低温胁迫对狗牙根激素和碳水化合物代谢的影响

以杂交狗牙根品种天堂419,天堂328,老鹰草,运动百慕大和普通狗牙根品种保定狗牙根为试验材料,分析了人工模拟昼夜温度为适温(30℃/25℃)、亚适温(18℃/10℃)、冷害(8℃/4℃)和冻害(4℃/-4℃)等4种梯度降温冷驯化条件下,低温胁迫对狗牙根叶片细胞膜稳定性、叶绿素含量、内源激素(ABA、IAA,GA₃和tZR)以及可溶性糖、淀粉、果聚糖、总非结构性糖等碳水化合物代谢的影响。结果表明:随着温度的降低,狗牙根叶片的电导率显著升高,叶绿素含量下降,内源激素ABA含量升高,而IAA,GA₃和tZR含量均下降;碳水化合物中可溶性糖、果糖和总非结构性糖含量在5个品种中均呈不同程度的升高,但不同品种在冷驯化过程中不同温度处理下其变化差异较大,如天堂328、老鹰草和运动百慕大的淀粉含量下降;天堂419的淀粉含量变化不大,而保定狗牙根的淀粉含量则呈上升趋势。综合分析各生理指标的变化,5个狗牙根品种的抗寒能力强弱为:保定狗牙根最弱,而天堂419,老鹰草、天堂328和运动百慕大耐寒能力依次较强。低温胁迫下积累或维持较高的内源激素ABA、GA₃、IAA、tZR和碳水化合物可溶性糖和果聚糖可能是耐寒性较强的主要原因,这些代谢物的积累或维持有助于狗牙根细胞内渗透平衡和细胞膜稳定性的维持,延缓叶片的枯黄衰老和诱导抗性相关基因或蛋白的表达从而提高了狗牙根品种的抗寒能力。

Effect of low temperature on phytohormones and carbohydrates metabolism in Ber-muda grass

To investigate the effects of modulated cold acclimation on the leaf membrane stability,chlorophyll content,endogenous hormones (ABA,IAA,GA3 ,tZR),and carbohydrate (soluble sugars,starch,fructan, total nonstructural carbohydrates)metabolism,five Bermuda grass cultivars,Tifway,Tifgreen,Tifsport, Tifeagle and Baoding were selected and treated under a range of temperatures:optimum (30℃/25℃),subopti-mum (18℃/12℃),chilling (8℃/4℃)and freezing (4℃/-4℃)in growth chambers.The results demonstra-ted that leaf electrolyte leakage,abscisic acid (ABA)content and carbohydrates (soluble sugars,starch,fruc-tan,total nonstructural carbohydrates )increased while chlorophyll content,endogenous hormones auxin (IAA),gibberellin (GA3 )and cytokinin (tZR)content decreased with low temperature stress,but the changesvaried with cultivar.Tifeagle,Tifsport and Tifgreen were ranked highest,Tifway was ranked intermediate while Baoding ranked lowest.Accumulating or maintaining relatively higher levels of phytohormones and car-bohydrates,associated with cellular osmotic homeostasis and membrane stability,delayed leaf senescence. Cold resistance genes or protein induction may contribute to the higher cold tolerance in Bermuda grass under low temperature.