The role of elastic stresses on leaf venation morphogenesis

TL;DR

This paper investigates how elastic stresses between leaf tissues influence venation pattern formation, proposing a mechanical instability model that explains hierarchical vein loops better than traditional hormone-based hypotheses.

Contribution

It introduces a mechanical instability model driven by elastic mismatch to explain complex venation patterns, including vein loops, challenging the solely hormone-driven canalization hypothesis.

Findings

Model reproduces hierarchical vein patterns with loops.

Numerical results match real venation statistical properties.

Mechanical stresses likely influence leaf venation development.

Abstract

We explore the possible role of elastic mismatch between epidermis and mesophyll as a driving force for the development of leaf venation. The current prevalent 'canalization' hypothesis for the formation of veins claims that the transport of the hormone auxin out of the leaves triggers cell differentiation to form veins. Although there is evidence that auxin plays a fundamental role in vein formation, the simple canalization mechanism may not be enough to explain some features observed in the vascular system of leaves, in particular, the abundance of vein loops. We present a model based on the existence of mechanical instabilities that leads very naturally to hierarchical patterns with a large number of closed loops. When applied to the structure of high order veins, the numerical results show the same qualitative features as actual venation patterns and, furthermore, have the same statistical properties. We argue that the agreement between actual and simulated patterns provides strong evidence for the role of mechanical effects on venation development.