Difperent sensitiorty UVB radiation of rice cultioors based on UVB-caused CPDs Frequencies

前期研究发现，UVB辐射降低了水稻分蘖数和生物量，降低了叶片中可溶性蛋白质、Rubisco等的含量。籼稻、爪哇稻和粳稻品种对UVB抑制效应的敏感性存在品种差异。在日本水稻品种中，Sasanishiki表现出对UVB的抗性，而Norin 1的抗性较低。在这项工作中，我们研究了由UVB引起的环丁基嘧啶二聚体频率（CPD^S）的差异是否涉及UV敏感和UV抗性cvs。Norin 1和Sasanishiki我们还研究了在可见光辐射下生长的水稻叶片中UVB引起的CPD在不同时期的变化。我们改进了Sutherland等人设计的单向脉冲场凝胶电泳的碱性琼脂糖凝胶电泳。（1987年）。使用该装置，我们首先发现Norin 1比Sasanishiki更缺乏通过光复活和切除的CPD的修复能力。将完全展开的不同时期的叶片从植株上分离下来，暴露于UVB（9 KJ/m2），在完全展开的第2、3、4叶产生的CPD最高。用上述剂量的UVB照射小麦第6叶，从出苗到完全展开，观察了第6叶不同叶龄叶片中UVB引起的CPD的变化，第6叶在出苗后第1、4、7、15天完全展开，第7天完全展开。最高的CPD被认为是在4天生长的叶片中产生的。由此可见，随着生长和叶龄的变化，对UVB的敏感性会发生显著的变化。

We previously fornd that UVB reduced tiller number and biomass, and the amounts of soluble protein, Rubisco and so on in leaves of rice. There were cultivar differences in the sensitivity to the inhibitory effects of UVB among indica, javanica and japonica rice cultivars. Among Japanese rice cultivars, Sasanishiki exhibited more resistance to UVB,while Norin 1 was less resistant. In this work, we examined if differences in cyclobutyl pyrimidine dimer frequencies (CPD^S) caused by UVB were involved in UV-sensitive and UV-resistant cvs. Norin 1 and Sasanishiki. We also investigated the changes in UVB-caused CPDs in leaf developed at the different stages in rice grown in visible radiation without UVB.We improved an alkaline agarose gel electrophoresis using unidirectional pulse field gel electrophoresis devised by Sutherland et al.(1987). Using this apparatus, we first found that Norin 1 was more deficient in the repair ability of CPDs by photoreactivation and excision than Sasanishiki. The leaf fully expanded at the different stages was detache from plant, and exposed to UVB (9KJ/m2) : the highest CPDs were shown to be produced in the 2,3 and 4th fully expanded leaf. Furthemore, the changes of UVB-caused CPDs were examined in the different aged-leaf of the 6th leaf from leaf emergence through completion of expansion.The leaf grown for 1,4,7 and 15 days after leaf emergence was exposed to the above mentioned dose of UVB.The 6th leaf was fully expanded 7 days after emergence. The highest CPDs were found to be produced in the 4 days-grown leaf. It was thus indicated that the sensitivity to UVB caused CPDs dramatically changed in the progress of growth and leaf age.