外源水杨酸对低温胁迫下海滨雀稗抗寒生理特征的影响

为探讨水杨酸(SA)对海滨雀稗耐寒性的影响,以海滨雀稗“白金”品种为材料,分析了外源水杨酸(1 mmol·L^-1)预处理对适温(30 ℃/25 ℃,昼/夜),冷害(8 ℃/4 ℃)和冻害(2 ℃/-2 ℃)3种温度处理下海滨雀稗生长速率和草坪质量、叶片电导率(EL)和丙二醛(MDA)含量、抗氧化酶超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性、脂肪酸含量及脂肪酸不饱和指数的影响。结果表明,在冷害和冻害下,草坪质量下降,叶片EL增大,MDA含量升高,叶片SOD、POD和CAT活性升高;而外源SA预处理显著缓解低温对海滨雀稗草坪质量的伤害,降低叶片EL和MDA含量,提高SOD、POD和CAT活性。低温下叶片不饱和脂肪酸含量升高,饱和脂肪酸含量下降,而外源SA预处理将进一步显著提高不饱和脂肪酸的含量和脂肪酸不饱和指数。因此,外源SA预处理显著提高冷害和冻害胁迫下海滨雀稗叶片的不饱和脂肪酸含量和不饱和指数,从而维持低温胁迫下细胞膜的稳定性,增强抗氧化能力,缓解低温对植株的伤害而提高耐寒能力。

Effect of exogenous salicylic acid on the antioxidant enzyme activities and fatty acid profiles in seashore paspalum under low temperature stress

This research investigated the effect of exogenous salicylic acid(SA) on the cold tolerance of seashore paspalum(Paspalum vaginatum), cultivar "Platinum". A pre-treatment of 1 mmol·L^-1 SA was applied to plants in pots and after 5 days, turf quality, leaf electrolyte leakage(EL), malondialdehyde(MDA) content, antioxidant enzyme activity(superoxide dismutase, SOD;peroxidase, POD;catalase, CAT), fatty acid content and an index of unsaturated fatty acid occurrence, were determined. There were three temperature treatments: optimal temperature(30 ℃/25 ℃, day/night), chilling(8 ℃/4 ℃) and freezing(2 ℃/-2 ℃), and four replicates for SA treated and untreated pots/swards. The results showed that turf quality was adversely affected, and leaf electrolyte leakage(EL), MDA content and SOD, POD and CAT activity were increased under the chilling and freezing temperature treatments. Pre-treatment with exogenous SA significantly alleviated the detrimental effect of chilling and freezing stress on the plant growth, turf quality, EL, MDA content and antioxidant enzyme activity. The saturated fatty acid content was increased, and unsaturated fatty acid content and the index of unsaturated fatty acid occurrence were decreased under chilling and freezing temperature treatments;while pre-treatment with exogenous SA diminished these chilling and freezing effects, compared to those seen in pots not receiving SA. These results indicate that one factor in the SA-enhanced cold tolerance of seashore paspalum is the maintenance and/or increase in unsaturated fatty acid content and the index of unsaturated fatty acid occurrence, which would in turn enhance membrane stability and contribute to the observed enhancement of chilling and freezing tolerance.