Leaf shape: genetic controls and environmental factors

Abstract

In recent years, many genes have been identified that are involved in the developmental processes of leaf morphogenesis. Here, I review the mechanisms of leaf shape control in a model plant, Arabidopsis thaliana, focusing on genes that fulfill special roles in leaf development. The lateral, two-dimensional expansion of leaf blades is highly dependent on the determination of the dorsoventrality of the primordia, a defining characteristic of leaves. Having a determinate fate is also a characteristic feature of leaves and is controlled by many factors. Lateral expansion is not only controlled by general regulators of cell cycling, but also by the multi-level regulation of meristematic activities, e.g., specific control of cell proliferation in the leaf-length direction, in leaf margins and in parenchymatous cells. In collaboration with the polarized control of leaf cell elongation, these redundant and specialized regulating systems for cell cycling in leaf lamina may realize the elegantly smooth, flat structure of leaves. The unified, flat shape of leaves is also dependent on the fine integration of cell proliferation and cell enlargement. Interestingly, while a decrease in the number of cells in leaf primordia can trigger a cell volume increase, an increase in the number of cells does not trigger a cell volume decrease. This phenomenon is termed «compensation» and suggests the existence of some systems for integration between cell cycling and cell enlargement in leaf primordia via cell-cell communication. The environmental adjustment of leaf expansion to light conditions and gravity is also summarized.

Mapping shape quantitative trait loci using a radius-centroid-contour model

“…Comparing the anatomical and shape feature of organisms has been a central element of biology for centuries (Bookstein, 1978;Monteiro et al, 2002;Adams et al, 2004). For example, as one of the most conspicuous aspects of a plant's phenotype, leaf shape has been used to provide an intricate link between biological structure and function in changing environments (Tsukaya, 2005). With an increasing interest in studying shape genetics (Weber et al, 1999;Langlade et al, 2005;Leamy et al, 2008), we have now developed a computational model for mapping specific QTLs that contribute to shape variation by using leaf shape as an example of demonstration.…”

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

“…Plant organ development is the result of strict spatial and temporal genetic control and the coordination of cell division, growth, and differentiation (Beemster et al, 2003;Tsukaya, 2005;Harashima and Schnittger, 2010;Gonzalez et al, 2012). However, the role of cell cycle regulation and cell division in plant growth and organ development is controversial.…”

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

“…In general, lateral organs from plant species of different size differ in cell number rather than cell size, as exemplified in the case where big petals of Brassica napus have the same size of cells as small petals of Arabidopsis (Arabidopsis thaliana) do (Mizukami and Fischer, 2000;Mizukami, 2001). Thus, cell number is a primary determinant of organ size of a species, although concomitant and/or subsequent cell expansion amplifies and modifies the effect of cell number, contributing to the final size and shape of lateral organs (Tsukaya, 2005;Cho et al, 2007).…”