Biotechnology Bulletin ›› 2022, Vol. 38 ›› Issue (9): 158-166.doi: 10.13560/j.cnki.biotech.bull.1985.2021-1444

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Identification and Gene Functional Analysis of Salinity-hypersensitive Mutant ss2 in Rice

CHEN Guang1,2,3(), LI Jia4, DU Rui-ying1,2,3, WANG Xu1,2,3()   

  1. 1. Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences,Guangzhou 510640
    2. Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality,Ministry of Agriculture and Rural Affairs,Guangzhou 510640
    3. Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products,Guangzhou 510640
    4. College of Life and Environmental Sciences,Hangzhou Normal University,Hangzhou 311121
  • Received:2021-11-18 Online:2022-09-26 Published:2022-10-11
  • Contact: WANG Xu E-mail:chenguang0066@126.com;wangxuguangzhou@126.com

Abstract:

A library of ethane methyl sulfonate-induced Japonica rice mutants was screened under salinity conditions to explore putative salt stress-responsive genes,and a particularly salinity-sensitive mutant was identified. When challenged with 100 mmol/L NaCl,the mutant wilted heavily,became chlorotic and took up substantially more Na+ into shoots than its wild type(WT). The mutant plants' leaves suffered from a significantly greater decrease in both photosynthetic rate and leaf chlorophyll content than the WT plants' leaves after exposure to salinity,while the sucrose contents of the leaves increased and that in the roots decreased to 83% of WT ones. The expressions of several genes involved in sugar transport in the source leaves were down-regulated, indicating the impairment of sugar partitioning to the roots of the tissue organs. The lower sucrose contents in the sink tissues of the mutant could not meet the carbohydrate demands of plant growth,thereby the salinity tolerance reduced. The candidate gene was identified by map-based cloning and was denoted here as SS2(salinity sensitive 2). Functional complementation using the WT restored the salt sensitivity of the mutants. There was no significant difference between the performance of the complementary transgenic lines and the WT plants grown under salinity stress. The conclusion is that SS2 plays an important role in seedling growth and the response of rice to salinity stress by influencing sugar transport.

Key words: rice, mutant, map-based cloning, sucrose transport, salinity stress