Qie Ya-Dong, Zhang Qi-Wei, McAdam Scott A M, Cao Kun-Fang
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China.
Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, China.
Plant Divers. 2024 Feb 8;46(3):395-405. doi: 10.1016/j.pld.2024.02.003. eCollection 2024 May.
Stomatal regulation is critical for mangroves to survive in the hyper-saline intertidal zone where water stress is severe and water availability is highly fluctuant. However, very little is known about the stomatal sensitivity to vapour pressure deficit (VPD) in mangroves, and its co-ordination with stomatal morphology and leaf hydraulic traits. We measured the stomatal response to a step increase in VPD , stomatal anatomy, leaf hydraulic vulnerability and pressure-volume traits in nine true mangrove species of five families and collected the data of genome size. We aimed to answer two questions: (1) Does stomatal morphology influence stomatal dynamics in response to a high VPD in mangroves? with a consideration of possible influence of genome size on stomatal morphology; and (2) do leaf hydraulic traits influence stomatal sensitivity to VPD in mangroves? We found that the stomata of mangrove plants were highly sensitive to a step rise in VPD and the stomatal responses were directly affected by stomatal anatomy and hydraulic traits. Smaller, denser stomata was correlated with faster stomatal closure at high VPD across the species of Rhizophoraceae, and stomata size negatively and vein density positively correlated with genome size. Less negative leaf osmotic pressure at the full turgor (π) was related to higher operating steady-state stomatal conductance (); and a higher leaf capacitance () and more embolism resistant leaf xylem were associated with slower stomatal responses to an increase in VPD. In addition, stomatal responsiveness to VPD was indirectly affected by leaf morphological traits, which were affected by site salinity and consequently leaf water status. Our results demonstrate that mangroves display a unique relationship between genome size, stomatal size and vein packing, and that stomatal responsiveness to VPD is regulated by leaf hydraulic traits and stomatal morphology. Our work provides a quantitative framework to better understand of stomatal regulation in mangroves in an environment with high salinity and dynamic water availability.
气孔调节对于红树林在高盐潮间带生存至关重要，在该区域水分胁迫严重且水分可利用性波动极大。然而，关于红树林气孔对蒸汽压亏缺（VPD）的敏感性及其与气孔形态和叶片水力特征的协调性，我们所知甚少。我们测量了五个科的九种真红树植物气孔对VPD阶跃增加的响应、气孔解剖结构、叶片水力脆弱性和压力-容积特征，并收集了基因组大小的数据。我们旨在回答两个问题：（1）考虑到基因组大小对气孔形态的可能影响，气孔形态是否会影响红树林对高VPD的气孔动态响应？（2）叶片水力特征是否会影响红树林气孔对VPD的敏感性？我们发现，红树林植物的气孔对VPD的阶跃升高高度敏感，气孔响应直接受气孔解剖结构和水力特征影响。在红树科物种中，更小、更密集的气孔与高VPD下更快的气孔关闭相关，气孔大小与基因组大小呈负相关，叶脉密度与基因组大小呈正相关。完全膨压下较低的叶片渗透势（π）与较高的运行稳态气孔导度（）相关；较高的叶电容（）和更抗栓塞的叶片木质部与对VPD增加的较慢气孔响应相关。此外，气孔对VPD的响应性间接受到叶片形态特征的影响，而叶片形态特征受生境盐度影响，进而受叶片水分状况影响。我们的结果表明，红树林在基因组大小、气孔大小和叶脉排列之间呈现出独特的关系，并且气孔对VPD的响应性受叶片水力特征和气孔形态调节。我们的工作提供了一个定量框架，以更好地理解高盐度和动态水分可利用性环境下红树林的气孔调节。
