Responses of rice seedlings to UV‐B radiation (UV‐B) were investigated, aiming to establish rice as a model plant for UV‐B signalling studies. The growth of japonica rice coleoptiles, grown under red light, was inhibited by brief irradiation with UV‐B, but not with blue light. The effective UV‐B fluences (10⁻¹‐10³ μmol m⁻²) were much lower than those reported in Arabidopsis. The response was much less in indica rice cultivars and its extent varied among Oryza species. We next identified UV‐B‐specific anthocyanin accumulation in the first leaf of purple rice and used this visible phenotype to isolate mutants. Some isolated mutants were further characterized, and one was found to have a defect in the growth response. Using microarrays, we identified a number of genes that are regulated by low‐fluence‐rate UV‐B in japonica coleoptiles. Some up‐regulated genes were analysed by real‐time PCR for UV‐B specificity and the difference between japonica and indica. More than 70% of UV‐B‐regulated rice genes had no homologs in UV‐B‐regulated Arabidopsis genes. Many UV‐B‐regulated rice genes are related to plant hormones and especially to jasmonate biosynthetic and responsive genes in apparent agreement with the growth response. Possible involvement of two rice homologs of UVR8, a UV‐B photoreceptor, is discussed.

中文翻译：

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水稻中的 UV-B 信号：响应识别、基因表达谱和突变体分离

研究了水稻幼苗对 UV-B 辐射（UV-B）的响应，旨在将水稻作为 UV-B 信号研究的模型植物。在红光下生长的粳稻胚芽鞘的生长受到 UV-B 短暂照射的抑制，但不受蓝光的抑制。有效的 UV-B 能量密度 (10 ^-1 ‐10 ³ μmol m ^-2 ) 远低于拟南芥中报道的能量密度。籼稻品种的反应要小得多，其程度在水稻中有所不同物种。我们接下来确定了紫米第一片叶子中 UV-B 特异性花青素的积累，并使用这种可见的表型来分离突变体。一些分离的突变体被进一步表征，发现一种在生长反应中存在缺陷。使用微阵列，我们在粳稻胚芽鞘中鉴定了许多受低通量率 UV-B 调控的基因。通过实时 PCR 分析了一些上调基因的 UV-B 特异性以及粳稻和籼稻之间的差异. 超过 70% 的 UV-B 调控的水稻基因与 UV-B 调控的拟南芥基因没有同源性。许多 UV-B 调控的水稻基因与植物激素有关，尤其是茉莉酸生物合成和响应基因，与生长响应明显一致。讨论了 UV-B 光感受器 UVR8 的两个水稻同源物的可能参与。