[Expression and functional analysis of SUA41gene in Arabidopsis thaliana]

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 temperature 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 decreased 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 flowering time of Arabidopsis.