Symbiotic rhizobium and nitric oxide induce gene expression of non-symbiotic hemoglobin in Lotus japonicus
Symbiotic rhizobium and nitric oxide induce gene expression of non-symbiotic hemoglobin in Lotus japonicus
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DOI：
10.1093/pci/pci001
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发表时间：
2005-01-01
影响因子：
4.9
通讯作者：
Uchiumi, T
中科院分区：
文献类型：
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作者：
Shimoda, Y;Nagata, M;Uchiumi, T
我们表征了莲花非共生血红蛋白 (non-sym-Hb) 基因 LjHb1 和 LjHb2 的表达谱。尽管LjHb1和LjHb2在其cDNA序列中表现出77%的同源性，但LjHb2在植物Hb的系统发育树中处于独特的位置。两个基因的 5' 上游区域都包含基序 AAAGGG，其位置与其他非 sym-Hb 基因的启动子相似。定量RT-PCR获得的表达谱显示，LjHb1和LjHb2在成熟植物的所有组织中表达，并且在成熟根瘤中表达增强。 LjHb1 在缺氧和寒冷条件下以及通过应用一氧化氮 (NO) 供体强烈诱导，而 LjHb2 仅通过应用蔗糖诱导。 LjHb1 也通过接种共生根瘤菌 Mesorhizobium loti MAFF303099 短暂诱导。使用荧光显微镜观察发现，LjRb1 表达的诱导与 NO 的产生相对应。这些结果表明non-sym-Hb和NO在应激适应和豆科植物-根瘤菌共生的早期阶段具有重要作用。
We characterized the expression profiles of LjHb1 and LjHb2, non-symbiotic hemoglobin (non-sym-Hb) genes of Lotus japonicus. Although LjHb1 and LjHb2 showed 77% homology in their cDNA sequences, LjHb2 is located in a unique position in the phylogenetic tree of plant Hbs. The 5'-upstream regions of both genes contain the motif AAAGGG at a position similar to that in promoters of other non-sym-Hb genes. Expression profiles obtained by using quantitative RT-PCR showed that LjHb1 and LjHb2 were expressed in all tissues of mature plants, and expression was enhanced in mature root nodules. LjHb1 was strongly induced under both hypoxic and cold conditions, and by the application of nitric oxide (NO) donor, whereas LjHb2 was induced only by the application of sucrose. LjHb1 was also induced transiently by the inoculation with the symbiotic rhizobium Mesorhizobium loti MAFF303099. Observations using fluorescence microscopy revealed the induction of LjRb1 expression corresponded to the generation of NO. These results suggest that non-sym-Hb and NO have important roles in stress adaptation and in the early stage of legume-rhizobium symbiosis.