcHsp70-1 in Arabidopsis promoted bolting and flowering by upregulating flowering-related genes and also enhanced drought resistance. Similarly, PcHsp90 contributed to drought tolerance through multiple mechanisms. These findings suggest that Hsps play a key role in linking environmental stress responses to sex differentiation, thus laying the foundation for further research on plant–environment interactions and stress-adaptive mechanisms in P. chinensis.