Du Qingjie, Jiao Xiaocong, Song Xiaoming, Zhang Jiayu, Bai Ping, Ding Juping, Li Jianming
College of Horticulture, Northwest A&F University, Yangling, China.
College of Horticulture, Henan Agricultural University, Zhengzhou, China.
Front Plant Sci. 2020 Jun 5;11:758. doi: 10.3389/fpls.2020.00758. eCollection 2020.
Vapor pressure deficit (VPD) is the driver of water movement in plants. However, little is known about how anatomical adaptations determine the acclimation of plant water dynamics to elevated VPD, especially at the whole plant level. Here, we examined the responses of transpiration, stomatal conductance (g), hydraulic partitioning, and anatomical traits in two tomato cultivars (Jinpeng and Zhongza) to long-term high (2.2-2.6 kPa) and low (1.1-1.5 kPa) VPD. Compared to plants growing under low VPD, no variation in g was found for Jinpeng under high VPD conditions; however, high VPD induced an increase in whole plant hydraulic conductance (K), which was responsible for the maintenance of high transpiration. In contrast, transpiration was not influenced by high VPD in Zhongza, which was primarily attributed to a coordinated decline in g and K. The changes in g were closely related to stomatal density and size. Furthermore, high VPD altered hydraulic partitioning among the leaf, stem, and root for both cultivars via adjustments in anatomy. The increase in lumen area of vessels in veins and large roots in Jinpeng under high VPD conditions improved water transport efficiency in the leaf and root, thus resulting in a high K. However, the decreased K for Zhongza under high VPD was the result of a decline of water transport efficiency in the leaf that was caused by a reduction in vein density. Overall, we concluded that the tradeoff in anatomical acclimations among plant tissues results in different water relations in plants under high VPD conditions.
蒸汽压亏缺（VPD）是植物中水分移动的驱动力。然而，关于解剖学适应性如何决定植物水分动态对升高的VPD的适应，尤其是在整株植物水平上，人们知之甚少。在这里，我们研究了两个番茄品种（金鹏和中杂）的蒸腾作用、气孔导度（g）、水力分配和解剖学特征对长期高（2.2 - 2.6 kPa）和低（1.1 - 1.5 kPa）VPD的响应。与在低VPD条件下生长的植物相比，金鹏在高VPD条件下g没有变化；然而，高VPD诱导了整株植物水力导度（K）的增加，这有助于维持高蒸腾作用。相比之下，中杂的蒸腾作用不受高VPD的影响，这主要归因于g和K的协同下降。g的变化与气孔密度和大小密切相关。此外，高VPD通过解剖学调整改变了两个品种叶片、茎和根之间的水力分配。在高VPD条件下，金鹏叶脉和大根中导管腔面积的增加提高了叶片和根中的水分运输效率，从而导致高K。然而，中杂在高VPD条件下K的降低是由于叶脉密度降低导致叶片水分运输效率下降的结果。总体而言，我们得出结论，植物组织间解剖学适应的权衡导致了高VPD条件下植物不同的水分关系。
