### Research progress on responses of xylem of woody plants to frost-thaw embolism

Zhi-Min LI1,Chuan-Kuan WANG

• Received:2019-04-07 Revised:2019-09-04 Online:2019-09-30
• Contact: Chuan-Kuan WANG

Abstract: Abstract The freeze-thaw induced embolism commonly occurs in the woody plant in mid- and high-latitude regions.The resistance capacity to freeze-thaw embolism of woody plants in cold environments is critical for their growth and successful survival through winter, which directly determines their distribution. During freeze-thaw cycles, the freeze-thaw embolism of vessels is induced by the bubbles that are from dissolved frozen water because of the low solubility of ice. The resistance capacity to freeze-thaw embolism varies with plants with different ana-tomical structures. Plants can also reduce potential damages of freeze-thaw embolism through adjusting the xy-lem positive pressure by refilling embolism and metabolism, and/or increasing the sap solute contents to avoid the stress. Compared to drought induced embolism, however, few studies have been conducted on freeze-thaw embolism, and the underlying mechanisms of plant responses and regulation are poorly understood. In this pa-per, we first reviewed the process of formation and repair of freeze-thaw embolism of xylem, including the strategies of escaping freezing, tolerance, and repairing freeze-thaw cavitation. Then we summarized physio-logical characteristics of plant resistance to low-temperature stress, influencing factors, and evaluating criteria, based on which we discussed the multiple trade-offs between low-temperature resistance, drought resistance, and hydraulic efficiency. Finally, we proposed five priorities in this field: (1) the threshold of freezing temper-ature for different plants; (2) the vulnerability segmentation of frost-induced embolism; (3) the relationships between freeze-thaw cavitation repair and metabolism exhaustion; (4) the potential trade-offs between low-temperature resistance, drought resistance and hydraulic efficiency; and (5) integration of the traits of freeze-thaw embolism resistance into the economic spectrum of plants.