Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, P.O. Box 6, 50250 Bet Dagan, Israel.
Plant Mol Biol. 2012 Apr;78(6):561-76. doi: 10.1007/s11103-012-9883-4.
Auxin response factors (ARFs) are plant transcription factors that activate or repress the expression of auxin-responsive genes and accordingly, play key roles in auxin-mediated developmental processes. Here we identified and characterized the Solanum lycopersicum (tomato) ARF10 homolog (SlARF10), demonstrated that it is posttranscriptionally regulated by Sl-miR160, and investigated the significance of this regulation for tomato development. In wild-type tomato, SlARF10 is primarily expressed in the pericarp of mature and ripened fruit, showing an expression profile complementary to that of Sl-miR160. Constitutive expression of wild-type SlARF10 did not alter tomato development. However, transgenic tomato plants that constitutively expressed the Sl-miR160a-resistant version (mSlARF10) developed narrow leaflet blades, sepals and petals, and abnormally shaped fruit. During compound leaf development, mSlARF10 accumulation specifically inhibited leaflet blade outgrowth without affecting other auxin-driven processes such as leaflet initiation and lobe formation. Moreover, blade size was inversely correlated with mSlARF10 transcript levels, strongly implying that the SlARF10 protein, which was localized to the nucleus, can function as a transcriptional repressor of leaflet lamina outgrowth. Accordingly, known auxin-responsive genes, which promote cell growth, were downregulated in shoot apices that accumulated increased mSlARF10 levels. Taken together, we propose that repression of SlARF10 by Sl-miR160 is essential for auxin-mediated blade outgrowth and early fruit development.
生长素响应因子（ARFs）是植物转录因子，它们激活或抑制生长素响应基因的表达，因此在生长素介导的发育过程中发挥关键作用。在这里，我们鉴定并表征了番茄（Solanum lycopersicum）ARF10 同源物（SlARF10），证明其受到 Sl-miR160 的转录后调控，并研究了这种调控对番茄发育的重要性。在野生型番茄中，SlARF10 主要在成熟和成熟果实的果皮中表达，其表达模式与 Sl-miR160 互补。野生型 SlARF10 的组成型表达不会改变番茄的发育。然而，组成型表达 Sl-miR160a 抗性版本（mSlARF10）的转基因番茄植物发育出狭窄的小叶叶片、萼片和花瓣以及形状异常的果实。在复叶发育过程中，mSlARF10 的积累特异性抑制小叶叶片的生长，而不影响其他生长素驱动的过程，如小叶的起始和裂片的形成。此外，叶片大小与 mSlARF10 转录本水平呈负相关，强烈暗示 SlARF10 蛋白定位于细胞核，可以作为小叶叶片生长的转录抑制子。因此，促进细胞生长的已知生长素响应基因在积累增加的 mSlARF10 水平的茎尖中下调。综上所述，我们提出 Sl-miR160 对 SlARF10 的抑制对于生长素介导的叶片生长和早期果实发育是必不可少的。
