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干旱区地理 ›› 2016, Vol. 39 ›› Issue (6): 1291-1297.

• 生物与土壤 • 上一篇    下一篇

外源水杨酸对低温胁迫下黄瓜幼苗抗氧化酶活性和基因表达的影响

徐晓昀, 郁继华, 颉建明, 王银   

  1. 甘肃农业大学园艺学院, 甘肃 兰州 730070
  • 收稿日期:2016-06-11 修回日期:2016-08-27
  • 通讯作者: 郁继华.Email:yujihua@gsau.edu.cn
  • 作者简介:徐晓昀(1981-),男,讲师,在读博士,研究方向为园艺作物逆境生理.Email:xuxy@gsau.edu.cn
  • 基金资助:

    甘肃省自然科学基金项目(145RJYA244);公益性行业(农业)科研专项经费(201203001)

Effects of exogenous salicylic acid on antioxidant enzyme activities and gene expression in cucumber seedlings under low temperature stress

XU Xiao-yun, YU Ji-hua, XIE Jian-min, WANG Yin   

  1. College of Horticulture, Gansu Agricultural University, Lanzhou 730070, Gansu, China
  • Received:2016-06-11 Revised:2016-08-27

摘要: 为了探讨外源水杨酸(SA)对低温胁迫下黄瓜幼苗的生长调节作用,以‘优博1-5’黄瓜为试材,采用叶面喷施外源SA的方法,研究其对低温胁迫下黄瓜幼苗生长量、光合特性、抗氧化酶活性的影响,并采用Real-time PCR测定抗氧化酶基因表达水平的变化。结果表明:低温胁迫下黄瓜幼苗生长量下降,净光合速率(Pn)、光系统II最大光化学效率(Fv/Fm)、抗氧活酶活性及其mRNA表达显著降低,但SA预处理后黄瓜幼苗的生长量、PnFv/Fm降低幅度明显较小,并且诱导了抗氧活酶活性及其基因表达量的升高。由此可见,SA能够在转录水平调控抗氧化酶活性的升高,进而缓解低温对黄瓜幼苗光合作用的影响,增强其对低温的适应性。

关键词: 水杨酸, 黄瓜, 抗氧化酶, 基因表达, 低温

Abstract: Low temperature is a major limiting factor for the productivity of many thermophilic plants such as cucumber and tomato, they may experience a physiological dysfunction called chilling injury when exposed to nonfreezing temperatures below 12℃ for more than the critical period. However, the development of chilling injury symptoms may be mainly due to the production of activated oxygen species(AOS) (superoxide radicals, singlet oxygen, hydrogen peroxide and hydroxyl radical) that can cause damage to proteins, nucleic acids and cell membranes. Salicylic acid(SA), which is an ubiquitous plant phenolic, has been reported to induce defense responses and increase chilling tolerance in plants. Although some studies found that SA can increase chilling tolerance of cucumber(Cucumis sativa L.) seedlings by promoting the activities of antioxidant enzyme, its molecular mechanism still remains unclearly. In this study, the stress condition of low temperature(day/night 10/5℃, photo flux density 80 μmol·m-2·s-1) was stimulated in a light growth chamber, and cucumber ‘Youbo1-5’ was used as the material. Cucumber seedlings were sprayed with deionized water or 1 mmol·L-1 SA once a day at the 30-day ages. Forty eight hours after treatment, plants were exposed to low temperature stress for 4 days, then were allowed to grow under normal conditions(day/night 25/18℃, photo flux density 300 μmol·m-2·s-1) for 2 days. The effects of SA spraying on growth, photosynthetic characteristics and antioxidant enzyme activities were investigated, and the gene expression of antioxidant enzyme was determined by quantitative real-time PCR analysis. The most evident effect of low temperature stress was the marked reduction in plant growth, chlorophyll content, and net photosynthetic rate. Four days after treatment, low temperature stress reduced the specific leaf weight, SPAD value, photosynthetic rate(Pn) and maximal photochemical efficiency of PSII(Fv/Fm) by 18.2%, 30.37%, 64.99% and 4.18% over their respective controls, respectively. However, seedlings pretreated with 1 mmol·L-1 SA had higher values of above parameters, compared to the water sprayed plant. When plants were treated 1d under low temperature, the activities of superoxide dismutase(SOD), peroxidase(POD), catalase (CAT) decreased by 11.56%, 23.88% and 29.29% over the control, respectively, and increased more or less after 4 days. In contrast, the stressed seedlings pretreated with SA increased the activities of SOD, POD and CAT over the controls during low temperature stresses and recovers stage. The quantitative real-time RT-PCR analysis indicated that the expression of SOD, POD and CAT genes could be induced by SA and their relative expression maintained high values under low temperature stress. We considered that SA(1 mmol·L-1) enhanced low temperature tolerance in cucumber seedlings may due to the induction of SOD, POD and CAT transcription factor and activations of antioxidative capacity. The study provides theoretical basis to elucidate the molecular mechanism of SA alleviating low temperature stress on cucumber seedlings.

Key words: salicylic acid, cucumber, antioxidant enzyme, gene expression, low temperature

中图分类号: 

  • Q945.78