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为探究外源水杨酸(SA)对低温下黄瓜幼苗脂肪酸组成的影响,采用根系施用SA的方法,测定了正常生长温度和低温(8℃)条件下SA处理对黄瓜幼苗叶片中脂肪酸含量、组分,以及脂肪酸去饱和酶基因(CsFAD)表达水平的影响。结果表明:根系施用SA能降低叶片中因低温引起的丙二醛积累和相对电解质渗漏,维持细胞膜稳定性;低温引起叶片中总脂肪酸含量减少,C_(18:3)等多不饱和脂肪酸相对含量降低,C_(18:0)、C_(18:1)等脂肪酸比例升高,脂肪酸双键指数降低;根系施用SA后,叶片中总脂肪酸含量、脂肪酸不饱和度及双键指数均得以恢复;低温诱导叶片中CsFAD的表达,低温下外源施用SA可进一步促进CsFAB2.1、CsFAB2.2、CsFAD2.1、Cs FAD6和CsFAD7等的表达。总之,SA可以诱导黄瓜幼苗中CsFAD的表达,维持细胞膜脂肪酸不饱和度,提高细胞膜稳定性,诱导耐低温性。
In order to explore the effect of exogenous salicylic acid (SA) on the fatty acid composition of cucumber seedlings under low temperature, the effect of SA on the growth of cucumber seedling leaves and the content of fatty acids in normal and low temperature (8 ℃) Components, and fatty acid desaturase gene (CsFAD) expression levels. The results showed that root application of SA could reduce the malondialdehyde (MDA) accumulation and relative electrolyte leakage caused by low temperature and maintain the stability of cell membrane. Low temperature caused the decrease of total fatty acid content in leaves, and the relative content of polyunsaturated fatty acids such as C_ (18: 3) The content of fatty acids in C_ (18: 0), C_ (18: 1) increased and the double bond index of fatty acid decreased. After SA application, the total fatty acid content, fatty acid unsaturation and double bond index of leaves were restored The expression of CsFAD in leaves was induced by low temperature, and the expression of CsFAB2.1, CsFAB2.2, CsFAD2.1, Cs FAD6 and CsFAD7 could be further enhanced by exogenous application of SA at low temperature. In conclusion, SA can induce the expression of CsFAD in cucumber seedlings, maintain the fatty acid unsaturation of cell membrane, improve the stability of cell membrane and induce the hypothermia resistance.