【作者】 罗靖；

【导师】 高俊平； 马男；

【作者基本信息】 中国农业大学 ， 园林植物与观赏园艺， 2013， 博士

【摘要】 乙烯调控了植物生长发育的多个方面。在月季花朵开放过程中,乙烯发挥了一个重要作用。在月季切花采后流通过程中,环境中积累的乙烯导致花朵开放异常,造成重大经济损失。已有研究表明,乙烯对月季花朵开放的影响,部分是由于乙烯抑制了月季花瓣表皮细胞的扩展,进而影响到花朵开放,然而这一潜在的分子调节机理目前尚不明确。这里,我们的研究结果表明,乙烯对月季花瓣中表皮细胞扩展的抑制部分是通过一个生长抑制子RhGAI1介导的。乙烯诱导了RhGAI1的表达,而乙烯抑制齐1-MCP抑制了它的表达。在乙烯受体家族RhETRs沉默的月季花瓣样本中,RhGAI1的表达受到诱导。并且,在携带RhGAI1启动子的ein2和Col-0野生型转基因拟南芥中,乙烯信号的阻断改变了RhGAI1的表达模式。更进一步,原生质体瞬时表达结果表明,EIN3家族成员RhEIN3-3强烈诱导了RhGAI1的启动子活性。通过EMSA实验,还验证了RhEIN3-3和RhGAI1启动子的直接结合,证明RhGAI1是RhEIN3-3的一个直接下游基因。此外,RhGAI1调节了花瓣细胞的扩展,在拟南芥中过表达RhGAI1,抑制了花瓣细胞的扩展,而在月季花瓣中沉默RhGAI1,则促进了花瓣细胞的扩展。RhGAI1还调节了一系列细胞扩展相关功能基因的表达。其中,RhGAI1沉默的月季花瓣中,RhCesA2的表达受到明显的诱导,并且在原生质体瞬时表达中,RhGAI1还强烈抑制了RhCesA2的启动子活性。通过EMSA实验,还验证了RhGAI1和RhCesA2启动子的直接结合,证明RhCesA2是RhGAI1的一个直接下游基因。这些结果表明,响应乙烯的生长抑制子RhGAI1作用于RhEIN3-3的下游,调控了RhCesA2等一系列细胞扩展相关的下游功能基因的转录,从而参与了乙烯调节的月季花瓣扩展过程。本研究揭示了乙烯对RhGAI1的转录调节机理,有助于了解乙烯调控月季花瓣扩展的分子机制。更多还原

【Abstract】 The phytohormone ethylene regulates multiple aspects of plant growth and development. Ethylene influences the flower opening in roses by repressing the expansion of abaxial sub-epidermis cells in rose petals. However, the molecular mechanism underlying this process is not very clear. Here, we reported that ethylene-regulated cell expansion in rose petals was partly mediated by a growth repressor RhGAIl. Ethylene induced the expression of RhGA11, while ethylene inhibitor1-MCP suppressed its expression. And, silencing of RhETRs in rose petals increased the expression of RhGAI1. In transgenic Arabidopsis ein2mutant seedlings carrying the proRhGAI1::GUS, interruption of ethylene signaling changed the expression pattern of RhGAI1. Further, RhEIN3-3strongly induces the promoter activity of RhGAIl in Arabidopsis protoplasts. By EMSA assay, we found that RhEIN3-3could bind to the promoter of RhGAI1, which indicated that RhGAI1was a direct target of RhEIN3-3. We also found that RhGAI1regulated the expansion of petal cells. Over-expression of RhGAIl restrained the expansion of abaxial sub-epidermis cells in Arabidopsis petals, while silencing of RhGAI1promoted the expansion of abaxial sub-epidermis cells in rose petals. What’s more, RhGAI1regulated the expression of a couple of cell expansion-related genes, which were possibly responsible for inhibition of petal expansion by RhGAIl. The promoter activity of RhCesA2is intensively repressed by RhGAIl. By EMSA assay, we found that RhGAIl could bind to the promoter of RhCesA2, which indicated that RhCesA2was a direct target of RhGAIl. Taken together, these results demonstrated that the expression of RhGAI1is induced by ethylene, and RhGAIl restrained the expansion of rose petals partly by regulating the expression of several cell expansion-related genes. This work uncovers the transcriptional regulation of RhGAI1by ethylene and provides a better understanding of how ethylene regulates petal expansion in roses.更多还原