Molecular analysis of UV-B protection and of UV-B signaling in soybean.

1.UV-B反应转录因子GmMYB29B1在大豆中的功能：(1)GmMYB29B1(B1)在酵母中表达，其C-末端29个氨基酸残基是激活域的必要条件和充分条件。(2)将其DNA结合域在大肠杆菌中表达，并进行了凝胶迁移率改变分析(EMSA)。BD与大豆查尔酮合成酶基因(Gmchs)启动子上的H-box序列发生特异的相互作用。(3)将B1编码区插入豆科病毒载体(PCIYVV)中，将其插入蚕豆中。结果表明，接种计划促进了花青素的积累和CHS的表达，表明B1在体内也是CHS的转录激活剂。2.氮素营养受限条件下R2R3-MYB转录因子的分离。(1)分离到3个荷花基因(LjMYB101、LjMYB102和LjMYB103)，编码R2R3-MYB转录因子。此外，还分离到一个大豆同源基因LjMYB101，命名为GmMYB101。(2)LjMYB101只对根中的硝酸盐有反应，而LjMYB103只对地上部有反应。考虑到它们的系统发育关系，这两个基因似乎通过获得器官特异性反应性而产生分歧，这可能是它们的生理功能不同的原因。(3)在大肠杆菌中表达的LjMYB101的DNA结合域与H-box序列及其相关的MYB Type IID序列特异地相互作用。结果表明，LjMYB101是CHS和Gln1的转录因子，在低氮条件下表达上调。

1.Function of UV-B responsive transcription factor GmMYB29B1 in soybean.(1)GmMYB29B1(B1) was expressed in yeast was found to function as a transcriptional activator and its C-terminal region of 29 amino acid residues was both necessary and sufficient as the activator domain in the yeast system.(2)The DNA binding domain of B1(BD) expressed in E coli was used for electrophoretic mobility-shift assay(EMSA). BD interacted specifically with H-box sequence on the promoters of soybean chalcone synthase genes(Gmchs).(3)A plasmid construct of B1 coding region inserted into a legume virus vector(pCIYVV) was inoculated into broad bean. It was found that both accumulation of anthocyanin and expression of CHS were enhanced in the inoculated plans, indicating that B1 functioned as a transcriptional activator of CHS, in vivo, as well.2.Isolation of R2R3-MYB transcription factors responsive to nitrogen nutrient-limited conditions.(1)Three Lotus genes (LjMYB101,LjMYB102, and LjMYB103), coding for R2R3-MYB transcription factors responsive to nitrogen nutrient-limited conditions were isolated. In addition, a candidate for the soybean orthologue of LjMYB101 was isolated and designated GmMYB101. They all belonged to subgroup 10 of the plant R2R3-MYB superfamily.(2)LjMYB101 was responsive to nitrate only in roots, while LjMYB103 was responsive only in shoots. Considering their phylogenetic relationship, the two genes seem to have diverged through acquisition of their organ-specific responsiveness, which might have differentiated their physiological roles.(3)The DNA binding domain of LjMYB101 expressed in E.coli interacted specifically with H-box sequence and its related MYB Type IID sequences. It was suggested that LjMYB101 functioned as a transcription factor of CHS and Gln1, which also showed up-regulated expression under low nitrogen conditions.