24-表油菜素内酯对农药处理下葡萄叶片光合特性和抗逆性的影响

Effects of 24-epibrassinolide on photosynthetic characteristics and resistance system in grape leaves after pesticide treatment

研究农药百菌清处理前用外源24-表油菜素内酯(24-epibrassinolide,EBR)预处理对酿酒葡萄品种‘赤霞珠’(Cabernet Sauvignon)光合特性、抗氧化系统以及农药降解代谢的影响,探讨EBR缓解农药对葡萄植株的伤害以及降低农药残留的作用。以酿酒葡萄品种赤霞珠盆栽苗为试材,研究EBR处理对百菌清胁迫下葡萄叶片光合气体交换参数、叶绿素荧光参数、活性氧和丙二醛含量、抗氧化物质含量、解毒酶活性以及叶片百菌清残留量的影响。结果表明:与对照相比,0.1 mg·L-1EBR单独处理可提高葡萄叶片的光合特性,CHT处理(600倍液的百菌清)抑制了叶片光合作用,与CHT处理相比,EBR+CHT处理可显著提高叶片净光合速率(Pn)、气孔导度(Gs)和胞间CO2浓度(Ci),以及叶片光合系统II(PSII)原初光能转换率(Fv/Fm)、实际光化学效率(ΦPSII)和光化学猝灭系数(q P);百菌清CHT处理使葡萄叶片过氧化氢(H2O2)、超氧阴离子(O·2)和丙二醛(MDA)含量显著升高,而EBR+CHT处理使H2O2、O·2和MDA含量分别比CHT处理降低32.5%、15.8%和4.7%,同时使还原型谷胱甘肽(GSH)和抗坏血酸(As A)含量显著高于CHT处理;0.1 mg·L-1EBR单独处理以及CHT处理均使叶片过氧化物酶(POD)、谷胱甘肽转移酶(GST)和谷胱甘肽还原酶(GR)活性有所提高,与CHT处理相比,EBR+CHT处理使叶片解毒酶活性进一步增强;EBR预处理加速了百菌清在叶片中的降解,显著降低了叶片农药残留量。研究得出:0.1mg·L-1EBR处理可促进葡萄叶片光合作用,提高抗氧化物质含量以及解毒酶活性,600倍液百菌清处理损害了葡萄叶片正常的光合作用和氧化还原平衡,外源0.1 mg·L-1EBR预处理能通过改善叶片光合特性,减少活性氧物质和丙二醛的积累以及提高解毒酶活性以促进百菌清降解,从而缓解农药对植株的伤害。

This study was conducted to determine the influences of exogenous EBR （24-epibrassinolide ） on the photosynthetic characteristics ,antioxidant systems and pesticide degradation metabolism of wine grape variety Cabernet Sauvignon ,and to explore EBR-induced alleviation of pesticide damage to the vines and its role in reducing pesticide residue .Using wine grape variety Cabernet Sauvignon （Vitis vinifera L .） potted seedlings as the experimental material , effects of EBR on the photosynthetic gas exchange characteristics ,chlorophyll fluorescence parameters ,reactive oxygen species and malondialdehyde contents ,antioxidant substances content ,detoxification enzyme activities and chlorothalonil residue in grape leaf were investigated .In comparison to the control ,0 .1 mg·L-1 EBR treatment alone could improve photosynthetic characteristics in grape leaf , and chlorothalonil treatment （600 times diluent ） had an inhibiting effect . Compared with the CHT treatment ,EBR＋CHT treatment could improve leaf net photosynthetic rate （ Pn） ,stomatal con-ductance （ Gs ） ,as well as intercellular CO2 concentration （ Ci ） significantly ,and it could also increase photosynthetic＆amp;nbsp;system II （PSII） ,photochemical conversion rate （ Fv/Fm） ,actual photochemical efficiency （ΦPSII） and photochemical quenching coefficient （ qP） significantly .Compared with the control ,chlorothalonil treatment could cause significant in-crease of hydrogen peroxide （H2 O2 ） ,superoxide anion （O ＆2 ） and malondialdehyde （MDA ） contents in grape leaf ,while EBR＋CHT treatment made them decreased by 33 .4% ,15 .8% and 6% respectively compared with CHT treatment and also it made glutathione （GSH） and ascorbic acid （AsA） contents increased by 5 .6% and 18 .2% on average .Exoge-nous 0 .1 mg·L-1 EBR treatment alone and CHT treatment could both enhance activities of peroxidase （POD ） ,glu-tathione-s-transferase （GST） and glutathione reductase （GR） in grape leaves significantly ,and EBR＋ CHT treatment could further enhance enzyme activities compared with CHT treatment .EBR pretreatment accelerated the degradation of chlorothalonil in leaves and reduced the pesticide residues significantly .In conclusion ,0 .1 mg·L-1 EBR treatment alone could promote grape leaf photosynthesis and increase antioxidant contents as well as detoxification enzyme activities ,and chlorothalonil treatment （600 times diluent ） damaged the normal photosynthesis and redox balance of grape leaves ,while exogenous 0 .1 mg·L-1 EBR pretreatment could improve leaf photosynthesis and reduce the accumulation of reactive oxy-gen species and MDA .It could also enhance detoxification enzyme activities to promote the degradation of chlorothalonil in leaves ,so as to mitigate the harm of pesticide on plants .