Gibberellin partly mediates LANCEOLATE activity in tomato

Abstract

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.

Leaf development and morphogenesis

“…4). Interestingly, GA and cytokinin were both shown to modulate this late morphogenetic activity in tomato (Shani et al, 2010;Yanai et al, 2011). Cumulatively, these studies suggest that the flexibility of leaf shape is achieved by tuning the balance between hormones that promote indeterminate state, such as cytokinin, and hormones that promote differentiation, such as GA.…”

“…These effects on GA homeostasis mediate the function of KNOXI in tuning the SAM-leaf boundary and in modulating compound leaf development in Arabidopsis, maize, tobacco and tomato Hay et al, 2002;Jasinski et al, 2005;Sakamoto et al, 2001). By contrast, the TCP protein LA positively affects GA homeostasis in tomato (Yanai et al, 2011). Modulation of GA homeostasis therefore appears to be a common mechanism by which different transcription factors tune the rate of maturation and differentiation.…”

CLAUSA is a MYB Transcription Factor that Promotes Leaf Differentiation by Attenuating Cytokinin Signaling

“…The morphogenetic stage is particularly long in tomato, resulting in a wide diversity of leaf forms and unique developmental flexibility (Bar and Ori, 2014;Bar et al, 2015;. Recent studies have uncovered an even higher potential for prolonged morphogenesis in tomato leaf development, which is normally restricted by differentiation-promoting factors (Bar et al, 2015;Shani et al, 2010;Yanai et al, 2011). Characterization of mutants with extended or restricted morphogenesis has pointed to this potential and led to the identification of factors that balance morphogenesis and differentiation during leaf development (Sluis and Hake, 2015;Canales et al, 2010;Efroni et al, 2010;Bar and Ori, 2014;Blein et al, 2010).…”

“…By contrast, transcription factors from the CIN-TCP (CINNCINATA-TEOSINTE BRANCHED1-CYCLOIDEA-PCF) family, belonging to class II TCPs, restrict the morphogenetic window and promote differentiation Efroni et al, 2008;Shleizer-Burko et al, 2011;Ori et al, 2007;Palatnik et al, 2003). The hormone gibberellin also promotes differentiation and partially mediates CIN-TCP function in this process (Yanai et al, 2011;Fleishon et al, 2011;Van Tuinen et al, 1999;Jasinski et al, 2008). The ratio of SINGLE FLOWER TRUSS and SELF PRUNING has also been shown to affect the balance between growth and differentiation in many developmental processes including leaf development, in addition to their role in regulating flowering time (Lifschitz et al, 2014;Shalit et al, 2009).…”

A inter-relação entre a via miR156/SBP e o fitormônio giberelina no controle da transição de fase vegetativo-reprodutivo em tomateiro

“…Dessa forma, a via miR319/LA em tomateiro controla a biossíntese de GA em alguns tecidos (YANAI et al, 2011).…”