苯达松敏感致死(bentazon sensitive lethal,bsl)基因在杂交水稻(Oryza sativa L.)混播制种和杂交稻种纯度鉴定等方面具有广阔的应用前景.以水稻品种农林8号(N8)、W6154s和其对应的bsl突变体农林8号m(N8m)和8077s为材料,分析了苯达松处理对叶片中叶绿素(Chl)含量、丙二醛(MDA)含量、氧自由基含量、净光合速率(Pn)、叶绿素荧光参数等生理生化指标的影响及苯达松含量的变化,旨在揭示水稻苯达松抗性差异的生理机制.结果表明,苯达松处理使bsl突变体叶片光系统Ⅱ中还原性QA组分积累,光合电子传递受阻,光合能力丧失,氧自由基伤害积累,Chl降解、质膜氧化加剧,植株死亡.叶片中苯达松残留含量分析表明,较强的苯达松代谢能力是抗性品种免受苯达松伤害的主要原因.%Bentazon sensitive lethal (bsl) mutants can be applied in hybrid rice (Oryza sativa L.) breeding for improving seed production and quality. This study was to elucidate the physiological mechanism of bentazon tolerance in rice. Tolerant rice varie-ties (W6154s and Norin 8) as well as their corresponding mutants, sensitive to bentazon, were employed in this study. Plant net photosynthetic rate (Pn), chlorophyll fluorescence, and the level of superoxide radical ( O2- ) as well as the contents of chlorophyll (Chl) and malondialdehyde (MDA), were analyzed for both tolerant and sensitive rice plants treated with bentazon. After treat-ment, the two sensitive mutants showed a significant reduction in Pn at 0.5 h. A continuous decrease of Chl contents was found over the first 3 d whereas a significant increase of MDA contents was noticed on the 3rd day and thereafter. Analysis of chloro-phyll fluorescence revealed a bentazon-induced increase in the proportion of the reduced state of QA. In the early stage after bentazon treatment, wild types and their mutants showed no significant difference in the alteration of Pn and chlorophyll fluorescence. While these two parameters then increased progressively in both wild types and remained low in the mutants. A significant gen-eration of O2- was found over the 5 d period in the mutants. Both wild types and mutants contained the same level of bentazon after 2 h of treatment. Bentazon content dropped to barely detectable amount in the wild type varieties at 1 d. However, the mu-tants retained a substantial amount of the herbicide after 5 d. It is proposed that the herbicide might inhibit rice photophythesis and accumulation of oxidative stress with the treatment of bentazon in both lethal mutants. The damaging effect on PS Ⅱ system can be significantly alleviated in the wild type varieties due to a higher rate of catabolism of the herbicide.
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