Tian Xueyi, Zou Pu, Miao Mingzhi, Ning Zulin, Liao Jingping
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, 510650, China.
Guiyang University, Jianlongdong Road 103, Nanming District, Guiyang, 550005, China.
Mol Genet Genomics. 2018 Apr;293(2):391-400. doi: 10.1007/s00438-017-1392-3. Epub 2017 Nov 14.
Proper establishment of adaxial-abaxial polarity is essential for the development of lateral organs, while former researches were mostly focused on the polarity regulation in leaves, and little is known in stamens, especially in the asymmetric ones. Canna indica (Zingiberales: Cannaceae) is a widely cultivated ornamental plant and the representative species to study the evolutionary development of Zingiberales. The androecium of Canna indica comprises 3-4 petaloid staminodes and a fertile stamen (FS), which consists of a one-theca anther and a petaloid appendage. The partially petaloid stamen is considered as an intermediate state organ from a two-thecae stamen to a completely petaloid staminode. Using RNA-Seq, we quantified the expressions of the transcripts in anther and petaloid appendage, and detected 64,430 and 57,041 unigenes in these two organs, respectively. 4574 unigenes were down-regulated, and 3525 were up-regulated in petaloid appendage compared with those in anther. GO enrichment analysis indicated that the function of cytokinin is more related to cell differentiation in anther, while auxin is more to cell division in petaloid appendage. B- and C-class floral homeotic genes were expressed in these two androecium parts. Most of the class III HD-ZIP family members, which specify adaxial identity, were expressed lower in petaloid appendage than in anther; while KANADIs and YABBYs, which promote abaxial identity, exhibited opposite expression patterns. In situ hybridization showed that the adaxial marker gene was mainly expressed in the region between the two protrusions of the anther, while the abaxial marker was mainly expressed in petaloid appendage. We hypothesize that the adaxial-abaxial polarity participates in the distinctive anther-petaloid appendage patterning within the asymmetric FS of Canna indica.
正确建立近轴-远轴极性对于侧生器官的发育至关重要，而先前的研究大多集中在叶片中的极性调控，对于雄蕊，尤其是不对称雄蕊中的极性调控了解甚少。美人蕉（姜目：美人蕉科）是一种广泛种植的观赏植物，也是研究姜目进化发育的代表性物种。美人蕉的雄蕊群由3-4个花瓣状退化雄蕊和一个可育雄蕊（FS）组成，可育雄蕊由单室花药和花瓣状附属物组成。部分花瓣状雄蕊被认为是从双室花药到完全花瓣状退化雄蕊的中间状态器官。利用RNA测序，我们对花药和花瓣状附属物中转录本的表达进行了定量分析，在这两个器官中分别检测到64430个和57041个单基因。与花药相比，花瓣状附属物中有4574个单基因下调，3525个上调。基因本体富集分析表明，细胞分裂素的功能与花药中的细胞分化更相关，而生长素与花瓣状附属物中的细胞分裂更相关。B类和C类花同源异型基因在这两个雄蕊部分均有表达。大多数决定近轴特性的III类HD-ZIP家族成员在花瓣状附属物中的表达低于花药；而促进远轴特性的KANADIs和YABBYs则表现出相反的表达模式。原位杂交显示，近轴标记基因主要在花药的两个突起之间的区域表达，而远轴标记主要在花瓣状附属物中表达。我们推测，近轴-远轴极性参与了美人蕉不对称可育雄蕊中花药-花瓣状附属物独特的模式形成。
