【作者】 刘强；

【导师】 郑绍建；

【作者基本信息】 浙江大学 ， 植物营养学， 2006， 博士

【摘要】 铝毒是制约酸性土壤上作物生产的主要因素之一。铝诱导有机酸分泌及细胞壁的作用是近年来植物抗铝机理的研究热点。本文在筛选不同小黑麦品种铝敏感性的基础上，研究了根尖细胞细胞壁中的果胶、阳离子交换量(CEC)及铝诱导的有机酸分泌在抗铝性中的作用。此外，我们深入研究了铝胁迫诱导的根尖氧化胁迫、细胞壁成分改变与铝毒之间的关系，以阐明铝毒害的原初作用位点。为了探明细胞壁及其与铝诱导分泌的有机酸的相互作用，我们以离体细胞壁为材料，采用动力学的手段研究了抗性小麦Atlas 66及抗铝性不同的近等位基因小麦ET8(抗性)和ES8(敏感)不同根段(0-1、1-2、2-3 cm)细胞壁对铝的吸附与解吸特性和苹果酸分泌在保护细胞壁铝吸持位点中的作用。结果概述如下： 1．小黑麦抗铝机理 所选用的10个小黑麦品种在抗铝性上存在着显著基因型差异，但它们的根尖果胶含量、CEC与抗铝性之间不存在显著相关性，说明根尖细胞壁的带电性并不是影响小黑麦抗铝性的主要因素。同时，我们发现小黑麦根系在铝胁迫下可同时诱导分泌苹果酸和柠檬酸，且分泌的有机酸量与抗铝性呈显著正相关，与根尖铝含量呈显著负相关，表明由有机酸分泌而形成的铝排斥作用是小黑麦的主要抗铝机制。对抗铝性差异最大的两个小黑麦品种(ZC 237和OH 1621)的深入研究表明，铝诱导的有机酸分泌存在一个明显的滞后期(3小时)，分泌量随外部铝处理浓度的提高而增加，且抗铝品种的分泌量远高于敏感品种。此外，铝诱导的有机酸分泌在低温条件下(4℃)基本停止，且被阴离子通道抑制剂(Phenylglyoxal和Niflumic acid)所抑制，说明铝诱导的有机酸分泌受代谢调节，且是通过质膜上的阴离子通道实现的。 2．铝对小黑麦根尖毒害的原初作用位点 为了探讨铝毒引起的根伸长快速抑制的原初作用位点，我们以抗铝性差异显更多还原

【Abstract】 Aluminum (Al) toxicity is one of the major factors limiting crop poduction in acid soils. In recent years, Al-induced secretion of organic acids and the role of cell wall have received strong support in Al resistance mechanisms. In the present study, the cell wall pectin content, CEC of root apices and Al-induced secretion of organic acid anions from roots of 10 triticale cultivars differing in Al resistance were examined. Besides, the effects of Al on root elongation, plasma membrane lipid peroxidation, and changes of cell-wall compostition in two triticale cultivars with the largest difference in Al resistance were investigated to elucidate the primary target sites of Al toxicity. In order to explore the role of cell wall and its interaction with Al-induced organic acids secretion, root cell walls were extracted from Al-resistant wheat cultivar Atlas 66 and from different root segments (0-1, 1-2, 2-3 cm) of a pair of near-isogenic wheat lines, ET8 (Al-resistant) and ES8 (Al-sensitive), to investigate their kinetics of Al adsorption and desorption, and the role of malate in protecting cell walls from binding Al. The results were summarized as followings:1. The mechanism of aluminum resistance in triticaleTriticale (X Triticosecale Wittmack) shows a high degree of aluminum resistance, but variation in Al resistance between cultivars does exist. There was no significant correlation among root apical pectin content, CEC and Al resistance, indicating the electrification of cell wall was not the primary factor determining Al resistance in triticale. Triticale roots secreted both malate and citrate in response to Al stress. The amount of organic acid anions secreted was correlated positively to the relative root elongation and negatively to the Al content in root apices under Al stress. The comparative studies with an Al-resistant cultivar (ZC 237) and an Al-sensitive cultivar (OH 1621) showed that a marked lag phase (3 h) in the secretion of organic acid更多还原