【作者】 肖美秀；

【导师】 林文雄；

【作者基本信息】 福建农林大学 ， 生物化学与分子生物学， 2005， 硕士

【摘要】 采用水培营养液加镉法,对72个水稻品种（系）进行不同抗性水稻种质资源的筛选。试验结果表明,供试的72个水稻基因型的耐镉胁迫能力存在极显著差异,依据0.2mg/LCd处理下的Cd耐性指数可将72个基因行聚成Cd敏感基因型、较敏感基因型、耐-Cd基因型、较耐基因型。其中以Lemont、IR98-22、兰贝利、F₆-143-1、Dular、玉米粳5号、R669等耐性最强,F₆-138-1等对镉胁迫最敏感。 在水培耐Cd基因型筛选实验的基础上,以Cd耐性不同的基因型材料（Lemont和F₆-138-1）,研究了不同生长发育时期Cd在水稻各器官的动态变化规律及Cd胁迫下水稻苗期功能叶的生理生化特性。 结果表明,水稻各器官Cd含量随Cd处理水平和生育进程而增加,且吸收的Cd主要积累在根系,Cd在水稻各部位中的分布规律为:根>>茎>鞘>叶>稻米。在8mg/Kg Cd处理下,品种F₆-138-1稻米中Cd含量超标,而品种Lemont稻米中未检出,进一步验证Cd胁迫下Lemont的耐性比F₆-138-1高,这与前期的筛选结果一致。 通过Cd胁迫对水稻叶绿素含量的影响的研究,结果表明,0.8mg/LCd处理显著降低叶绿素含量,与叶绿素b相比,叶绿素a对Cd胁迫更敏感。基因型间差异显著,Cd敏感基因型F₆-138-1受抑制更严重,耐Cd基因型Lemont表现出相对较强的抗性。 通过Cd胁迫对水稻抗氧化酶系统影响的研究,结果表明,0.8mg/LCd处理7～14d显著增加SOD、POD和CAT酶活性,并导致MDA含量增加,上述效应随处理浓度的提高和处理时间的延长而加重,0.8mg/LCd处理21d后。虽然SOD活性显著下降,但POD活性仍然继续上升。Cd胁迫对细胞保护酶活性的影响存在品种间差异。高浓度Cd处理（0.8mg/L）7～14d Cd敏感基因型F₆-138-1 SOD、POD和CAT活性增幅更低,21d SOD活性降幅更高,MDA含量积累更多,受抑制更严重,耐Cd品种Lemont表现出相对的较强的抗性。 通过Cd胁迫对水稻抗氧化物质含量影响的研究,结果表明,Cd胁迫显著降低Cd敏感基因型F₆-138-1的总酚和类黄酮含量,而显著增加耐Cd基因型Lemont的总酚和类黄酮含量,这种表现出的品种间差异部分也可以说明它们在耐Cd性的差异。 最后本文还就有待于深入研究的问题作了进一步的讨论。更多还原

【Abstract】 72 rice cultivars with different Cd tolerance were screened by adding Cd in the hydroponic culture nutrition. The results indicated a significant genotypic variation of Cd tolerance in the tested 72 cultivars. The cluster analysis of tolerance indices, including shoot height and its dry weight, root length and its weight of rice plants exposed to 0.2mg/L Cd level , showed that 72 rice genotypes may be grouped into four clusters, i.e. Cd sensitive genotype, relatively sensitive genotype, tolerant genotype and relatively tolerant genotype. Of 72 rice cultivars, Lemont, 1R98-22, Lanbeili, F6-143-1, Dular, Yumijing5, R669. and so on, were the most tolerant, F6-138-1 was the most sensitive.The Cd contents of various plant parts at different Cd levels and different time and the physio-biochemical characteristics of functional leaves were studied in two rice cultivars（F₆-138-1 and Lemont） with different Cd-tolerance according to the previous screening experiment. The results were summarized as follows:It was showed that Cadmium accumulation in root and shoot of two rice cultivars increased with increasing external Cd levels and the time of Cd exposure. The pattern of Cd accumulation and partitioning is: root?straw>sheath>leave>kernel. The higher Cd concentration in kernel of F₆-138-1 compared to Lemont could be believed that it was more sensitive to Cd ToxicityThe genotypic differences in the effect of Cd on the content of chlorophyll was studied. It was show that 0.8mg/L Cd stress caused a sharp decline in chlorophyll content.and chlorophyll a showed more sensitive to Cd toxicity than chlorophyll b.There was a highly significant difference in the reduction of chlorophyll content in 2 rice concerned.A hydroponic experiment was carried out to study genotypic difference in effect of three Cd levels on activities of antioxidant enzymes in functional leaves of rice seedlings. A highly significant increase in MDA content, and a stimulation of SOD, POD and CAT activities were recorded in the plants subjected to 0.8mg/L Cd, and the effect increased with both Cd concentration and the time of exposure.during 7¹4d. Although the activity of SOD reduced significant at 21d, but that of POD increased. There was the significant genotypic difference in activities of antioxidant enzymes.The genotypic difference in potential antioxidant capacity between更多还原