作 者 ：巩文秀,马力,张存莉

期 刊 ：植物营养与肥料学报 2016年 22卷 2期 页码：565-571

关键词：拉肖皂苷C；黄瓜幼苗；油菜素甾醇；干旱胁迫；

Keywords:laxogenin C, cucumber seedling, brassinosteroids, drought stress,

摘 要 ：【目的】拉肖皂苷C(LG-C)与茶甾酮类油菜素甾醇化合物结构相似,都含有3-糖苷基-6-酮等活性官能团,表现出一定的油菜甾醇类植物激素的活性,且LG-C具有含量丰富、 制备简单及成本低的优点。但是LG-C对于植物抗旱生理效应的研究迄今未见报道,因此本试验研究了LG-C对干旱胁迫下黄瓜幼苗的生理效应,以期为LG-C后续的研究奠定基础。【方法】以黄瓜幼苗为试材,进行了喷施拉肖皂苷C(LG-C)的盆栽试验。设置了基质含水量分别为田间持水量的80%(对照)、 60%(轻度胁迫)和50%(重度胁迫)3个水分处理。以水为对照,在黄瓜三叶一心期,叶面喷施LG-C(0.05 mg/L),每株喷施20 mL,连续喷施7天。然后立即取样分析植株的理化性质。【结果】与对照相比,轻度干旱胁迫下,喷施LG-C能够使黄瓜幼苗叶片中可溶性蛋白、 游离脯氨酸、 可溶性糖含量分别显著提高21.06%、 41.75%、 29.65%; 叶片中叶绿素a、 叶绿素b、 类胡萝卜素含量分别显著提高26.83%、 13.33%、 23.21%; 叶片中超氧化物歧化酶、 过氧化物酶、 过氧化氢酶活性分别显著提高10.06%、 19.34%、 33.08%; 叶片中电解质渗透率、 丙二醛含量、 自动氧化速率和组织失水率分别显著降低10.16%、 30.68%、 22.48%、 9.69%。重度干旱胁迫下,喷施LG-C能够使黄瓜幼苗叶片中可溶性蛋白、 游离脯氨酸、 可溶性糖含量分别显著提高19.35%、 37.05%、 25.23%; 叶绿素a、 叶绿素b、 类胡萝卜素含量分别显著提高28.17%、 20.00%、 28.42%; 超氧化物歧化酶、 过氧化物酶、 过氧化氢酶活性分别显著提高6.03%、 37.10%、 30.72%; 电解质渗透率、 丙二醛含量、 自动氧化速率和组织失水率分别显著降低10.15%、 47.10%、 16.97%、 8.85%。【结论】喷施LG-C可通过提高抗氧化酶活性、 渗透调节物质含量、 叶绿素含量和保水能力来增强黄瓜幼苗的抗旱能力。

Abstract:【Objectives】The chemical structure of laxogenin C(LG-C)is similar to the teasterone of brassinosteroids, which plays important roles in regulating plant growth. Both the compounds contain 3-aglycone-6-ketone functional groups of brassinosteroids(BRs), show bioactivity of plant hormone. LG-C is easily prepared in low cost, so more suitable to be used as plant growth regulator. The physiological effects of LG-C on cucumber seedlings under drought stress were studied in this paper to lay a foundation for the prospective practical use.【Methods】 Using cucumber seedlings as test materials, the effect of foliar spraying LG-C was studied using a pot experiment. Three percentages of field water capacity in growth substrates were set up as: 80%(CK), 60%(light stress)and 50%(heavy stress). LG-C(0.05 mg/L)was foliar sprayed when the seedling leaves were fully expanded. Each spray volume was 20 mL per seedling and the spray was conducted for 7 days successively, with spraying water as control for the two water stress treatments. The contents of physiological and bioactive compounds were measured immediately after the last spraying. 【Results】Compared with no LG-C treatment, under the light water stress, the contents of soluble protein, free proline, soluble sugar in the leaves of cucumber seedlings were increased by 21.06%, 41.75% and 29.65% respectively; the contents of chlorophyll a, chlorophyll b, carotenoid were increased by 26.83%, 13.33% and 23.21% respectively. The activities of superoxide dismutase, peroxidase and catalase were enhanced by 10.06%, 19.34% and 33.08% respectively. The electrolytic leakage, malondialdehyde content, autoxidation rate, water loss rate were decreased by 10.16%,30.68%,22.48% and 9.69%, respectively. Under heavy drought stress, the contents of soluble protein, free proline, soluble sugar in the leaves of cucumber seedlings were increased by 19.35%, 37.05% and 25.23% respectively. The contents of chlorophyll a, chlorophyll b, carotenoid were 28.17%, 20.00% and 28.42% higher respectively. The activities of superoxide dismutase, peroxidase and catalase were enhanced by 6.03%,37.10% and 30.72%, respectively. The electrolytic leakage, malondialdehyde content, autoxidation rate, water loss rate were decreased by 10.15%,47.10%,16.97% and 8.85%, respectively.【Conclusions】Exogenous LG-C may improve cucumber drought resistance by increasing the antioxidant activities, osmotic adjustment substances, chlorophyll content and water holding capacity.