南方根结线虫侵染黄瓜幼根组织病理学观察

Histopathological structure of cucumber radicle infected by root-knot nematode

人工接种南方根结线虫（Meloidogyn incognita）,观察不同侵染时间黄瓜根部组织的病理特征。结果显示：接种后6 d的根尖分生区、伸长区出现膨大、对称的根结,根中心的原形成层细胞分化出巨型细胞;10 d在根毛区及以上部位出现既有对称又有偏于一侧的根结,周围有原生木质部导管出现,根结中巨型细胞阻断了导管;16 d次生维管组织提早出现;20～30 d导管纵向排列无序,形状扭曲,皮层中有新维管组织产生。总之,随侵染时间的延长,根部受害部位逐渐由内皮层扩展至皮层,根结逐渐由巨型细胞、提早形成的次生维管组织以及皮层中的新维管组织共同形成;导管逐渐受阻,排列扭曲无序。

Pathological features of a cucumber radicle tissue inoculated with root-knot nematodes（RKN, Meloidogyn incognita）were observed on different days. Six days after inoculation, the cucumber root tip was slightly swollen and symmetrical root-knots were observed at the meristematic and elongation zones. Giant cells were differentiated by previous cambium ceils in the center of the root; 10days after inoculation, symmetrical and secondary root-knots were observed at the root hair and upper zones. Vessels were separated by giant cells, around which protoxylem vessels were observed; 16days after inoculation, hypo-vascular tissue appeared earlier than normal; 20- 30 days after inoculation, the vertical arrangement of vessels was disordered, shape was distorted and a new vascular tissue appeared in the cortex. With time after inoculation with RKN, the injured parts of the root tissue developed from endoderm to cortex; the root-knots were gradually formed by giant cells, earlier appeared hypo-vascular tissues and new vascular tissues in the cortex; vessels were suffocated gradually until they were disordered and distorted in shape.