外源5-ALA对干旱胁迫下茶树叶绿素合成和荧光特性及关键酶基因表达的影响

为探究外源5-氨基乙酰丙酸(5-ALA)在茶树幼苗响应干旱胁迫时对茶树叶绿素合成和荧光特性的调控机理,以舒茶早为试验材料,PEG-6000模拟干旱胁迫环境,喷施5-ALA进行处理,检测茶树幼苗叶片的叶绿素a、叶绿素b和总叶绿素含量,进一步测定叶片叶绿素荧光参数及关键酶基因的表达.结果显示,外源5-ALA显著提高干旱胁迫...

Effects of Exogenous 5-ALA on the Chlorophyll Synthesis and Fluorescence Characteristics and Gene Expression of Key Enzymes in Tea Plants under Drought Stress

In order to study the regulation mechanism of exogenous 5-aminolevulinic acid (5-ALA) on the chlorophyll synthesis and fluorescence characteristics of tea plants in response to drought stress, tea cultivar 'Shuchazao' was used as the experimental material in this study. Under PEG-6000 simulated drought stress environment and 5-ALA spraying pretreatment, the contents of chlorophyll a, chlorophyll b and total chlorophyll in tea seedling leaves were detected, and the chlorophyll fluorescence parameters and the expressions of key enzyme genes in tea leaves were further determined. The results show that exogenous 5-ALA significantly increased the contents of chlorophyll a, chlorophyll b and total chlorophyll in tea leaves under drought stress. Exogenous 5-ALA alleviated the decreases of maximum fluorescence (Fm), actual photochemical efficiency of PSⅡ Y(Ⅱ)], maximum photochemical quantum yield of PSⅡ (Fv/Fm), photochemical quenching coefficient (qP), potential activity of PSⅡ(Fv/Fo), photosynthetic electron transfer rate (ETR) of PSⅡ reaction center, and the increases of initial fluorescence (Fo) and nonphotochemical quenching coefficient (qN). At the same time, exogenous 5-ALA induced the expressions of chlorophyll synthesis (CsHEMA1, CsHEME1, CsLIN2) and carbon assimilation-related enzymes (CsSBPase, CsTK) in tea plant under drought stress. The study demonstrates that spraying exogenous 5-ALA can effectively alleviate the degradation of chlorophyll and damage to PSⅡ reaction center of tea leaves under drought stress, maintain the higher photosynthetic activity, and improve the photoprotection ability of tea leaves.