渐渗现象

Beijingensis under three droughttreatments, normal, moderate and severe stresses. The results showed:(1) the canker disease ofboth cultivars was serious gradually with increased drought;(2) the bark tissue cells sufferedplasmolysis, more evident with the severity of drought stress;(3) under the drought andinoculation with B. dothidea, cells of two cultivars damaged at different degree, mailyrepresented in the changes of organelles, such as chloroplast swollen and distorted, number ofmitochondria increased and membrane system indistinct; then organelles suffered furtherdamagement with inoculation time, thinned mitochondrias stroma, decreased cristae, crumpledand partly broken membrane of chloroplasts with stroma exosmosis. At last, the chloroplastspartly disorganized;(4) the hyphae growed mainly intercellular in resistant cultivar and notonly intercellular but also intracellular in susceptible cultivar, which directly caused thenecrosis of cells;(5) under the severe drought, the damage of cells enhanced the infection ofpathogen and drought and pathogen stressed together and promoted the disease development;the damage from pathogen on cells was more serious than that from drought.

结果显示：(1)随着干旱胁迫程度的增加，2种杨树溃疡病害发生渐趋严重；(2)干旱胁迫下，杨树树皮组织细胞发生质壁分离，并随胁迫程度的增加而严重；(3)干旱胁迫下接种病原菌，2种杨树细胞发生不同程度的损伤，主要表现为细胞器发生较大变化，如出现叶绿体肿胀变形、线粒体数量增多，质膜模糊不清等现象；随接种时间的延长，细胞器受到进一步损伤，叶绿体被膜折皱，严重时局部破裂，基质外渗，并部分最终解体；(4)毛白杨中的菌丝主要在细胞间隙中穿行，而北京杨的菌丝除在细胞间隙中生长之外，侵入细胞内部也较多，直接导致细胞的解体；(5)干旱胁迫下细胞的损伤促进了病原菌的侵染，干旱和病原菌的双重胁迫加剧了病害的发生程度，并且病原菌侵染对细胞的破坏程度大于水分胁迫。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。