干旱胁迫下紫花苜蓿表皮蜡质的生理生态学研究

项目名称： 干旱胁迫下紫花苜蓿表皮蜡质的生理生态学研究

项目编号： No.30800802

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 轻工业、手工业

项目作者： 郭彦军

作者单位： 西南大学

项目金额： 20万元

中文摘要： 表皮蜡质层是覆盖在植物地上部分最表层的保护层，是植物自我防护的最后一道屏障。在过去3年时间，我们研究小组系统研究了紫花苜蓿叶表皮蜡质特征及其对环境胁迫的响应，建立了叶表皮蜡质分析平台。紫花苜蓿叶表皮存在致密的蜡质层，蜡质晶体结构成片状，多数垂直于叶片呈不规则排列，无特殊的晶格方向。叶表皮蜡质主要有烷、醇、酯等组成，其中一级醇占41.7%-54.2%，烷类占13.2%-26.9%，酯类17.5%-28.9%，醛类占1.4%-3.4%，未知成分占4.5%-18.4%。紫花苜蓿叶表皮蜡质含量在品种之间存在显著差异，其中敖汉、皇后和德福品种表皮蜡质含量显著高于大叶、中苜和三得利。单独土壤水分胁迫后，一级醇含量显著下降，烷类含量显著增加，但蜡质总量和晶体结构无显著变化。增强紫外线强度，蜡质片状晶体结构发生熔融，扩大了对叶表面积的覆盖，对紫外线辐射有直接物理防御作用，这种作用可推迟或部分替代通过生理代谢途径对紫外线的防御。低空气湿度胁迫下晶体结构也发生熔融，直接降低水分从叶表散失。提高空气温度对叶表皮蜡质晶体结构和组分无显著影响。研究计划全部完成，并达到预期目标。

中文关键词： 紫花苜蓿；表皮蜡质；抗旱性；生理生态

英文摘要： Leaf cuticular waxes cover plant surfaces and form a protective barrier between a plant and its environment.During the past three years, our research group analyzed the cuticular wax characteristics on leaves of Medicago sativa and their responses to environmental stress, and set up research platform for wax analysis. Our results showed that the alfalfa leaf surface was covered by thick wax platelets without specific orientations, which were constituted of alkanes (13.2%–6.9%), primary alcohols (41.7%-54.2%), terpens (17.5%–8.9%), aldehydes (1.4%-3.4%, and unknown constituents (4.5%–8.4%). The total wax contents in leaves of cultivar Aohan, Queen and Defi were significantly higher than those of cultivar Daye, Sanditi and Zhongmu. Under the condition of soil water deficit, the contents of primary alcohols decreased, alkanes increased, total wax content and crystal structure changed insignificantly. Under the conditions of enhanced ultraviolet radiation (UVR), the platelet wax crystalloid melted, increased covering areas and had direct defense mechanism to UVR, which partly might delay or replace the defense mechanisms from secondary metabolic compound such as ultraviolet absorbing compounds. The wax crystalloid structure melted and dispersed over leaf surface under low air humidity conditions, resulting in a significant reduction of water loss due to decreased transpiration rate. Under the conditions of enhanced air temperature, total wax content and crystalloid structure changed insignificantly. All research work was completed as planned and obtained most of the aims.

英文关键词： Alfalfa; cuticular wax; drought resistance; physiological and ecological