拟南芥LHY基因超表达与成花转变

The floral transition of LHY overexpression plants in Arabidopsis thaliana

高等植物的成花转变受到多个基因网络的调控,植物从营养生长转变为生殖生长,与植物自身发育的生物节律相关,然而生物钟(circadian clock)相关基因在其中的调控作用仍不清楚。本研究通过构建超表达载体pCAMBIA-3301-35S::LHY,遗传转化后获得超表达植株,分析超表达生物节律基因LHY对成花转变的影响。结果表明,LHY超表达植株具有18片莲座叶,野生型植株为12片;LHY超表达植株在第33天出现可见花芽,野生型植株则为20 d,超表达植株表现出晚花表型。茎端分生组织解剖结构分析表明,LHY超表达植株在第19天(野生型植株15 d)时生长锥持续生长发育,凸起明显增高,具多层原套细胞,原体和髓分生组织细胞分裂,数量增多,说明超表达植株营养生长成熟期延迟,导致晚花。qRT-PCR对miR156及其靶基因SPL3表达水平检测结果表明,LHY超表达植株的miR156表达量随植物发育进程逐渐降低,而SPL3表达量则逐渐升高,LHY超表达植株可能通过调控miR156和SPL3的表达量来调控成花转变。

The floral transition in higher plants is regulated by multiple gene network.The transition of plants from vegetative growth to reproductive growth is related to the biological rhythm of plant development.However,the regulatory role of circadian clock-related genes in it is still unclear.By constructing the overexpression vector pCAMBIA-3301-35S::LHY,and the following genetic transformation,the effects of overexpression of circadian clock-related gene LHY on floral transition were analyzed with overexpression plants.The results showed that LHY overexpression plants had 18 rosette leaves,while only 12 existed in wild-type plants.LHY overexpression plants had visible flower buds on 33rd day,while wild-type plants were on the 20th day.The overexpressed plants showed late flower phenotype.The anatomical structure analysis of the shoot apical meristem showed that the growth cone of LHY overexpression plants continued to grow and develop to a prominent height on the 19th day(compared to 15th day in wild-type plants),with multiple layers of tunica,corpus and pith meristem zone cells.These indicated that overexpression plants had delayed vegetative growth and maturity,leading to late flowering.The results of qRT-PCR on the expression level of miR156 and its target gene SPL3 showed that LHY overexpression plants regulated the floral transition by down-regulating and up-regulating the expression levels of miR156 and SPL3 during plant growth.