Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.
Plant Cell Physiol. 2010 Jan;51(1):103-13. doi: 10.1093/pcp/pcp171. Epub 2009 Dec 10.
The post-translational conjugation of small ubiquitin-related modifiers (SUMOs) to other proteins is involved in regulation of many processes in eukaryotic development; although its role in plant development is beginning to be dissected. Previously, we demonstrated that the siz1 mutant, which is impaired in SUMO E3 ligase, showed a dwarf-like shoot phenotype with accumulation of salicylic acid (SA), and the expression of nahG, a bacterial salicylate hydroxylase that catabolizes SA, in siz1 reduced the SA level and suppressed dwarfism. Herein, we provide evidence that the SIZ1 gene controls cell division and elongation through regulation of the SA level. Mature siz1-2 and siz1-3 plants exhibited a dwarf-like shoot phenotype that is attributable to decreased leaf cell volume and number relative to the wild type. Cell division and expansion defects caused by siz1 were also suppressed by the expression of nahG. Expression of XTH8 and XTH31, encoding xyloglucan endotransglycosylase/hydrolase, which are thought to facilitate leaf cell expansion, was down-regulated in siz1 leaves. However, reduced XTH8 and XTH31 expression in siz1 plants was restored in nahG siz1-2 plants. These results indicate that SIZ1 regulates cell growth and plant development with regulation of SA accumulation. Also, XTH8 and XTH31 genes may be responsible for reduced leaf cell expansion.
小泛素相关修饰物（SUMO）的翻译后缀与其他蛋白质的缀合参与了真核生物发育过程中许多过程的调节；尽管其在植物发育中的作用才刚刚开始被剖析。以前，我们证明了 siz1 突变体，其 SUMO E3 连接酶受损，表现出类似于矮化的芽表型，并且 nahG 的表达，一种细菌水杨酸羟化酶，可分解水杨酸，在 siz1 中降低了水杨酸水平并抑制了矮化。在此，我们提供的证据表明，SIZ1 基因通过调节水杨酸水平来控制细胞分裂和伸长。成熟的 siz1-2 和 siz1-3 植物表现出类似于矮化的芽表型，这归因于相对于野生型的叶片细胞体积和数量减少。 siz1 引起的细胞分裂和扩展缺陷也被 nahG 的表达所抑制。编码木葡聚糖内切糖基转移酶/水解酶的 XTH8 和 XTH31 的表达，被认为有助于叶片细胞的扩展，在 siz1 叶片中下调。然而，nahG siz1-2 植物中恢复了 siz1 植物中降低的 XTH8 和 XTH31 表达。这些结果表明，SIZ1 通过调节水杨酸的积累来调节细胞生长和植物发育。此外，XTH8 和 XTH31 基因可能负责减少叶片细胞的扩展。
