A tomato chloroplast-targeted DnaJ protein protects Rubisco activity under heat stress

Abstract

Photosynthesis is one of the biological processes most sensitive to heat stress in plants. Carbon assimilation, which depends on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is one of the major sites sensitive to heat stress in photosynthesis. In this study, the roles of a tomato (Solanum lycopersicum) chloroplast-targeted DnaJ protein (SlCDJ2) in resisting heat using sense and antisense transgenic tomatoes were examined. SlCDJ2 was found to be uniformly distributed in the thylakoids and stroma of the chloroplasts. Under heat stress, sense plants exhibited higher chlorophyll contents and fresh weights, and lower accumulation of reactive oxygen species (ROS) and membrane damage. Moreover, Rubisco activity, Rubisco large subunit (RbcL) content, and CO2 assimilation capacity were all higher in sense plants and lower in antisense plants compared with wild-type plants. Thus, SlCDJ2 contributes to maintenance of CO2 assimilation capacity mainly by protecting Rubisco activity under heat stress. SlCDJ2 probably achieves this by keeping the levels of proteolytic enzymes low, which prevents accelerated degradation of Rubisco under heat stress. Furthermore, a chloroplast heat-shock protein 70 was identified as a binding partner of SlCDJ2 in yeast two-hybrid assays. Taken together, these findings establish a role for SlCDJ2 in maintaining Rubisco activity in plants under heat stress.

Individual and interactive effects of drought and heat on leaf physiology of seedlings in an economically important crop

“…During the 7-day heat wave period, leaf senescence and reduction in chlorophyll content were observed in well watered plants, which is supported by other studies (Marchand et al 2006; Wang et al 2015). For example, Wang et al (2015) found that tomato grown under 42 °C for 24 h had significantly lower chlorophyll content than that grown under 25 °C. In the present study, the very high leaf temperature ( i.e .…”

The DnaJ Gene Family in Pepper (Capsicum annuum L.): Comprehensive Identification, Characterization and Expression Profiles

“…Previous researchers had reported that the DnaJ protein was involved in plant response to heat and drought stresses (Xia et al, 2014; Wang et al, 2015). To further comprehend the putative roles of CaDnaJ genes in pepper response to HS, expressions patterns of CaDnaJ genes under HS treatment conditions were analyzed by qRT-PCR.…”

Whirly1 enhances tolerance to chilling stress in tomato via protection of photosystem II and regulation of starch degradation

“…Immuno-blotting was conducted as described by Wang et al (2015). The anti-FLAG antibody was purchased from Sigma-Aldrich (A8592).…”