Histopathological changes of Cotinus coggygria inoculated with Venicillium dahliae were observed by using paraffin sections and optical microscope photography. The results showed that the different parts of C. coggygria had different infection levels, with leaves the highest (18.83％), and branches the lowest (6. 72％ ). After inoculation, the hyphae initially invaded the elongation zone and mature zone of roots, and then appeared in the intercelluar space cortex parenchyma cells within 1 - 3 cm of the root tip, and further went into vessels of the roots, then reached leaves through the vessels of stems and branches finally. V. dahliae mainly occurred in vessels of xylem in the form of hyphae, however it did not appear continuously. In order to prevent expansion of the pathogen after infected, wall of the vessel was thickened,inner diameter of the vessel was decreased by accumulating jelly and tylosis generated in the xylem, or even the vessel was totally blocked. When the C. coggygria was infected, the vessel walls, parenchyma cells and cortical cells were thickened, the inclusions of pith, resin canals and secretory cells nearby increased, the jelly appeared in the parenchyma cells and wood rays. Although parts of vessels were blocked with hyphae, jelly and tylosis to different extent, most of the vessels were healthy and were able to function water transport normally. The partial block of vessels sometime caused plants wilt, but the plant managed to maintain almost normal activities.%采用石蜡切片和光学显微摄像的方法,对黄栌接种大丽轮枝菌后的组织病理学变化进行系统观察.接种大丽轮枝菌后黄栌不同组织部位受侵染的程度不同,叶部最高(18.83%),而枝条最低(6.72%).菌丝首先由根的伸长区及成熟区侵入,而后出现在距根尖1～3 cm处的皮层薄壁细胞的间隙,接着进入根部的导管内,最终经茎部及枝条的导管到达叶部.大耐轮枝菌主要以菌丝形态存在于木质部导管内,且在导管中不连续出现.在病菌侵染过程中,受侵染黄栌的导管壁、薄壁细胞、皮层细胞增厚并且木质化,髓部、树脂道及其附近的分泌细胞内含物增加,薄壁细胞及木射线内有胶状物出现,导管内部产生胶状物、侵填体等物质,以此缩小导管内径或将导管堵塞,从而阻止病菌的扩展,但大部分健康的导管仍然可以维持植株正常的水分运输.虽然导管的阻塞具有致萎作用,但不足以影响到正常的生命活动.
展开▼
