外源独脚金内酯对陆地棉幼苗低温胁迫的缓解作用

Alleviation Effects of Exogenous Strigolactone on Cold Stress in Upland Cotton Seedlings

独脚金内酯(SLs)是类胡萝卜素衍生的新型植物激素,影响植物的生长发育,但目前独脚金内酯是否能提高棉花的耐寒性尚不清楚。本研究揭示了独脚金内酯缓解棉花低温胁迫的机制,低温胁迫(4℃)显著抑制了棉花幼苗的生长,外源SLs处理可显著缓解低温胁迫对棉花幼苗生长的影响。独脚金内酯人工合成类似物(rac-GR24)处理显著缓解低温胁迫引起的氧化应激损伤,从而保护细胞结构和功能,提高超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)、抗坏血酸过氧化物酶(ascorbate peroxidase,APX)的活性,增加可溶性糖含量和可溶性蛋白含量,提高叶绿素含量,显著缓解光合效率的下降,有效缓解叶绿素荧光参数和光合气体交换参数的变化。为了进一步阐明SLs缓解低温胁迫的机制,在低温处理0和6 h时进行转录组分析,结果发现常温下(0 h)差异表达基因(DEGs)主要参与类黄酮代谢和谷胱甘肽代谢,大部分基因上调表达,而低温处理6 h时主要富集到光合作用和磷酸戊糖代谢和其他糖的代谢,这与生理生化实验结果一致。综上所述,外源独脚金内酯处理在低温胁迫下可能通过抗氧化活性、光合效率和糖代谢提高来缓解陆地棉幼苗的低温胁迫。这些结果为陆地棉耐低温品种育种提供了理论依据。

Strigolactones(SLs)is a phytohormones derived from carotenoids,that affects the growth and development of plants.But whether or not the strigolactone can improve cold tolerance in cotton remains unclear.In this study,the roles of SLs in alleviating cold stress in cotton were studied,the results showed that cold stress(4℃)significantly inhibits the growth of cotton seedlings,and the application of exogenous synthesized strigolactone analogue(GR24)significantly alleviate cold stress of cotton seedlings.GR24 application decreased oxidative stress,protect cell structure and function,improved the activity of the superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and ascorbate peroxidase(APX),it also increased the content of soluble sugar and soluble protein content,alleviate the decrease of chlorophyll contents and effectively relieve the change of chlorophyll fluorescence parameters and photosynthetic gas exchange parameters.In order to further elucidate the mechanism of strigolactone for alleviating the cold stress.Transcriptome analysis was performed at 0 and 6 hours under cold stress.The results showed that the differentially expressed genes(DEGs)were mainly involved in the pathway of flavonoids metabolism and glutathione metabolism,and most of the genes were up regulated at 0 hour.DEGs were mainly participating in photosynthesis and sugar metabolic process including pentose phosphate pathway at 6 hour under cold stress,these were consistent with the results of previous physiological and biochemical experiment.In conclusion,the application of exogenous GR24 may alleviate the cold stress of cotton seedlings by improving the antioxidant activity,increasing photosynthetic efficiency and regulating sugar metabolism.These results provide theoretical basis for cotton breeding to cold stress.