Pathogenetic and physiological mechanisms of poplar ice nucleation active bacterial canker

Using the methods introduced by Bier, X.H., Buchinock, Wang Jing-wen, Shi Riheet al., different varieties of poplar (poplar-MeixQing, Poplar-A100, Poplar-Xiaohe14et al.) were inoculated with poplar ice nucleation active (INA) bacteria respectively in 1997–1999. The water content, relative turgidity, lignin content, phenylalanine ammonialyase (PAL) activity, electrolyte effusion rate, and inorganic element content of poplar bark were measured before and after inoculating. The results showed that after the poplar trees were inoculated with INA bacteria, the moisture content of bark decreased but relative turgidity increased, electrolyte effusion rate increased and had a peak at temperatures of −4 and 5°C, lignin content increased and positively correlated with poplars’ disease-resistance and the plenylalanine ammonialyase activity increased and also showed a significant positive correlation with poplars' disease-resistance. For the contents of inorganic element, Cu and Fe decreased but K and Zn increased obviously, while Mn, Ca and Mg changed little.