PEG6000胁迫对大麦幼苗叶片表皮蜡质组分及其透性的影响

为了探究干旱胁迫条件下大麦幼苗叶片表皮蜡质组分和含量与品种保水能力的关系,采用PEG6000模拟干旱胁迫,研究干旱胁迫对大麦幼苗叶片表皮蜡质组分、含量及叶片表皮透性的影响。结果发现,胁迫6d后,大麦幼苗叶片的表皮蜡质总量和各组分含量均呈极显著增加。气相色谱-质谱联用分析表明,大麦幼苗叶片表皮蜡质的主要组分为醇类、酸类、醛类、酮类、烷烃类、酚类、酯类及一些未知物质,其中含量较多的组分为醇类和酸类,其次为醛类,且这三种蜡质组成成分的增加量也相对较多,说明在大麦幼苗叶片蜡质组分中,醇类、酸类和醛类物质的合成是大麦幼苗叶片表皮蜡质对干旱胁迫响应的关键。表皮蜡质的合成受植物体内水分状况的调控,尤其是蜡质组分中的醛类、酮类、醇类和酯类物质的合成受胁迫影响较大,是构成表皮蜡质应激反应的主要成分。蜡质含量高的品种的失水率相对较低,在逆境胁迫下可以保持相对较高的含水量,但除品种垦啤6号外,其他品种的叶绿素浸出率均增加,这可能是由不完整的表皮或蜡质组分中大量的醇类物质造成的。

Responses of Epicuticular Wax Components in Barley Seedling Leaves to PEG6000 Stress and Its Impacts on Epidermal Permeability

In order to investegate the relationship between epicuticular wax components and contens of barley seedling leaves and water retaining capacity of barley cultivars under drought stress,the responses of epicuticular wax components and contens of barley seedling leaves to drought stress and its impacts on epidermal permeability were studied.In this paper,PEG6000 was used to simulate the drought stress and found that the total contents of epicuticular wax and each component contents in barley seedling leaves were increased significantly after stressed 6 d with PEG6000.GC MS analysis indicates that the major components of barley seedling leaves wax were alcohols,acids,aldehydes,ketones,alkanes,phenols,esters,and some unknown substances.Among them,the content of alcohols and acids accounted for most,followed by aldehydes,and the increasing amount of the three wax composition was also relatively more,so it appears that the synthesis of alcohols,acids and aldehydes are keys to PEG6000 stress response.The study found that ,the synthesis of epicuticular wax was regulated by the water status of plants,especially the wax components of aldehydes,ketones,alcohols and esters.The result showed that aldehydes,ketones,alcohols and esters are the main components of epicuticular wax in the plant stress response.Studies presented here demonstrate that varieties which with high wax content had a lower water loss rate and a higher relative water content under PEG6000 treatment,whereas,the chlorophyll leaching of other cultivars were higher than that of the control samples except the variety of KP.We suspect that it might be caused by incomplete epidermal layers or large numbers of alcohols in wax components.