Leaf hydraulic conductance is linked to leaf symmetry in bifacial, amphistomatic leaves of sunflower. (23rd January 2020)

• Record Type: Journal Article
• Authors: Richardson, Freya; Jordan, Gregory J; Brodribb, Timothy J
• Editors: Griffiths, Howard
• Is Part Of: Journal of experimental botany. Volume 71:Number 9(2020)
• Page Start: 2808
• Page End: 2816
• Publication Date: 2020-01-23
• Subjects: Amphistomaty -- hydraulic conductance -- Kleaf -- leaf water potential -- mesophyll -- stomata -- stomatal ratio -- vein density; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/eraa035
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Anatomical asymmetries between the leaf surfaces lead to different hydraulic conductances when transpiration is driven through each surface. These results provide physiological evidence of potential trade-offs associated with amphistomaty. Abstract: The hydraulic implications of stomatal positioning across leaf surfaces and the impact on internal water flow through amphistomatic leaves are not currently well understood. Amphistomaty potentially provides hydraulic efficiencies if the majority of hydraulic resistance in the leaf exists outside the xylem in the mesophyll. Such a scenario would mean that the same xylem network could equally supply a hypostomatic or amphistomatic leaf. Here we examine leaves of Helianthus annuus to determine whether amphistomaty in this species is associated with higher hydraulic efficiency compared with hypostomatic leaves. We identified asymmetry in the positioning of minor veins which were significantly closer to the abaxial than the adaxial leaf surface, combined with lower K leaf when transpiration was driven through the adaxial rather than the abaxial surface. We also identified a degree of coordination in stomatal behaviour driven by leaf hydraulics, where the hydraulic conditions experienced by an individual leaf surface affected the stomatal behaviour on the opposite surface. We found no advantage to amphistomaty based on efficiencies in construction costs of the venous system, represented by vein density:stomatal density, only limited hydraulic independence between leaf surfaces. These results suggest that amphistomaty does not substantially increase whole-leaf hydraulic efficiency.