Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2022, Vol. 43 ›› Issue (11): 2199-2206.DOI: 10.3969/j.issn.1000-2561.2022.11.003

• Special Topic of Natural Rubber • Previous Articles     Next Articles

Salt Stress Response and Functional Indentification of HbICEs from Rubber Tree

LI Yan, YANG Shuguang, SHI Minjing, TIAN Weimin()   

  1. Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences / Key Laboratory of Biology and Genetic Resources of Rubber Tree, Ministry of Agriculture and Rural Affairs / Hainan Key Laboratory for Cultivation & Physiology of Tropical Crops, Haikou, Hainan 571101, China
  • Received:2022-05-17 Revised:2022-07-12 Online:2022-11-25 Published:2022-12-12
  • Contact: TIAN Weimin
  • About author:*TIAN Weimin,E-mail:wmtian@163.com


ICE (inducer of CBF expression), the MYC (myelocytomatosis)-like bHLH (basic helix-loop-helix) transcription factor, plays an important role in regulating the responses of plants to abiotic stresses such as low temperature, drought, and high salt. In this study, the expression patterns of rubber tree ICE genes were analyzed by qPCR. The expression of five HbICEs were up-regulated in rubber tree seedlings upon salt stress, HbICE2, HbICE3, HbICE4 and HbICE5 were significantly up-regulated under salt stress for 2 h. At 4 h of salt stress, the expression of HbICE4 and HbICE5 reached the maximum with the most up-regulated level of HbICE4. Under salt stress for 4-24 h, HbICE3 was significantly down regulated. The expression of HbICE1 had no obvious change before 4 h of salt stress, but increased significantly after 8 h. Therefore, all five HbICE genes may participate in the salt stress response of rubber tree. Overexpression of HbICEs, especially HbICE4, led to an enhanced salt-tolerance of transgenic Arabidopsis based on survival rate, average fresh and dry weight per plant. Under salt stress, all wild-type Arabidopsis wilted. The survival rate of HbICE4 overexpressing Arabidopsis was 96.29%, the average fresh weight per plant was 0.03 g, and the average dry weight per plant was 0.0035 g, the three growth parameters of HbICE4 overexpressing plants were the highest among the transformed strains of rubber tree HbICE genes. Compared with the physiological indexes before salt stress, the relative conductivity of WT and HbICEs transgenic plants increased significantly under salt stress, and the chlorophyll content and relative water content decreased significantly. Among them, relative conductivity increase of HbICE4 transformed Arabidopsis was the smallest, and the decrease of SPAD value (chlorophyll content) and relative water content was the smallest. Therefore, the enhanced salt-tolerance was associated with lower relative conductivity, a physiological parameter for evaluating membrane system stability, as well as higher chlorophyll content and relative water content in comparison to those of WT. Salt stress leads to the damage of plant cell membrane system, resulting in the decrease of water content, the destruction of chloroplasts and the degradation of chlorophyll. The membrane system of plants overexpressing HbICE4 was slightly damaged under salt stress, delaying the decrease of water content and the degradation of chlorophyll. Rubber tree HbICEs can not only improve the cold and drought tolerance of transgenic plants, but also improve the salt-tolerance of transgenic plants. This study would deepen the understanding of the biological function of rubber tree HbICEs, and provide candidate target genes for improving salt-tolerance of crops.

Key words: Hevea brasiliensis Muell. Arg., inducer of CBF expression, salt tolerance, functional identification

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