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INCREASED RESISTANCE OF ARABIDOPSIS CPR5 MUTANT TO H₂O₂- INDUCED PHOTOOXIDATION

HUANG HONG-YING^1,2*,  LAI WEN-LING^1*, SONG LI-YING¹, SHU ZHAN^1,3, YANG CHENG-WEI ¹ AND PENG CHANG-LIAN^1**

Abstract: cpr5 is predicted to be a putative transmembrane protein involved in several cellular processes, including signal transduction plant defense and trichome development. The mutation of the cpr5 gene increases the resistance of Arabidopsis to pathogens. In this study, we show an In vitro increased resistance of cpr5 leaves to hydrogen peroxide-induced photooxidation. Both    fluorescence parameters (including Fv/Fm, ф_PSⅡ, qP and NPQ) and the activities of two anti-oxidative enzymes (SOD and APX) were used to evaluate the response of mutant and wild-type leaves to H₂O₂ treatment. During a 360-min., treatment, both mutant and wild-type leaves showed a time course dependent decrease trend in Fv/Fm values. However, the decrease rate for mutant leaves (0.046/min) was nearly twenty five-fold lower than that for wild-type leaves (0.101/min). The leaves of cpr5 dramatically delayed the reduction of ф_PSⅡ values and showed a different profile of ф_PSⅡ from the wild-type. At 240 min., of treatment, the value of ф_PSⅡ for the mutant leaves was nearly six-fold as that of the wild-type. The rates of cellular membrane leakage were constitutively lower in the cpr5 leaves than in the wild-type. In addition, the cpr5 leaves showed slightly higher activities of the SOD and APX enzymes than did the wild type. These results indicated that cpr5 mutant increased both anti-oxidative capability and the stability of PSII to H₂O₂-induced photooxidation. 

¹Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Guangdong Provincial Key Lab of Biotechnology for Plant Development, College of Life Sciences, South China Normal University, Guangzhou 510631,China,

²Department of Chemistry and Life science, Xiangnan College, Chenzhou, Hunan, 423000,China,

³Zealquest Laboratory for Ecological Research, Zealquest Scientific Technology Co. Ltd,  Shanghai 200333, China.