Higginson Trudi, Li Song Feng, Parish Roger W
Department of Botany, La Trobe University, Bundoora Campus, Bundoora, Victoria 3083, Australia.
Plant J. 2003 Jul;35(2):177-92. doi: 10.1046/j.1365-313x.2003.01791.x.
The AtMYB103 gene is a member of the R2R3 MYB gene family in Arabidopsis thaliana. Using the GUS reporter gene, AtMYB103 expression was found to be restricted to the tapetum of developing anthers. Employing RT-PCR and in situ hybridisation, we now show that AtMYB103 is also expressed in trichomes. GUS expression in trichomes was obtained by incorporating the coding and 3'-untranslated regions of AtMYB103 into the promoter-GUS constructs. Sense and antisense technologies were used to downregulate AtMYB103 expression. In transgenic lines with reduced AtMYB103 transcript levels, pollen, tapetum and trichome development were altered. The majority of the pollen grains were distorted in shape and had reduced or no cytoplasmic content. Tapetal degeneration occurred early, and large opaque bodies appeared in the tapetal cytoplasm. In transgenic plants, trichomes on cauline and rosette leaves produced additional branches. These overbranched trichomes contained more nuclear DNA than the wild-type trichomes. The results indicate that AtMYB103 is required for tapetal development and microsporogenesis, and negatively regulates trichome endoreduplication linked to the trichome branching.
AtMYB103基因是拟南芥中R2R3 MYB基因家族的成员之一。利用GUS报告基因，发现AtMYB103的表达仅限于发育中的花药绒毡层。通过逆转录聚合酶链反应（RT-PCR）和原位杂交，我们现在表明AtMYB103也在毛状体中表达。通过将AtMYB103的编码区和3'非翻译区整合到启动子-GUS构建体中，获得了毛状体中的GUS表达。采用正义和反义技术下调AtMYB103的表达。在AtMYB103转录水平降低的转基因系中，花粉、绒毡层和毛状体的发育发生了改变。大多数花粉粒形状扭曲，细胞质含量减少或没有。绒毡层过早退化，绒毡层细胞质中出现大的不透明体。在转基因植物中，茎生叶和莲座叶上的毛状体产生了额外的分支。这些过度分支的毛状体比野生型毛状体含有更多的核DNA。结果表明，AtMYB103是绒毡层发育和小孢子发生所必需的，并负调控与毛状体分支相关的毛状体核内复制。
