Abstract
Pepper is a thermophilic crop, shallow-rooted plant that is often severely affected by abiotic stresses such as heat, salt, and drought. The growth and development of pepper is seriously affected by adverse stresses, resulting in decreases in the yield and quality of pepper crops. Small heat shock proteins (s HSPs) play a crucial role in protecting plant cells against various stresses. A previous study in our laboratory showed that the expression level of CaHSP18.1a was highly induced by heat stress, but the function and mechanism of CaHSP18.1a responding to abiotic stresses is not clear. In this study, we first analyzed the expression of CaHSP18.1a in the thermo-sensitive B6 line and thermo-tolerant R9 line and demonstrated that the transcription of CaHSP18.1a was strongly induced by heat stress, salt, and drought stress in both R9 and B6, and that the response is more intense and earlier in the R9 line. In the R9 line, the silencing of CaHSP18.1a decreased resistance to heat, drought, and salt stresses. The silencing of CaHSP18.1a resulted in significant increases in relative electrolyte leakage (REL) and malonaldehyde (MDA) contents, while total chlorophyll content decreased under heat, salt, and drought stresses. Overexpression analyses of CaHSP18.1a in transgenic Arabidopsis further confirmed that CaHSP18.1a functions positively in resistance to heat, drought, and salt stresses. The transgenic Arabidopsis had higherchlorophyll content and activities of superoxide dismutase, catalase, and ascorbate peroxidase than the wild type (WT). However, the relative conductivity and MDA content were decreased in transgenic Arabidopsis compared to the wild type (WT). We further showed that the CaHSP18.1a protein is localized to the cell membrane. These results indicate CaHSP18.1a may act as a positive regulator of responses to abiotic stresses.
Highlights
Introduction published maps and institutional affilPlants can tolerate considerable biotic and abiotic stresses in their complex and changing environments, including drought, high salt, extreme temperatures, and oxidation [1,2].To mitigate stresses, plants have developed several protective mechanisms
We found that the green fluorescence signal of pVBG2307: CaHSP18.1a: GFP was detected in the cell membrane (Figure 2A), while the fluorescence of the empty pVBG2307: GFP vector was distributed throughout the cell (Figure 2B), indicating that CaHSP18.1a is localized to the cell membrane
We first analyzed the expression of CaHSP18.1a in R9 and B6 pepper lines and demonstrated that CaHSP18.1a was expressed when induced by abiotic stress factors such as high temperature, drought, and high salinity
Summary
Introduction published maps and institutional affilPlants can tolerate considerable biotic and abiotic stresses in their complex and changing environments, including drought, high salt, extreme temperatures, and oxidation [1,2].To mitigate stresses, plants have developed several protective mechanisms. Plants can tolerate considerable biotic and abiotic stresses in their complex and changing environments, including drought, high salt, extreme temperatures, and oxidation [1,2]. Heat shock proteins (HSPs) can maintain protein homeostasis and prevent or repair the misfolding of proteins in abiotic stresses response. Plant HSPs play critical roles in the folding, transport, degradation, and assembly of proteins under normal and stress conditions [6]. In response to high temperatures, plant cells dramatically increase the concentrations of HSPs to prevent heat-related damage and increase plant thermotolerance [7]. HSPs are involved in plant growth and development under normal conditions, including the growth of flowers and seeds as well as fruit set, development [8], tuberization [9], and nutrient uptake [10].
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