中国橡胶树疫霉种的研究

疫病是我国植胶区的主要病害。近年来,作者从云南西双版纳和广东海南岛的橡胶树和胶园土共分离出57株疫霉菌种。通过分类研究,共鉴定出4个种:恶疫霉 Phytophthoracactorum(Leb.＆ Cohn)Schroeter,辣椒疫霉 P.capsici Leoman,柑桔褐腐疫霉 P.citrophthora(Sm.＆ Sm.)Leonian,和棕榈疫霉 P.palmivora(Butl.)Butler。其中辣椒疫霉是首次在橡胶树上发现。我国橡胶树疫霉的种群结构与东南亚和南亚的有所不同,除棕榈疫霉外,其余3种在东南亚和南亚均未发现。而东南亚常见种:簇囊疫霉(P.botryosa)、橡胶疫霉(P.heveae)和蜜色疫霉(P.meadii),在我国却迄今尚未发现或有待证实。以前报道分离自胶园土壤中的芋疫霉(P.colocasiae),可能系柑桔褐腐疫霉之误。绝大多数分离物经配对培养均可产生性器官:辣椒疫霉的A~1交配型和A~2交配型大致相等;柑桔褐腐疫霉和棕榈疫霉的A~2交配型则明显多于A~1交配型。

STUDIES ON PHYTOPHTORA SPECIES FROM RUBBERTREE (HEVEA BRASILIENSIS) IN CHINA

Phytophthora blight is the major disease in rubbertree plantations in China. A total of 57 isolates from diseased leaves, bark, fruit, twig of rubbertree and from infested soil in the plantations were obtained from Xishuangbanna of Yunnan Province and Hainan Island of Guangdong Province. These isolates were identified as P. cactorum, P. capsici, P. citrophthora and P. palmivora, basing upon the morphology of sporangia, sporangial caducity, pedicel length, type of anheridia and physiological characteristics such as mycelial growth rate, protein patters of electrophoresis etc. Rubbertree is a new host for P. capsici.The population structure of Phytophthora in rubberee plantations in China is quite different from that of Southeast and South Asia. Except P. palmivora, all other three species are not found in Southeast and South Asia, while the species occurring on rubbertree in Southeast and South Asia, i.e. P. botryosa, P. heveae and P. meadii, are not found in China.The morphology of Phytophthora palmivora in China is similar to that of phytophthoros in Southeast and South Asia. P. capsici and P. citrophthora have no significant differences in morphology of sporangia and oogonia. The only difference between these two species is the sporangia caducity, the former posses diciduous sporangia with long pedicel, but the latter is not deciduous.The electrophoretic protein patterns of four species show the distinct interspecific differences and the basic intraspecific similarities. The result supports the morphological taxonomy. However, all the four Species can easily utilize starch as a sole carbon source, and have no distinct difference in starch utilization.Most isolates can form sex organs when paired with an opposite strain. Both A~1 and A~2 mating types are detected in these two districts. The proportion of A~1 and A~2 mating type of Phytophthora capsici is more or less the same. As for P. citrophthora and P. palmivora, A~2 mating type is predominant.