Control of Leaf Morphogenesis by Long- and Short-Distance Signaling: Differentiation of Leaves Into Sun or Shade Types and Compensated Cell Enlargement

Abstract

The flattened, thin lamina of leaves captures sunlight for photosynthesis and facilitates gas exchange. Therefore, the size and shape of a leaf are fundamentally important features of its integrity and function. Progress in developmental studies has suggested that long-and short-distance signaling pathways are involved in leaf formation. In this chapter, we introduce these signaling pathways, both of which can control final leaf shape and structure: a long-distance signaling pathway that governs the differentiation of leaves into sun and shade types, and a short-distance signaling pathway that appears to be involved in an organ-wide system that integrates cell proliferation and cell enlargement. Although none of the molecules involved in these two pathways have been identified, plausible mechanisms of these pathways are discussed based on present data.

Exogenous Cytokinin Promotes Epipremnum aureum L. Growth through Enhanced Dry Weight Assimilation rather than through Changes in Partitioning

“…Although we have not attempted to determine whether or not part of the increased nitrogen concentration corresponds to enzymes involved in carbon fixation, this possibility seems likely, since cytokinins have been reported to promote synthesis of Rubisco [35]. Furthermore, BAP might promote leaf blade thickening, thus leading to an increase in the levels of photosynthetic machinery per unit leaf area [36]. SLA reflects biomass per unit leaf area and is well correlated to leaf thickness [37].…”

Keep an Eye on PPi: The Vacuolar-Type H+-Pyrophosphatase Regulates Postgerminative Development inArabidopsis

“…Because decreased cell numbers trigger the unusual cell enlargement observed in compensation-exhibiting mutants (Ferjani et al, 2007(Ferjani et al, , 2008Tsukaya, 2008), we next assessed whether exogenously supplied Suc affects cell size in fully expanded cotyledons. Consistently, cell size was normal in fugu5-1 mutants grown in the presence of Suc ( Figure 1E).…”

“…Although leaf developmental dynamism has been the subject of vigorous research (Donnelly et al, 1999;White, 2006;Ferjani et al, 2007;Usami et al, 2009), little is known about leaf size-coordinating mechanisms (Ingram and Waites, 2006;Anastasiou and Lenhard, 2007;Ferjani et al, 2008;Tsukaya, 2008;Micol, 2009;Krizek, 2009). Recently, emerging data indicate that an organ-wide coordination of cell proliferation and postmitotic cell expansion underlies leaf organogenesis and regulates leaf size (Tsukaya, 1998(Tsukaya, , 2002(Tsukaya, , 2005(Tsukaya, , 2006(Tsukaya, , 2008Horiguchi et al, 2006a).…”

Themore and smaller cellsmutants ofArabidopsis thalianaidentify novel roles forSQUAMOSA PROMOTER BINDING PROTEIN-LIKEgenes in the control of heteroblasty

“…Plants have the ability to make leaves of amazingly diverse sizes and shapes, not only between different species but also within a species. The size and shape of leaves change dramatically in response to environmental conditions, such as light quality and quantity, daylength, nutrition and water availability (Ferjani et al, 2008). In addition to these external cues, internal signals that arise at certain developmental stages have a role in the regulation of leaf size and shape.…”