PEAPOD regulates lamina size and curvature in Arabidopsis

Abstract

Although a complex pattern of interspersed cell proliferation and cell differentiation is known to occur during leaf blade development in eudicot plants, the genetic mechanisms coordinating this growth are unclear. In Arabidopsis, deletion of the PEAPOD (PPD) locus increases leaf lamina size and results in dome-shaped rather than flat leaves. Siliques are also altered in shape because of extra lamina growth. The curvature of a ⌬ppd leaf reflects the difference between excess growth of the lamina and a limitation to the extension capacity of its perimeter. Excess lamina growth in ⌬ppd plants is due to a prolonged phase of dispersed meristematic cell (DMC) proliferation (for example, the meristemoid and procambium cells that form stomatal stem cells and vascular cells, respectively) during blade development. The PPD locus is composed of two homologous genes, PPD1 and PPD2, which encode plantspecific putative DNA-binding proteins. Overexpression of PPD reduces lamina size by promoting the early arrest of DMC proliferation during leaf and silique development. Therefore, by regulating the arrest of DMC proliferation, the PPD genes coordinate tissue growth, modulate lamina size, and limit curvature of the leaf blade. I propose a revised model of leaf development with two cell-cycle arrest fronts progressing from the tip to the base: the known primary front, which determines arrest of general cell proliferation, followed by a secondary front that involves PPD and arrests DMC division.cell proliferation ͉ coordinated growth ͉ leaf development

Computational Method for Quantifying Growth Patterns at the Adaxial Leaf Surface in Three Dimensions

“…A downward-curving growth gradient indicates that at any point along the proximodistal axis of the leaf, the sides of the leaf grow slower than the center. This should lead to an increased curvature of the leaf across the transverse axis during the days where the gradient is clearly downward curving; this concept is exaggerated in the Arabidopsis peapod mutant, whose dome-shaped leaf phenotype is explained by excess growth of the lamina but not the perimeter (White, 2006). By the same token, as the growth gradient becomes straighter or upward curving, the leaf transverse curvature should decrease.…”

Increasing seed size and quality by manipulating BIG SEEDS1 in legume species

“…It is related to two tandemly repeated genes in Arabidopsis, At4g14713 (PEAPOD1 or PPD1) and At4g14720 (PPD2), that have been shown to regulate the size and shape of leaves and siliques but not seeds (20,21). Protein subcellular localization showed that BS1-GFP fusion proteins were localized to the nucleus (Fig.…”

“…Arabidopsis PPD1 and PPD2, the BS1 orthologs, repress meristemoid cell division in leaves (20,21)). In loss-of-function and knock-down ppd mutants, numerous small cells that surround stomata were generated, giving rise to enlarged and dome-shaped leaves (20-22) (SI Appendix, Fig.…”

The ArabidopsisGRF-INTERACTING FACTORGene Family Performs an Overlapping Function in Determining Organ Size as Well as Multiple Developmental Properties

“…ANT, KLU, and SWP encode the APETALA2 domain transcription factor, the P450 cytochrome oxidase CYP78A5, and the Med150/RGR1-like subunits of the Mediator transcriptional regulatory complex, respectively. There are also negative regulators of cell proliferation and organ growth, such as PEAPOD and BIG BROTHER genes, which encode putative DNA-binding proteins and an E3 ubiquitin ligase, respectively (Disch et al, 2006;White, 2006). Those negative regulators affect the duration of cell proliferation in lateral organs as well.…”