The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Center for Agricultural Biotechnology, Hebrew University, Rehovot 76100, Israel.
Plant J. 2011 Nov;68(4):571-82. doi: 10.1111/j.1365-313X.2011.04716.x. Epub 2011 Aug 30.
Elaboration of a compound leaf shape depends on extended morphogenetic activity in developing leaves. In tomato (Solanum lycopersicum), the CIN-TCP transcription factor LANCEOLATE (LA) promotes leaf differentiation. LA is negatively regulated by miR319 during the early stages of leaf development, and decreased sensitivity of LA mRNA to miR319 recognition in the semi-dominant mutant La leads to prematurely increased LA expression, precocious leaf differentiation and a simpler and smaller leaf. Increased levels or responses of the plant hormone gibberellin (GA) in tomato leaves also led to a simplified leaf form. Here, we show that LA activity is mediated in part by GA. Expression of the SlGA20 oxidase1 (SlGA20ox1) gene, which encodes an enzyme in the GA biosynthesis pathway, is increased in gain-of-function La mutants and reduced in plants that over-express miR319. Conversely, the transcript levels of the GA deactivation gene SlGA2 oxidase4 (SlGA2ox4) are increased in plants over-expressing miR319. The miR319 over-expression phenotype is suppressed by exogenous GA application and by a mutation in the PROCERA (PRO) gene, which encodes an inhibitor of the GA response. SlGA2ox4 is expressed in initiating leaflets during early leaf development. Its expression expands as a result of miR319 over-expression, and its over-expression leads to increased leaf complexity. These results suggest that LA activity is partly mediated by positive regulation of the GA response, probably by regulation of GA levels.
复叶的形态发育依赖于发育叶片中延伸的形态发生活性。在番茄（Solanum lycopersicum）中，CIN-TCP 转录因子 LANCEOLATE（LA）促进叶片分化。在叶片发育的早期阶段，miR319 负调控 LA，而半显性突变体 La 中 LA mRNA 对 miR319 识别的敏感性降低导致 LA 表达过早增加、叶片提前分化以及叶片更简单和更小。番茄叶片中植物激素赤霉素（GA）水平或响应的增加也导致叶片形态简化。在这里，我们表明 LA 活性部分通过 GA 介导。SlGA20 氧化酶 1（SlGA20ox1）基因的表达增加，该基因编码 GA 生物合成途径中的一种酶，在功能获得性 La 突变体中增加，在过度表达 miR319 的植物中减少。相反，GA 失活基因 SlGA2 氧化酶 4（SlGA2ox4）的转录水平在过度表达 miR319 的植物中增加。miR319 过表达表型被外源 GA 处理和 PROCERA（PRO）基因的突变所抑制，该基因编码 GA 反应的抑制剂。SlGA2ox4 在早期叶片发育过程中在起始小叶中表达。由于 miR319 的过表达，其表达扩大，其过表达导致叶片复杂性增加。这些结果表明，LA 活性部分通过 GA 反应的正调控来介导，可能通过调节 GA 水平来实现。
