低温锻炼对冷胁迫下棉苗叶片细胞超微结构的影响

【目的】棉花苗期易受低温伤害,适宜的低温锻炼可以提高棉苗耐冷性。通过观察晋棉49、科能0518棉苗真叶细胞超微结构,分析12℃低温锻炼对4℃冷胁迫适应性的影响。【方法】将上述2个品种脱绒后的棉种浸泡适当时间,于28℃/12 h光照条件下培养至长出至少2片真叶后,均分为2组:一组作为对照(未低温锻炼),另一组于12℃/12 h光照条件下低温锻炼5 d,然后2组均于4℃/12 h光照条件下冷胁迫5 d,在电镜下观察、比较、分析其真叶细胞超微结构的变化。【结果】经过12℃锻炼5 d后在4℃冷胁迫过程中,相比未经锻炼处理,晋棉49叶绿体结构更完整,且积累淀粉粒,细胞之中出现高电子吸收物质;科能0518叶绿体结构也更完整,积累更多的淀粉粒,核膜完整,线粒体聚集排列、结构完整,内质网呈管状和泡状,细胞内同样出现大量高电子吸收物质。【结论】经过12℃低温锻炼,棉苗可以通过维持叶绿体的完整性,积累淀粉粒,在细胞质中积累高电子吸收物质来适应4℃冷胁迫。

Effects of Cold Acclimation on Chilling Tolerance and Leaf Ultrastructure in Cotton Seedlings

[Objective] Cotton seedlings are predisposed to chilling injury,and proper low-temperature pretreatment may improve the cold tolerance.The aim of this study is to analyze the effects of 12 ℃ cold acclimation to 4 ℃ cold tolerance by observing the leaf cell ultrustructure of Jinmian 49 and Keneng 0518 cotton seedlings.[Method] Cotton seeds of the two varieties were delinted and soaked for appropriate time,then cultured at 28 ℃/12 h lighting condition.At stage of euphylla,half of the seedlings were placed at 12 ℃/12 h lighting acclimation for 5 days,leaving the others as control (non-cold acclimation);Then all placed at 4 ℃/12 h lighting treatment for 5 days,and leaf cell ultrastructure were observed and compared.[Result] In the 4 ℃ cold tolerance process,Jinmian 49 and Keneng 0518 with cold acclimation at 12 ℃ for 5 days kept better chloroplast,accumulated starch grain and high electron absorbing material;Keneng 0518 also kept integrated nucleus membrane,congregated arrangement of mitochondrion,tubular or bubbly endoplasmic reticulum.[Conclusion] These results indicated that cotton seedlings could adapt to 4 ℃ cold tolerance through better chloroplast,accumulating starch grain and high electron absorbing material after 12 ℃ cold acclimation.