The CsHSP17.2 molecular chaperone is essential for thermotolerance in Camellia sinensis

Abstract

Small heat shock proteins (sHSPs) play important roles in responses to heat stress. However, the functions of sHSPs in tea plants (Camellia sinensis) remain uncharacterized. A novel sHSP gene, designated CsHSP17.2, was isolated from tea plants. Subcellular localization analyses indicated that the CsHSP17.2 protein was present in the cytosol and the nucleus. CsHSP17.2 expression was significantly up-regulated by heat stress but was unaffected by low temperature. The CsHSP17.2 transcript levels increased following salt and polyethylene glycol 6000 treatments but decreased in the presence of abscisic acid. The molecular chaperone activity of CsHSP17.2 was demonstrated in vitro. Transgenic Escherichia coli and Pichia pastoris expressing CsHSP17.2 exhibited enhanced thermotolerance. The transgenic Arabidopsis thaliana exhibited higher maximum photochemical efficiencies, greater soluble protein proline contents, higher germination rates and higher hypocotyl elongation length than the wild-type controls. The expression levels of several HS-responsive genes increased in transgenic A. thaliana plants. Additionally, the CsHSP17.2 promoter is highly responsive to high-temperature stress in A. thaliana. Our results suggest that CsHSP17.2 may act as a molecular chaperone to mediate heat tolerance by maintaining maximum photochemical efficiency and protein synthesis, enhancing the scavenging of reactive oxygen species and inducing the expression of HS-responsive genes.

YocM a small heat shock protein can protect Bacillus subtilis cells during salt stress

“…). It has been shown many times that both heterologous and homologous overexpression of sHsp confers increased tolerance to heat or salt stress, indicating that although a sHsp has evolved its role under specific circumstances it still contributes to protein protection in general (Salas‐Muñoz et al ., ; Tian et al ., ; Kim et al ., ; Wang et al ., ).…”

“…Although heat and salt stress are connected e.g. during a drought, some sHsp have only been found to be upregulated during salt stress (Muthusamy et al ., ), whereas others are involved in both types of stress responses (Sarkar et al ., ; Ruibal et al ., ; Paul et al ., ; Li et al ., ; Sandhu et al ., ; Wang et al ., ; ; Zhao et al ., ).…”

Genome-wide characterization of tea plant (Camellia sinensis) Hsf transcription factor family and role of CsHsfA2 in heat tolerance

“…Tea plant, a perennial evergreen woody crop, has to cope with various abiotic stress during its lifecycle [57,58]. Expression profiles of CsHsf genes in tea plants (C. sinensis cv.…”

Genome-Wide Identification, Classification and Expression Analysis of the HSP Gene Superfamily in Tea Plant (Camellia sinensis)

“…Therefore, clarifying the mechanisms of tea plant response to heat and drought stress and identifying resistance genes are of great significance. Recently, four sHSP genes in tea plant were reported to play important roles in the process of tea plant response to heat stress [ 35 , 36 ]. However, other studies of HSPs in tea plant are extremely rare.…”