Harrison Day Beatrice L, Johnson Kate M, Tonet Vanessa, Bourbia Ibrahim, Blackman Chris J, Brodribb Timothy J
School of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia.
Plant Ecology Research Laboratory, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
Plant Physiol. 2024 Dec 2;196(4):2362-2373. doi: 10.1093/plphys/kiae407.
Understanding xylem embolism spread in roots is essential for predicting the loss of function across root systems during drought. However, the lasting relevance of root embolism to plant recovery depends on whether roots can refill xylem emboli and resume function after rehydration. Using MicroCT and optical and dye staining methods, we investigated embolism repair in rehydrated intact roots of wheat (Triticum aestivum L. 'Krichauff') exposed to a severe water deficit of -3.5 MPa, known to cause approximately 30% total root network embolism in this species. Air emboli in the xylem vessels of intact roots remained clearly observable using MicroCT after overnight rehydration. This result was verified by xylem staining of the root system and optical quantification of emboli, both of which indicated a lack of functional root xylem recovery 60 h following soil re-saturation. The absence of root xylem refilling in wheat has substantial implications for how we understand plant recovery after drought. Our findings suggest that xylem embolism causes irreversible damage to the soil-root hydraulic connection in affected parts of the root network.
了解木质部栓塞在根系中的扩散对于预测干旱期间整个根系功能的丧失至关重要。然而，根系栓塞对植物恢复的持久相关性取决于根系在复水后是否能够重新填充木质部栓塞并恢复功能。我们使用微型计算机断层扫描（MicroCT）以及光学和染料染色方法，研究了暴露于-3.5兆帕严重水分亏缺（已知该水分亏缺会导致该物种约30%的总根网络栓塞）的小麦（Triticum aestivum L. 'Krichauff'）完整根系在复水后的栓塞修复情况。经过一夜复水后，使用MicroCT仍可清晰观察到完整根系木质部导管中的空气栓塞。通过对根系进行木质部染色以及对栓塞进行光学定量分析，验证了这一结果，二者均表明土壤重新饱和60小时后根系木质部功能未恢复。小麦根系木质部无法重新填充对我们理解干旱后植物的恢复具有重要意义。我们的研究结果表明，木质部栓塞会对根网络受影响部分的土壤-根系水力连接造成不可逆转的损害。
