New virulent race of Phialophora gregata f. sp. adzukicola associated with continuous cultivation of adzuki bean cultivar Acc259

Adzuki bean cultivar Acc259, which is resistant to races 1 and 2 of Phialophora gregata f. sp. adzukicola, was used as a breeding resource for resistance to brown stem rot (BSR). During the third year after two successive cultivations of Acc259, a severe outbreak of BSR occurred in an experimental plot at the Tokachi Agricultural Experiment Station, Hokkaido, Japan. The isolates obtained from diseased plants were virulent to Erimo-shozu (susceptible to all races) and Acc259 but avirulent to Kita-no-otome (resistant to race 1 but susceptible to race 2). The existence of a new race of P. gregata f. sp. adzukicola, designated race 3, was determined; and its frequency in the plot soil was shown to increase from 16.7% before planting Acc259 to 100% after the third year. Of 140 isolates from the commercial production area that were formerly identified as race 1, 13 were actually race 3 and were restricted to certain limited fields.     

Characterization of biotin-autotrophic isolates derived from naturally occurring auxotrophic race 2 isolates of <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f. sp. <Emphasis Type="Italic">lactucae</Emphasis>

Race 2 isolates of Fusarium oxysporum f. sp. lactucae have been recognized as biotin auxotrophs and consequently have restricted growth on Puhalla's minimal medium (MM), which contains no biotin. Biotin-autotrophic isolates were raised from race 2 isolates through cultural mutation that grew as well on MM as they did on MM supplemented with biotin. These autotrophs were identical to the parental isolates in pathogenicity on race differential cultivars of lettuce (Patriot, Banchu Red Fire, and Costa Rica No. 4), and thus were designated as race 2. A vegetative compatibility test indicated that the autotrophic isolates fell into the same vegetative compatibility group as the parents. Culture filtrates of the autotrophs allowed abundant growth of the parental auxotroph on MM, and, through a competitive enzyme-binding assay, biotin was detected in the culture filtrates. These results suggest that biotin auxotrophy in the natural race 2 isolates has no direct relation to pathogenicity, qualitatively defined as physiological race, or to vegetative compatibility.     

甜瓜枯萎病不同生理小种的鉴定方法

甜瓜枯萎病是影响甜瓜生产的主要病害之一,由尖镰刀菌甜瓜专化型(Fusarium oxysporum f.sp.melonis,简称FOM)的病原菌侵染所致。目前,研究发现有4种生理小种(0、1、2、1.2)、3个抗病主基因(Fom1、Fom2、Fom3)。本文介绍了一种在美国用来鉴定枯萎病不同生理小种的标准方法,供生产和育种鉴定用。     

影响生丝强伸度因子的探讨

本试验以不同的蚕品种、饲养季节、给桑回数、蔟中环境条件生产的原料茧,以及煮茧生熟程度,不同定粒配茧,不同缫丝车速等缫丝工艺,探讨了上述诸因子与生丝强伸度的关系.分析了影响生丝强力的因素,提出了改善生丝强伸度的意见.     

美国水稻品种对稻瘟病小种IE-1k、IB-33、IB-49和IC-17的抗性遗传

1994年10月至1995年5月，在美国阿肯色大学水稻研究推广中心的温室，对5个美国水稻品种Katy、Lemont、L202、RA73和Bond、其F1、F2和部分组合的F3随机选系，用4个主要美国稻瘟病菌小种IE-1k、IB-33、IB-49和IC-17进行接种鉴定，通过完全双列杂交进行遗传分析的研究。结果表明：所有的亲本对IB-33感病；除RA73外，其他亲本对IE     

我国大豆主产区大豆胞囊线虫群体分布及致病性分化研究

为了明确我国大豆主产区大豆胞囊线虫群体的发生分布及致病性分化情况,同时也为我国大豆胞囊线虫防治及抗病育种工作提供依据,本研究在全国范围内开展大豆胞囊线虫种群监测工作,对2012-2014年国家大豆产业体系的29个大豆试验站所辖150个示范县进行大豆胞囊线虫的种群密度检测,并在国际统一的鉴别寄主上进行生理小种鉴定。明确了大豆胞囊线虫在我国20个省(市/自治区)发生分布,总检出率达69.4%。并对其中11个群体进行生理小种鉴定,共鉴定出生理小种5个,即1、2、3、4和14号生理小种。其中安徽宿州、甘肃镇原、内蒙古赤峰、陕西延安和宁夏银川的鉴定此前未见报道。2012-2014年我国大豆胞囊线虫病害的发生比较严重,平均胞囊量高达99个·L~(-1),我国大豆胞囊线虫致病性分化并无明显变化,鉴定结果中1、3和4号生理小种出现频率较高,为72.7%。     

中国大豆种质资源抗大豆孢囊线虫5号生理小种鉴定研究

１９９２－１９９５年,应用田间自然病圃和病土盆栽鉴定方法,对黑龙江,河北,山东,安徽,福建和广东等２１个省市保存的３３９１份栽培大豆和１６９份野生大豆种质资源进行了抗大豆孢囊线虫５号生理小种的抗性鉴定。     

中国大豆种质资源对大豆孢囊线虫3号生理小种抗性鉴定研究

１９９１－１９９５年，应用田间自然病圆和病土盆栽鉴定方法，对安徽、河北、福建、山东等２４个省市保存的３３５５份栽培大豆种质资源和１８６份野生大豆种质资源分别进行大豆孢囊线虫３号生理小种的抗性鉴定。     

近年丹东地区稻瘟病发生动态分析

1999~2005年,7年间在丹东地区的生产田和试验田中,采集了180余份2000余个稻瘟病标样;采用单孢分离法分离应用有效单孢菌株92个;经中国7个鉴别品种上鉴定,92个单孢菌株划分为7群26个生理小种;丹东地区稻瘟病菌优势种群为ZF、ZA和ZE群;采用室内苗期和田间成株期结合的鉴定方式,7年间鉴定丹东地区水稻品种(系)56个;其中表现较为抗病的品种有:东研2号、港辐5号、辽东6号、中丹4号、丹9823、东选2号、丹粳10号、丹137等。     

2012年云南省会泽县马铃薯晚疫病菌小种结构分析

利用11个含有不同单显性(R1、R2、R3、R4、R5、R6、R7、R8、R9、R10、R11)抗马铃薯晚疫病的鉴别寄主,对云南省会泽县村同一发病田块前、中、后期3个群体的马铃薯晚疫病菌59、158和75个菌株进行毒性频率和小种鉴定,分别鉴定出31、60和30个小种,大部分小种只检测到一次,其中优势小种为超级小种(含有11个毒性基因的晚疫病菌),占整个群体的53.33％;随着发病时间的推移,优势小种频率、小种复杂度呈上升趋势,但小种多样性呈降低趋势,在马铃薯生育期间除了avr4外,其它毒性基因的频率未发生显著变化.实验结果表明云南省马铃薯晚疫病菌小种演化速度快,小种结构复杂,在该地区种植起源于Solanum demission的R1～R11抗性基因存在较高的失效风险.