Buckley Thomas N, Magney Troy S, Berny Mier Y Teran Jorge C, Mills Colleen, Palkovic Antonia, Parker Travis A, Pierce Marshall A, Wadhwani Yasmin, Wong Christopher Y S, Gepts Paul, Gilbert Matthew E
Department of Plant Sciences, University of California, Davis, California, USA.
Department of Agriculture, Plant Science Faculty, Ventura College, Ventura, California, USA.
Plant Cell Environ. 2025 Jan;48(1):51-64. doi: 10.1111/pce.15106. Epub 2024 Sep 4.
Plants differ widely in how soil drying affects stomatal conductance (g) and leaf water potential (ψ), 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 vulgaris L.) and four of tepary bean (P. acutifolius; a highly drought resilient species) in the field under irrigation and post-flowering drought, and quantified responses of g and ψ, and their controls (soil water potential [ψ], 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, minimising ψ decline) than tepary beans, and that genotypes with larger ψ decline (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) larger K declines due to ψ decline. 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 Δw in drought; and that stomatal closure and K decline were similar in isohydric and anisohydric genotypes. g and ψ were 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.
不同植物在土壤干燥对气孔导度（g）和叶片水势（ψ）的影响以及潜在生理调控方面存在很大差异。培育抗旱作物的工作将受益于对这些机制及其多样性的更好理解。我们在灌溉和花后干旱条件下，在田间种植了12种不同基因型的普通菜豆（Phaseolus vulgaris L.）和4种 tepary 豆（P. acutifolius；一种高度抗旱的物种），并对 g 和 ψ 的响应及其调控因素（土壤水势[ψ]、蒸发需求[Δw]和植物水力导度[K]）进行了量化。我们假设：（i）普通菜豆比 tepary 豆更“等水”（即干旱时气孔强烈关闭，使 ψ 下降最小化），并且 ψ 下降较大（更“非等水”）的基因型将表现出（ii）Δw 的增加较小，因为气孔关闭对蒸发冷却的抑制较少，因此冠层升温较小，但（iii）由于 ψ 下降，K 的下降较大。与我们的假设相反，我们发现一半的普通菜豆基因型与大多数 tepary 豆同样非等水；等水基因型的冠层温度较低，导致干旱时 Δw 的增加较小；并且等水和非等水基因型的气孔关闭和 K 下降相似。在一种 tepary 豆基因型（G40068）中，g 和 ψ 对干旱几乎不敏感。我们的结果突出了非气孔机制对叶片冷却的潜在重要性，以及密切相关的豆类作物抗旱性状的变异性。
