Haverroth Eduardo J, Oliveira Leonardo A, Andrade Moab T, Taggart Matthew, McAdam Scott A M, Zsögön Agustin, Thompson Andrew J, Martins Samuel C V, Cardoso Amanda A
Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Plant Cell Environ. 2023 Nov;46(11):3229-3241. doi: 10.1111/pce.14676. Epub 2023 Aug 1.
Drought resistance is essential for plant production under water-limiting environments. Abscisic acid (ABA) plays a critical role in stomata but its impact on hydraulic function beyond the stomata is far less studied. We selected genotypes differing in their ability to accumulate ABA to investigate its role in drought-induced dysfunction. All genotypes exhibited similar leaf and stem embolism resistance regardless of differences in ABA levels. Their leaf hydraulic resistance was also similar. Differences were only observed between the two extreme genotypes: sitiens (sit; a strong ABA-deficient mutant) and sp12 (a transgenic line that constitutively overaccumulates ABA), where the water potential inducing 50% embolism was 0.25 MPa lower in sp12 than in sit. Maximum stomatal and minimum leaf conductances were considerably lower in plants with higher ABA (wild type [WT] and sp12) than in ABA-deficient mutants. Variations in gas exchange across genotypes were associated with ABA levels and differences in stomatal density and size. The lower water loss in plants with higher ABA meant that lethal water potentials associated with embolism occurred later during drought in sp12 plants, followed by WT, and then by the ABA-deficient mutants. Therefore, the primary pathway by which ABA enhances drought resistance is via declines in water loss, which delays dehydration and hydraulic dysfunction.
在水分受限的环境下，抗旱性对于植物生产至关重要。脱落酸（ABA）在气孔调节中起关键作用，但其对气孔以外的水力功能的影响却鲜有研究。我们选择了积累ABA能力不同的基因型来研究其在干旱诱导功能障碍中的作用。无论ABA水平存在差异，所有基因型均表现出相似的叶片和茎干抗栓塞能力。它们的叶片水力阻力也相似。仅在两个极端基因型之间观察到差异：sitiens（sit；一种严重的ABA缺陷突变体）和sp12（一个组成型过量积累ABA的转基因系），其中诱导50%栓塞的水势在sp12中比sit低0.25MPa。ABA含量较高的植株（野生型[WT]和sp12）的最大气孔导度和最小叶片导度明显低于ABA缺陷型突变体。不同基因型间气体交换的变化与ABA水平以及气孔密度和大小的差异有关。ABA含量较高的植株水分损失较低，这意味着与栓塞相关的致死水势在干旱期间在sp12植株中出现得较晚，其次是WT，然后是ABA缺陷型突变体。因此，ABA增强抗旱性的主要途径是通过减少水分损失，从而延迟脱水和水力功能障碍。
