Visualizing Embolism Propagation in Gas-Injected Leaves
Visualizing Embolism Propagation in Gas-Injected Leaves
复制标题
DOI：
10.1104/pp.18.01284
复制
发表时间：
2019-06-01
期刊：
影响因子：
7.4
通讯作者：
Holbrook, N. Michele
中科院分区：
文献类型：
--
作者：
Hochberg, Uri;Ponomarenko, Alexandre;Holbrook, N. Michele
由于叶片中的木质部被认为是最大的空化风险，可靠和有效的方法来表征叶片木质部的脆弱性是感兴趣的。本文报道了一种用注气法生成叶片木质部脆弱曲线的方法。利用光学透射技术，我们观察了注入正气压的葡萄树（Vitis vinifera）和红橡树（Quercus rubra）叶片中的栓塞传播。这导致了透射光的迅速、逐步减少，与叶片脱水过程中观察到的相同，证实了光学方法检测到气泡，并为空气播种假说提供了见解。在红橡木中，注气产生的木质部vc与实验脱水产生的相似，但在较低的张力（0.4 MPa）下，葡萄藤的电导率损失了50%。在测定VC时，该方法不需要确定木质部张力，从而避免了水势估计中的潜在误差。它也更快（每个VC 1小时）。然而，切断叶柄和施加高压气体会影响空播和VC的生成。我们讨论了由气体注入引起的潜在伪像，并建议将该方法与更标准的程序进行比较，然后再假设该方法适用于给定物种。
Because the xylem in leaves is thought to be at the greatest risk of cavitation, reliable and efficient methods to characterize leaf xylem vulnerability are of interest. We report a method to generate leaf xylem vulnerability curves (VCs) by gas injection. Using optical light transmission, we visualized embolism propagation in grapevine (Vitis vinifera) and red oak (Quercus rubra) leaves injected with positive gas pressure. This resulted in a rapid, stepwise reduction of transmitted light, identical to that observed during leaf dehydration, confirming that the optical method detects gas bubbles and provides insights into the air-seeding hypothesis. In red oak, xylem VCs generated using gas injection were similar to those generated using bench dehydration, but indicated 50% loss of conductivity at lower tension (similar to 0.4 MPa) in grapevine. In determining VC, this method eliminates the need to ascertain xylem tension, thus avoiding potential errors in water potential estimations. It is also much faster (1 h per VC). However, severing the petiole and applying high-pressure gas could affect air-seeding and the generated VC. We discuss potential artifacts arising from gas injection and recommend comparison of this method with a more standard procedure before it is assumed to be suitable for a given species.