Resistance of rice to ultraviolet-B radiation based on UVB-induced DNA lesions and their photorepairs

1.在大米生长期间DNA片段的变化： （1）我们发现大米可能是一个更可信赖的CPD指数在第二阶段、第三或第四叶正在开发，以及与低CPD照片epair的UVB敏感性相关的问题。（2）暗生长的老化大米不具有任何CPD照片完整性，并且CPD照片完整性的概念被视为由phytochrome/cryptochrome Photosystems控制。（3） It is evident that 2-3 CPDs/Mb. DNA总是在阳光辐射下保持水稻生长。2紫外线抵抗剂和敏感大米之间的CPD照片epair的交叉差异：我们先前建议有两个可能的帐户可用于紫外线敏感大米中CPD照片epair Deficiency（Norin 1）。一个是结构突变，它可能影响CPD-光子酶复合体的形成，或复杂体的分裂。另一个是为了使调节机制在光聚糖的定义中发生突变，可以降低光聚糖的水平。基于单光脉冲方法和温度依赖性，我们已经证明了在叶片中蛋白质含量的高紫外线敏感性下，在Norin1.3效应下，UVB辐射的结构突变可能会受到高紫外线敏感性的影响：我们先前建议，Rubisco比LHCII可能会受到补充紫外线辐射的影响。因此，我们研究了UVB辐射的合成和退化的影响（1），以及Rubisco和LHCII使用的LHCII作为示踪剂D115和LHCII的mRNA转录水平（氯铂中的核和rbcL编码）和LHCII （在核中的cab编码，在紫外线抵抗剂和敏感大米的叶子中的mRNA转录水平。我们发现，核编码基因的表达比UVB对氯铂的表达更受影响，而rbcL的表达比UVB对Cab的表达更受影响。

1 Changes in DNA lesions during growth in rice: (1) We found that rice could be more susceptible to CPD induction at the stage when the second, third or fourth leaves are developing, and UVB sensitivity correlates with low CPD photorepair. (2) Dark-grown etiolated rice does not have any CPD photorepair ability, and the induction of CPD photorepair was shown to be controlled by phytochrome/cryptochrome photosystems. (3) It was evident that 2-3 CPDs/Mb. DNA is always being kept in rice growing in solar radiation.2 Cultivar differences in CPD photorepair between UV-resistant and -sensitive rice : We previously suggested that two possibilities might account for CPD photorepair defiviency in UV-sensitive rice (Norin 1). One is due to a structural mutation, which could affect the formation of CPD-photolyase complex, or dissociation of the complex. The other is due to mutation of regulatory mechanisms for induction of photolyase, which could decrease the levels of photolyase. Based on the single light-pulse method and temperature dependence, we have proved that a structural mutation might be involved in high UV-sensitivity in Norin 1.3 Effect of UVB radiation on protein contents in leaves : We previously suggested that Rubisco rather than LHCII might be more influenced by supplemental UVB radiation during growth. Therefore, we studied the effects of UVB radiation (1) on the synthesis and degradation of Rubisco and LHCII using ィイD115ィエD1N as a tracer, and (2) on the mRNA transcript levels for Rubisco subunits (rbcS encoded in nuclear and rbcL encoded in chloroplast) and LHCII (cab encoded in nuclear, in leaves of UV-resistant and -sensitive rice. We found that the expression of nuclear encoded genes were more influenced than that of chloroplast by UVB, and that the expression of rbcL was more influenced than cab by UVB.