植物的开花受多条途径的控制, 其中包括光周期途径、春化途径、赤霉素途径、自主途径和温敏途径。SUA41(SUMO substrate in Arabidopsis 41)是本实验室筛选到的、SUMO(Small ubiquitin modifier)的潜在底物, 并且前人的研究发现它参与自主途径的开花调节, 但其对开花时间的调节机制没有详细报道。文章对SUA41基因的表达、sua41突变体对不同环境条件的反应以及SUA41对开花时间调节的可能机制进行初步分析。结果显示, 与野生型相比, sua41突变体在常温或低温、长日或者短日条件下均为早花, 并且在低温和常温下的开花时间没有太大差别。过表达SUA41能够恢复sua41突变体的早花表型。SUA41基因在拟南芥的幼苗、根、茎、叶和花以及各个植物发育阶段都有表达, 说明SUA41基因是一个组成型表达基因。SUA41基因的表达与GA处理无关, 长日低温条件能够诱导SUA41基因的表达, 且在温敏途径突变体fve和fca中SUA41基因的表达量减少。与野生型比较, sua41突变体中CO基因的mRNA表达量没有明显变化, FT和SOC1基因表达量增加且FT增加幅度更大, FLC的mRNA表达量减少。结果表明SUA41基因虽然在自主途径中起作用, 但主要在温敏途径中参与拟南芥开花时间调节。
In plants, multiple floral induced-pathways including photoperiod signaling, vernalization signaling, autonomous pathway, gibberellin signaling, and thermosensory signaling are well known to mediate signaling from different cues to confer flowering regulation. SUA41 (SUMO substrate 41) is a SUMO (Small ubiquitin modifier) substrate screened out in our laboratory. Previous reports indicate that the SUA41 gene is involved in autonomous pathway to regulate flowering time of Arabidopsis, but its mechanism remains to be elucidated. In this study, the spatiotemporal expression pattern for SUA41, responses of its mutant to environmental factors, and its regulation of mechanism of flowering time were investigated. The sua41 mutant flowered earlier than Col-0 at both normal temperature (22℃) and low temperature (16℃) under long day (LD) or short day (SD) conditions. In addition, the flowering times of sua41 had no significant difference between 22℃ and 16℃ conditions. Over-expression of SUA41 rescued the early flowering phenotype of the sua41 mutant. Expression of SUA41 was at similar levels in seedlings, roots, stems, leaves, flowers, or the samples at all developmental stages examined, suggesting that SUA41 is a constitutive expression gene. Expression of SUA41 mRNA was not responsive to GA treatment, but highly induced by low tem-perature and inhibited in fve and fca mutants defective in the thermosensory pathway. Compared with Col-0, the expression levels of FT and SOC1 increased, whereas the expression level of FLC mRNA de-creased and CO expression was not significantly altered in the sua41 mutant. The results showed that the SUA41 gene plays a role in not only the autonomous pathway but also the thermosensory pathway to regulate flow-ering time of Arabidopsis.
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