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Abstract Plants differ widely in how soil drying affects stomatal conductance (gs) and leaf water potential (ψleaf), and in the underlying physiological controls. Efforts to breed crops for drought resilience would benefit from a better understanding of these mechanisms and their diversity. We grew 12 diverse genotypes of common bean (Phaseolus vulgarisL.) and four of tepary bean (P. acutifolius;a highly drought resilient species) in the field under irrigation and post‐flowering drought, and quantified responses ofgsandψleaf, and their controls (soil water potential [ψsoil], evaporative demand [Δw] and plant hydraulic conductance [K]). We hypothesised that (i) common beans would be more “isohydric” (i.e., exhibit strong stomatal closure in drought, minimisingψleafdecline) than tepary beans, and that genotypes with largerψleafdecline (more “anisohydric”) would exhibit (ii) smaller increases in Δw, due to less suppression of evaporative cooling by stomatal closure and hence less canopy warming, but (iii) largerKdeclines due toψleafdecline. Contrary to our hypotheses, we found that half of the common bean genotypes were similarly anisohydric to most tepary beans; canopy temperature was cooler in isohydric genotypes leading to smaller increases in Δwin drought; and that stomatal closure andKdecline were similar in isohydric and anisohydric genotypes.gsandψleafwere virtually insensitive to drought in one tepary genotype (G40068). Our results highlight the potential importance of non‐stomatal mechanisms for leaf cooling, and the variability in drought resilience traits among closely related crop legumes.
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Aquaporin regulation in roots controls plant hydraulic conductance, stomatal conductance, and leaf water potential in Pinus radiata under water stress
Abstract Stomatal regulation is crucial for forest species performance and survival on drought‐prone sites. We investigated the regulation of root and shoot hydraulics in threePinus radiataclones exposed to drought stress and its coordination with stomatal conductance (gs) and leaf water potential (Ψleaf). All clones experienced a substantial decrease in root‐specific root hydraulic conductance (Kroot‐r) in response to the water stress, but leaf‐specific shoot hydraulic conductance (Kshoot‐l) did not change in any of the clones. The reduction inKroot‐rcaused a decrease in leaf‐specific whole‐plant hydraulic conductance (Kplant‐l). Among clones, the larger the decrease inKplant‐l, the more stomata closed in response to drought. Rewatering resulted in a quick recovery ofKroot‐randgs. Our results demonstrated that the reduction inKplant‐l, attributed to a down regulation of aquaporin activity in roots, was linked to the isohydric stomatal behaviour, resulting in a nearly constant Ψleafas water stress started. We concluded that higherKplant‐lis associated with water stress resistance by sustaining a less negative Ψleafand delaying stomatal closure.
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- Award ID(s):
- 1754893
- PAR ID:
- 10079887
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Plant, Cell & Environment
- Volume:
- 42
- Issue:
- 2
- ISSN:
- 0140-7791
- Page Range / eLocation ID:
- p. 717-729
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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