Transcriptomic insights into the roles of HSP70-16 in sepal’s responses to developmental and mild heat stress signals

Abstract

Plant heat stress response (HSR) involves many heat shock proteins (HSPs), each might has distinct function. Thus, understanding of molecular bases of corresponding responses of each HSP in plant is essential for both basic and applied researches. While previous work focused dominantly on high temperature heat stress, studies on mild heat stress (about 5 °C over the optimal growth temperature) are rare. HSP70-16 is required for normal function of lateral sepals during flower opening at normal and mild heat stress, however, its underlying mechanism remains obscure. In this study, we compared transcriptomes of wild type and hsp70-16 sepals grown under normal (22 °C) and mild heat stress (27 °C) temperatures. Combined with weighted gene co-expression network analysis (WGCNA), we uncovered a HSP70-16 mediated molecular network that integrates both developmental and mild heat stress signals in Arabidopsis sepals, functioning to maintain protein homeostasis and metabolite homeostasis through a serial of network and hub genes including those encoding protein kinases, transcription factors, heat stress transcription factors, HSPs, hormones, reactive oxygen species, lipid/cuticle and cell wall components. Overall, the output of this study will provide an excellent resource for future characterization of HSPs to understand plant and heat stress interaction and obtain acquired thermos-tolerant plants.