【作者】 亢志华；

【导师】 韩正敏；

【作者基本信息】 南京林业大学 ， 微生物学， 2007， 硕士

【摘要】 丝核菌是一类在自然界中广泛存在的真菌,自1851年De Candolle建立丝核菌属(Rhizoctonia)以来,人们对其进行了大量的研究。但由于丝核菌只有结构相似的菌丝,很少产生有性和无性孢子,有性态的诱导极为困难,所以给丝核菌的分类鉴定工作带来了很大的困难。丝核菌能够与兰科植物共生,促进兰科植物生长。但是,丝核菌又是一种广泛分布于土壤和植物根部的植物病原真菌,它可以引起松苗、豆科植物等植物的猝倒病、水稻、小麦纹枯病、马铃薯黑痣病等多种病害。丝核菌究竟是植物病原真菌还是菌根菌的问题一直难以解答,激发了广大研究者的广泛兴趣。本研究收集了11个丝核菌菌株,分别接种到铁皮石斛、马尾松和刺槐上,测定这些菌株与三种苗木之间的相互关系。测定结果将供试菌株分为有促生作用和致病作用两大类;其中有促生作用的菌株是铁皮石斛的菌根真菌。对各丝核菌菌株进行形态学鉴定,并进行菌落形态特征、菌落生长速度、细胞核数目、菌丝融合和有性态诱导等几个方面研究,得出结果如下:1.通过接种测定发现,有促生作用和有致病作用的丝核菌是两类完全不同的丝核菌。其促生和致病特性是由菌株本身的遗传特性所决定,而与寄主植物种类和接种量关系不大。2.对收集到的11个丝核菌菌株进行形态学观察,发现有致病作用与有促生作用的两类菌株,无论是在菌落形态还是菌丝形态上都有很大的不同。有致病作用的丝核菌生长速度快,菌落多以褐色为主,菌丝较粗,分枝多,有多核和双核细胞,以双核细胞居多,易形成菌核;有促生作用的丝核菌生长速度慢,菌落多以白色或无色为主,菌丝细,分枝少,全部为多核细胞,不形成菌核。3.供试丝核菌株中GDB254、MLX102、CLN103、CT301、GH222、GDB181对铁皮石斛、刺槐、马尾松均无致病力,并且还能促进铁皮石斛的生长发育,通过研究接菌铁皮石斛鲜重增长率、叶绿素含量变化、显微观察菌根形态结构,结果表明:接种GDB254、MLX102、CLN103的铁皮石斛鲜重增长率分别比对照增加85%、104%和91%,均达到极显著水平,接种CT301、GH222、GDB181的铁皮石斛鲜重增长率分别比对照增加38%、47%和69%,也达到了显著水平;叶绿素a、b、a+b含量增加分别为:GDB254 76.2%、128%和89.5%,MLX102 84.9%、85.4%和85.1%,CLN103 57.9%、77.8%和63%,CT301 61.2%、54.6%和59.5%,GH222 72.4%、86.7%和76.0%,GDB181 25.9%、36.1%和28.5%;并且显微观察菌根的徒手切片在根被、皮层、中柱细胞中均有菌丝结典型结构。4.供试丝核菌菌株中DHX121、DHX341、LS、HL、GD142对铁皮石斛、马尾松、刺槐均有致病作用,其中GD142的致病力最强,HL次之,DHX121、DHX341、LS致病力稍弱;且三种苗木的发病情况是:铁皮石斛最易感病,刺槐次之,马尾松最不易感病。不同接种量与寄主发病时间有关,接种量大,发病早;接种量小,发病迟。更多还原

【Abstract】 Rhizoctonia is a kind of fungi distributed abroad in the nature. Since 1985 De Candolle established Rhizoctonia genus, researchers have done lots of work in this field. However, the classified and identified work of Rhizoctonias is very difficult, because Rhizoctonias only have similar structured hyphae and no teleomorph and anamorphs spore. Rhizoctonia may be the pathogeny of many plants, or saprophyte in cultivated soil or the mycorrhiza of orchids. The research on the relationship between Rhizoctonias and plants has been paid more attention.This research got 11 strains of Rhizoctonia and inoculated them into the roots of seedlings of the Deudrobium caudidum which were gained by tissue culture, and Pinus massoniana and Robinia pseudoacadiaa which were sterile, in order to study the relationship between the Rhizoctonia and the plants. According to the mensurated result, the Rhizoctonia strains were divided into two groups. They were pathologic group and the non-pathologic group; the non-pathologic group were approved to be the mycorrhiza of D. caudidum, and beneficial to the growth of D. caudidum. According to the research of morphology and physiology, included morphological character of the colony and the hypha, the number of the nuclear of the strains, and anatomosis reaction, the relationship between the Rhizoctonia and the plants and diversity of Rhizoctonia strains had been studied. The main results were as follows:1. According to the research, there were many differences between the pathogenic and non-pathogenic group.The pathogenicity of the different strains have something to do with the characteristic of the strains themselves. The kinds of host and the quantity of inoculation also have some influence on it, but not the most important ones.2. According to the study on morphology and physiology of the 11 strains, it has been found that the differences between the pathogenic and non-pathogenic group were extremely distinct not only on morphologic characteristics of the colonies but also on the characteristics of the hyphae. The strains of pathogenic group grew fast, had brown colony colour, thin colony, more divarications of hyphae, binuclear or multinuclear hyphae, and formed the sclerotium easily. The non-pathogenic strains grew slowly, had white colony colour, thick colony, less divarications of hyphae, multicuclear hyphae, and did not produce any sclerotium.3. The strains of GDB254, MLN102, CLN103, CT301, GH222, GDB181 were non- pathologic for D. caudidum, P. massoniana and R. pseuudoacadiaa, and were the mycorrhizal fungi of D.caudidum. By testing the increasing rate of fresh weight of the seedlings, the rate of chloropphll a,b content, and observing the microstructure of the roots of D. caudidum, it was found that the average fresh weight of seedlings which were inoculated with the six strains were higher than those of constrastive seedlings after 65 days, respectively were 85%, 104%, 91% 38%, 47% and 69%. All these results were extremely significant (α=0.01) and significant (α=0.05). Chloropphll a, b content of seedlings were also higher than those of contrastive seedlings, those were GDB254 76.2%, 128% and 89.5%, MLX102 84.9%, 85.4% and 85.1%, CLN103 57.9%, 77.8% and 63%,CT301 61.2%, 54.6% and 59.5%, GH222 72.4%, 86.7% and 76.0%, GDB181 25.9%, 36.1% and 28.5% respectively. Through observation on the microstructure of mycorrhiza, we found that there were many pelotons in cortical and vascular tissue. So it was confirmed that the relationship of symbiosis was already formed, the growth and chloropphll a, b content of D. candidum were promoted by the mycorrhizal fungi.4. According to the pathogenic test, it had been found that the strains of DHX121, DHX341, LS, HL and GD142 were all possessed of pathogenic function. Among them, the pathogenicity of strain GD142 was the most serious one, the strain HL was the mild and the strains DHX121, DHX341 and LS were the least. Among the three tested plants, D. candidum could be infected easily, R. pseudoacaciaa is the next one, and P. massoniana is the hardest one to be infected. And it also showed that the more quantity to be inoculated, the quicker to be infected.更多还原