茶多酚对盐胁迫下小麦幼苗叶片生理特性的影响

Effects of tea polyphenols on physiological characteristics in leaves of wheat seedlings under salt stress

以春小麦"陇春30号"为实验材料,主要研究了150 mmol/L NaCl和不同浓度(25 mg/L和100 mg/L)茶多酚(tea polyphenols, TP)单独或复合处理对小麦幼苗叶片叶绿素含量、叶绿素荧光参数及过氧化氢(H2O2)产生等生理特性的影响。结果表明:(1)150 mmol/L NaCl单独处理导致小麦幼苗叶片叶绿素含量及光适应下实际光量子产量[actual light quantum yield,Y(II)]、光化学淬灭(photochemical quenching, qP)、光合电子传递效率(photosynthetic electron transfer efficiency, ETR)均降低,非光化学淬灭(non-photochemical quenching, NPQ)增大;TP单独处理不影响这些指标。(2)盐胁迫诱导细胞壁过氧化物酶(cell wall-peroxidase, cw-POD)、二胺氧化酶(diamine oxidase, DAO)和多胺氧化酶(polyamine oxidase, PAO)活性显著增高;低浓度TP使cw-POD活性显著增大,而DAO和PAO活性无显著变化;不同的是,高浓度TP不影响cw-POD活性,却使DAO和PAO活性显著减小。(3)与NaCl单独处理相比,TP的添加导致NaCl处理下小麦幼苗叶片叶绿素含量增加,最大光化学效率(maximal photochemical efficiency,Fv/Fm)和ETR值增大,而NPQ值、H2O2含量及cw-POD、DAO和PAO三种酶活性均降低。总之,TP有效地缓解了盐胁迫诱导的小麦幼苗叶绿素含量的减少及对PS II光合电子传递效率和光化学反应速率的抑制,增强了植物的光合能力,与此同时降低了cw-POD、DAO和PAO活性,减少了H2O2的产生,从而缓解盐胁迫对小麦幼苗造成的伤害,提高小麦幼苗对盐环境的耐受性。

Soil salinization, which can affect plant growth and agricultural output, is one of the worldwide environmental problems. The salt environment may impair chloroplast structure and decrease photosynthetic pigment content, thereby affecting the photosynthetic efficiency of plants. It may also alter the production of reactive oxygen species and thus affect the physiological characteristics in plants. Extracted from tea, tea polyphenols(TP) is an anti-aging, anti-tumor and anti-bacterial substance. It is mostly employed in animal research, but there are few studies on its effect on plant stress. Wheat cultivar Longchun 30 seedlings were used in present research to explore the effects of 150 mmol/L NaCl and different TP concentrations, in case of being applied or in combination, on such physiological characteristics as chlorophyll content, chlorophyll fluorescence characteristics and hydrogen peroxide(H2O2) generation. The results were follows: 1) 150 mmol/L NaCl treatment alone decreased chlorophyll content, actual light quantum yield [Y(II)], photochemical quenching(qP) and photosynthetic electron transfer efficiency(ETR) in wheat leaves, but improved non-photochemical quenching(NPQ). However, these indicators did not alter in response to TP treatment alone. 2) Salinity treatment resulted in the stimulation of cell wall-POD(cw-POD), diamine oxidase(DAO) and polyamine oxidase(PAO);low TP concentration significantly increased the activity of cw-POD, but did not have remarkable effects on DAO and PAO activities;in contrast, high TP concentration did not affect cw-POD activity, but significantly inhibited DAO and PAO activities. 3) Compared with NaCl treatment alone, the application of TP and NaCl in combination led to the increases of chlorophyll content, maximal photochemical efficiency(Fv/Fm) and ETR of photosystem II(PS II) in salinity-stressed seedlings, but the decreases of NPQ value, H2O2 content and the activities of cw-POD, DAO and PAO. In conclusion, while effectively alleviating the reduction of chlorophyll content and the inhibition of PSII photosynthetic electron transport rate and photochemical reaction rate in response to salinity stress, TP significantly reduced cw-POD, DAO and PAO activities as well as the incidence of H2O2 generation, thereby alleviating the damage on wheat seedlings caused by salt stress and improving their tolerance to salt environment.