中国橡胶树疫霉种的研究

1982—1988年从海南省10个县21个植胶场和云南省西双版纳、德宏州4个县9个植胶场采集橡胶树地上部的各种疫霉病害的样本,通过分离、提纯,共获得172株疫霉分离菌。经鉴定有以下5种疫霉:柑桔褐腐疫霉(Phytophthora citrophthora)、辣椒疫霉(P.capsici)、密氏疫霉(P.meadii)、寄生疫霉(P.parasitica)和棕榈疫霉(P.palmivora)。其中 P.citrophthora 有91株,占52.8%。其它4种疫霉顺次为45侏,占26.2%,19株,占11.1%,14株,占8.1%;3株,占1.8%。本文对这5种疫霉分别作了种的描述,其中密氏疫霉和寄生疫霉在中国橡胶树上是首次报道。     

Hypovirulence detected in Brazilian isolates of Cryphonectria cubensis

A single 3 kb segment of double-stranded (dsRNA) was present in three of 30 Brazilian isolates of Cryphonectria cubensis . These dsRNA-containing isolates showed morphological characteristics suggestive of hypovirulence and were significantly less virulent than dsRNA-free isolates. One isolate, however, with morphological characteristics suggestive of hypovirulence, showed reduced virulence, but was free from dsRNA. Conversion of virulent isolates with normal morphology to a morphology associated with hypovirulence was achieved by pairing hypovirulent and virulent isolates of the same vegetative compatibility group (VCG). This suggests that dsRNA can be transmitted to isolates of the same vegetative compatibility group by hyphal anastomosis. Converted isolates exhibited the same hypovirulence-associated traits as those of the original dsRNA-containing hypovirulent isolates. These studies suggest that a single 3 kb segment of dsRNA alters both morphology and virulence by conferring hypovirulence on the pathogen; the first such report for Brazilian isolates of C. cubensis .     

影响黑胫病菌侵染试管烟苗的几个因素分析

 黑胫病或赤星病菌接种到试管烟苗基部进行培养,定期观察病情,结果表明:(1)高抗黑胫病而高感赤星病品种G140的幼嫩试管苗能被黑胫病菌侵染,接种病原菌30天病指100;但赤星病却与烟苗共生,病指为0。(2)接种黑胫病菌后,高感品种小黄金1025较G140凋萎死亡迅速,二者差7~10天;同一品种内单倍体较二倍体凋萎死亡迅速。(3)试管烟苗继代后7天内,极易遭黑胫病菌侵染,抗感品种间无差异;继代后10天,抗感品种间差异显著;继代后时间继续延长,烟苗抗病性有增加趋势。(4)28℃左右黑胫病菌侵染能力强而稳定,15℃能够侵染,8℃以下失去侵染能力。     

烟草黑胫病菌致病性分化和烟草品种的抗病性差异

用游动孢子浸根接种法对我国主产烟区的117个烟草黑胫病菌(Phyto-phythora parasitica var.nicotianae)致病性测定结果表明，黑胫病菌茵株问致病性存在明显差异，病情指数范围4．66—84．30，强、中和弱致病性菌株各占11．1l％、58．97％和29．91％。对国内主要的59个烟草品种经室内和大田的抗病性鉴定表明，目前尚没有抗黑胫病菌的免疫品种，但不同烟草品种抗性差异明显，其中Coker371G、NC82、K346和单育三号等品种有较强的抗病性，且室内鉴定与大田鉴定结果基本一致。