The origin of the diversity of leaf venation pattern

Abstract

The leaf venation pattern of plants shows remarkable diversity and species-specificity. However, the mechanism underlying the pattern formation and pattern diversity remains unclear. We developed a mathematical model that is based on the positive feedback regulation between plant hormone auxin and its efflux carrier. This system can generate auxin flow pathways by self-organization from an almost homogeneous state. This result explains a well-known experimental phenomenon referred as to "polar auxin transport." The model can produce diverse leaf venation patterns with spatial regularity under similar conditions to those of leaf development, that is, in the presence of leaf expansion and auxin sink. Final venation patterns are strikingly affected by leaf shape and leaf expansion. These results indicate that the positive feedback regulation between auxin and its efflux carrier is a central dynamic in leaf venation pattern formation. The diversity of leaf venation patterns in plant species is probably due to the differences of leaf shape and leaf expansion pattern.

Leaf palmate venation and vascular redundancy confer tolerance of hydraulic disruption

“…The ancestral flowering plants most likely had pinnate venation, and evolutionary shifts to palmate venation, and reversals, appear in numerous families (e.g., 10, 60-64), with additional transitions obscured by extinctions (56,65). Theoretically, the shifts may arise due to mutation of one or a few genes that alter the sequence or timing of leaf form development (10,66,67). However, within lineages, venation type tends to be phylogenetically conserved (e.g., 10, 61-64), suggesting that transitions are rare relative to speciation and extinction events (68).…”

Evolving Reaction-Diffusion Systems on GPU

“…Another envisaged extension is to impose mass and energy conservation constraints to reduce the search space to resource-saving and physically plausible solutions. In order to evolve vein and leaf patterns [7,18], the active transport of chemicals is desirable, beyond passive diffusion. In order to improve convergence speed and escape more easily from local optima, another research topic would be the adaptation of more sophisticated algorithms, such as CMA-ES [12,19] or the nested evolution algorithm from [14], to the evolution of reaction networks in the RDS context.…”

“…Other well-known RD patterns include circles and spirals in the Belousov-Zhabotinsky reaction, self-replicating spots in the Gray-Scott system [10,23], and diverse patterns on the surface of sea shells [18]. More complex morphogenetic processes such as the formation of net patterns in leafs or veins [7], the formation of insect eyes and various body parts, are only partially explained by reaction-diffusion processes, nevertheless RD remains an important component of morphogenesis in general.…”

Genetic control of leaf-blade morphogenesis by the INSECATUS gene in Pisum sativum

“…In the compound leaf-blade bearing plants such as pea, the meristematic cells (meristem) of leaf-blade primordium are expected to allocate procambium for vascular tissue of petiole and rachis in leaf blade and for veins in leaflets within latter. Since the secondary veins in the pea leaflets are directed apically, the growth of midvein and origin from it of about 10 pairs of secondary veins must be acropetal; or the midvein polarity in leaflets is from petiolule outwards to the tip (Dengler and Tsukaya 2001;Burton 2004;Fujita and Mochizuki 2006). The midvein procambium is known to be patterned very early in the simple leaf ontogeny (Hageman and Gleissberg 1996;Dengler and Tsukaya 2001;Scarpella and Meijer 2004;Floyd and Bowman 2006;White 2006).…”