Stable stomatal number per minor vein length indicates the coordination between leaf water supply and demand in three leguminous species

Wan-Li Zhao,Jiao-Lin Zhang,Pei-Li Fu,Kun-Fang Cao,Zafar Siddiq

doi:10.1038/s41598-017-02448-y

Abstract

The coordination between minor vein density (MVD) and stomatal density (SD) has been found in many plants. However, we still know little about the influence of leaf node on this correlation relationship. Here, we devised the new functional trait ‘stomatal number per minor vein length’ (SV). By measuring leaflet area (LA), MVD, SD, and SV, we demonstrated the significance of this functional trait in Arachis hypogaea (peanut) grown under different light regimes and in sun leaves of Dalbergia odorifera and Desmodium renifolium. We found that SV did not change significantly with leaflet node or with LA within each light treatment, while shading caused a significant decrease in SV. The positive correlation between SD and MVD was found in peanut under each light regime. Sun leaves of D. odorifera and D. renifolium also had stable SV along the leaflet node, with a positive correlation between MVD and SD. We conclude that under a certain light regime, a stable SV similar to the positive correlation between MVD and SD can also indicate the coordination between leaf water supply and demand. Our findings highlight the significance of SV and provide new insight into the coordination between stomatal number and minor vein length.

Highlights

Leaf veins provide a pathway of low resistance for water flow through the mesophyll tissue to evaporative surfaces near the stomata where it is exchanged for CO21, 2
We propose a new functional trait: the stomatal number per minor vein length (SV, no. mm−1), which is calculated by dividing stomatal density (SD) by minor vein density (MVD)
Peanut and the selected two species belong to Leguminosae, representing an herb with compound leaves, a tree with compound leaves (D. odorifera), and a shrub with a unifoliolate leaf (D. renifolium). Both leaflet area (LA) and MVD increased with leaflet node from 1st to 4th within each of the three light regimes, while no significant changes with leaflet node from 5th to 8th (Fig. 1a,c)

Summary

Introduction

Leaf veins provide a pathway of low resistance for water flow through the mesophyll tissue to evaporative surfaces near the stomata where it is exchanged for CO21, 2. Trees[1], SV is calculated by dividing SD by MVD and has little relation to the distance from the vein to the stomata Both SV and the slope of the linear regression between SD and MVD (SD = b + a × MVD) can indicate the proportional change in stomatal number with minor vein length, they have different biological significance and could have the same numerical value only when the intercept of the linear regression is zero[19]. Such sun exposed leaves can have greater MVD and SD13, 20, 22 These studies have documented the effect of shading on MVD and SD, little is known about the influence of extreme low light on changes in their coordination. Many studies have reported the relationship between leaf area and SD and MVD1, 10, 11, 13, 26, yet little is known about the relationship between leaf area and SV

Methods

Results

Conclusion