Jing Danlong, Xia Yan, Chen Faju, Wang Zhi, Zhang Shougong, Wang Junhui
State Key Laboratory of Forest Genetics and Tree Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China.
Biotechnology Research Center, China Three Gorges University, Yichang City 443002, Hubei Province, PR China.
Plant Sci. 2015 Feb;231:40-51. doi: 10.1016/j.plantsci.2014.11.004. Epub 2014 Nov 25.
PISTILLATA (PI) plays crucial roles in Arabidopsis flower development by specifying petal and stamen identities. To investigate the molecular mechanisms underlying organ development of woody angiosperm in Catalpa, we isolated and identified a PI homologue, referred to as CabuPI (C. bungei PISTILLATA), from two genetically cognate C. bungei (Bignoniaceae) bearing single and double flowers. Sequence and phylogenetic analyses revealed that the gene is closest related to the eudicot PI homologues. Moreover, a highly conserved PI-motif is found in the C-terminal regions of CabuPI. Semi-quantitative and quantitative real time PCR analyses showed that the expression of CabuPI was restricted to petals and stamens. However, CabuPI expression in the petals and stamens persisted throughout all floral development stages, but the expression levels were different. In 35S::CabuPI transgenic homozygous pi-1 mutant Arabidopsis, the second and the third whorl floral organs produced normal petals and a different number of stamens, respectively. Furthermore, ectopic expression of the CabuPI in transgenic wild-type or heterozygote pi-1 mutant Arabidopsis caused the first whorl sepal partially converted into a petal-like structure. These results clearly reveal the functional conservation of PI homologues between C. bungei and Arabidopsis.
PISTILLATA（PI）通过决定花瓣和雄蕊的特征，在拟南芥花发育中发挥关键作用。为了研究梓树中木质被子植物器官发育的分子机制，我们从两株具有单花和重瓣花的亲缘关系相近的楸树（紫葳科）中分离并鉴定出一个PI同源基因，命名为CabuPI（楸树PISTILLATA）。序列和系统发育分析表明，该基因与双子叶植物的PI同源基因关系最为密切。此外，在CabuPI的C端区域发现了一个高度保守的PI基序。半定量和实时定量PCR分析表明，CabuPI的表达仅限于花瓣和雄蕊。然而，CabuPI在花瓣和雄蕊中的表达在整个花发育阶段持续存在，但表达水平有所不同。在35S::CabuPI转基因纯合pi-1突变拟南芥中，第二轮和第三轮花器官分别产生了正常的花瓣和不同数量的雄蕊。此外，CabuPI在转基因野生型或杂合pi-1突变拟南芥中的异位表达导致第一轮萼片部分转化为花瓣状结构。这些结果清楚地揭示了楸树和拟南芥之间PI同源基因的功能保守性。
