CaHSP16.4, a small heat shock protein gene in pepper, is involved in heat and drought tolerance

Abstract

Environmental stress affects growth and development of crops, and reduces yield and quality of crops. To cope with environmental stressors, plants have sophisticated defense mechanisms, including the HSF/HSP pathway. Here, we identify the expression pattern of CaHSP16.4 in thermo-tolerant and thermo-sensitive pepper (Capsicum annuum L.) lines. Under heat stress, R9 thermo-tolerant line had higher CaHSP16.4 expression level than the B6 thermo-sensitive line. Under drought stress, expression pattern of CaHSP16.4 was dynamic. Initially, CaHSP16.4 was downregulated then CaHSP16.4 significantly increased. Subcellular localization assay showed that CaHSP16.4 localizes in cytoplasm and nucleus. In the R9 line, silencing of CaHSP16.4 resulted in a significant increase in malonaldehyde content and a significant reduction in total chlorophyll content, suggesting that silencing of CaHSP16.4 reduces heat and drought stresses tolerance. Overexpression of CaHSP16.4 enhances tolerance to heat stress in Arabidopsis. Under heat stress, the survival rate of CaHSP16.4 overexpression lines was significantly higher than wild type. Furthermore, under heat, drought, and combined stress conditions, the CaHSP16.4-overexpression lines had lower relative electrolytic leakage and malonaldehyde content, higher total chlorophyll content, and higher activity levels of superoxide dismutase, catalase, ascorbic acid peroxidase, and glutathione peroxidase compared to wild type. Furthermore, the expression levels of the stress response genes in the overexpression lines were higher than the wild type. These results indicate that the overexpression of CaHSP16.4 enhances the ability of reactive oxygen species scavenging under heat and drought stress.

A High Temperature Environment Regulates the Olive Oil Biosynthesis Network

“…Assuming that the ‘Barnea’ cultivar is more tolerant to heat stress compared to the ‘Souri’ cultivar in regard to fruit development and oil accumulation [ 36 ], suggests that induction of heat-shock proteins may contribute to the olive plant’s tolerance to heat stress. This assumption is in agreement with other studies which found that heat-shock proteins are involved in heat tolerance [ 26 , 47 , 48 ]. Analysis of OeHSP70 expression also showed the same pattern, in which the differences between the expression levels in the HT and the MT environments were much higher in the ‘Barnea’ cultivar than in the ‘Souri’.…”

Abiotic Stresses: General Defenses of Land Plants and Chances for Engineering Multistress Tolerance

“…Under stress challenges, drastically accumulated smHSPs are likely to seize non-native proteins to avoid their aggregation and then transfer them to ATP-dependent chaperones such as the HSP70 system for renaturation (see reviews Sun et al, 2002; Wang et al, 2004). It was newly reported that Arabidopsis transformed with HSP16.4 from pepper ( Capsicum annuum ) were less vulnerable to drought, heat and their combination, with the ROS scavenging enzymes being more active under stressful conditions (Huang et al, 2018).…”

Heat Shock Proteins: Dynamic Biomolecules to Counter Plant Biotic and Abiotic Stresses

“…Cytosolic HSP70 was involved in heat stress tolerance in Arabidopsis [148]. HSP70s have been studied under high temperature stress in a variety of plant crops; such as witch-grass and alfalfa [149,150]; vegetables like pepper, tomato, cabbage, potato; ornamental plants like chrysanthemum [151,152,153,154,155,156,157]; grain such as wheat [158]; and tea [159]. Xu et al, (2010) [160] observed the expression pattern of chloroplast HSP60, not only in normal conditions but, also, under high-temperature and drought situations.…”

“…It was responsible for Rubisco assembly, protection and also chloroplast development. Low molecular weight HSPs such as the HSP10, HSP20 and HSP40 families were up-regulated under high-temperature stress situations in various plant crops [5,152,161,162,163,164,165]. Some small HSPs were also genotype-specific and were up-regulated in resistant cultivars, such as foxtail millet, while some small HSPs were down-regulated in sensitive genotypes [53].…”