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Neither xylem collapse, cavitation, or changing leaf conductance drive stomatal closure in wheat
Author(s) -
Corso Déborah,
Delzon Sylvain,
Lamarque Laurent J.,
Cochard Hervé,
TorresRuiz José M.,
King Andrew,
Brodribb Timothy
Publication year - 2020
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13722
Subject(s) - xylem , turgor pressure , stomatal conductance , transpiration , cavitation , dehydration , biology , conductance , hydraulic conductivity , agronomy , botany , horticulture , photosynthesis , soil water , ecology , biochemistry , physics , mathematics , combinatorics , mechanics
Identifying the drivers of stomatal closure and leaf damage during stress in grasses is a critical prerequisite for understanding crop resilience. Here, we investigated whether changes in stomatal conductance ( g s ) during dehydration were associated with changes in leaf hydraulic conductance ( K leaf ), xylem cavitation, xylem collapse, and leaf cell turgor in wheat ( Triticum aestivum ). During soil dehydration, the decline of g s was concomitant with declining K leaf under mild water stress. This early decline of leaf hydraulic conductance was not driven by cavitation, as the first cavitation events in leaf and stem were detected well after K leaf had declined. Xylem vessel deformation could only account for <5% of the observed decline in leaf hydraulic conductance during dehydration. Thus, we concluded that changes in the hydraulic conductance of tissues outside the xylem were responsible for the majority of K leaf decline during leaf dehydration in wheat. However, the contribution of leaf resistance to whole plant resistance was less than other tissues (<35% of whole plant resistance), and this proportion remained constant as plants dehydrated, indicating that K leaf decline during water stress was not a major driver of stomatal closure.