卡特兰与丝核菌共培养体系的建立及卡特兰菌根显微结构的研究

SYMBIOSIS BETWEEN CATTLEYA SP. AND RHIZOCTONIA SP. AND MYCORRHIZAL MICROSTRUCTURE OF CATTLEYA SP.

用3个分离自野生卡特兰的丝核菌菌株接种卡特兰组培幼苗,对幼苗生长有不同程度的促进作用,处理苗的鲜重增长率(%)分别是67.5、67.3和62.4,而不接菌的对照仅为49.5,其中KW214菌株处理苗与对照差异达显著水平(α=0.05)。接菌处理后植株的N、P、K含量没有明显增加。在三个接菌处理苗的营养根中均分离获得了原接种真菌,并观察了接种KW214菌株的卡特兰营养根。真菌先侵入根被组织,经通道细胞最后侵染皮层组织细胞,并通过菌丝穿越细胞壁不断地向内延伸扩展。菌丝在皮层组织细胞内形成大量着色较深形状不规则的菌丝结等兰科菌根典型结构,菌丝结在皮层组织中分布不均,多出现在靠外侧的几层皮层细胞内,在被侵染的细胞中,菌丝结常出现在细胞核附近。菌丝结、针状晶体和细胞核在形态和着色反应上有明显区别。菌丝结和细胞核常常相互靠近。从生物量增长、显微结构、重分离接种菌株等三个方面获得的证据表明,已成功建立了卡特兰组培幼苗和丝核菌KW214的共培养体系。

Three fungus strains that are all isolated from wild Cattleya sp. and preliminarily identified as Rhizoctonia sp. were inoculated to tissue culture seedlings of Cattleya sp.. After inoculation the growth of seedlings was promoted at different level. The average increment (%) of weight of seedlings treated with these three strains are 67.5, 67.3 and 62.4 respectively, and the control is just 49.5. Average increment of fresh weight of the seedlings inoculated with strain KW214 is more significantly higher than that of control (? 0.05). Content of N, P and K in the treated seedlings did not increase notably. The primal strains were all re-isolated from 3 treated seedlings. The microstructure of nutritive root of the seedlings inoculated with KW214 was observed. The fungi infected the velamen at first, and then cortical cell through passage cell. The hyphae penetrated through the wall of cortical cells and continuously spread inward. The hyphae formed a lot of pelotons, a typical orchidaceous mycorrhiza structure, which are irregular and deep-coloured in the cortical cells. The pelotons are distributed irregularly in cortex, mainly outer several cortical cells. In infected cortical cell, pelotons often occur nearby nucleus. Peloton, crystal and nucleus are easily recognized. It seems that the symbiosis relationship between Cattleya sp. and Rhizoctonia sp. (KW214) has been established.