干旱胁迫对不同耐旱性大麦品种叶片超微结构的影响

选用耐旱性不同的3个大麦(Hordeum sativum)品种作为研究对象, 分析干旱胁迫对其叶肉细胞叶绿体、线粒体和细胞核超微结构的影响。结果表明, 3个大麦品种在非胁迫条件下其超微结构无明显差异。遭受干旱胁迫后, 不耐旱大麦品种Moroc9-75叶片细胞核中染色质的凝聚程度高, 叶绿体变形, 外被膜出现较大程度的波浪状和膨胀, 同时基粒出现弯曲、膨胀、排列混乱的现象; 线粒体外形及膜受到破坏、内部嵴部分消失等。耐旱大麦品种HS41-1叶片细胞中染色质虽出现凝聚, 但凝聚程度低; 其叶绿体及线粒体与非胁迫条件下基本相似, 多数未见明显损伤。耐旱中等的大麦品种Martin叶片超微结构的变化则介于二者之间。因此, 干旱胁迫下叶绿体外形、基粒和基质类囊体膜结构的完整性与基粒的排列次序、染色质的凝聚度和线粒体膜及嵴的完整性与大麦的耐旱性相关, 这些特性可作为评价大麦耐旱性强弱的形态结构指标。

Impact of Drought Stress on the Ultrastructure of Leaf Cells in Three Barley Genotypes Differing in Level of Drought Tolerance

We examined 3 barley genotypes differing in level of drought tolerance in terms of structural differences at the subcellular level. The subcellular structure did not differ among the 3 genotypes under non-stressed conditions, but nuclei, chloroplasts and mitochondria of leaf cells of all 3 genotypes showed ultra-structural changes after drought stress treatment. In the drought-sensitive genotype Moroc9-75, drought stress caused a high degree of chromatin condensation, altered chloroplast conformation with the waving/swelling of the outer membrane of the chloroplast envelope, and disrupted thylakoids that showed conformational and configurational alterations. In addition, the structure and membrane of the mitochondria was disrupted, and cristae partially disappeared. In the drought-tolerant genotype HS41-1, water shortage caused lighter chromatin condensation than in Moroc9-75, and after drought stress, most chloroplasts and mitochondria in leaf cells showed no significant changes in conformation or configuration. Martin possessed moderate tolerance to drought, and its response to water deficit was between that for HS41-1 and Moroc9-75. Therefore, drought tolerance in barley is related to chloroplast shape, the integrity of grana and stroma thylakoids in chloroplasts and their regular arrangements, the degree of chromatin condensation, and the integrity of mitochondria and cristae. These ultrastructural traits could be used as structural indexes for evaluating drought tolerance in barley.