江苏省稻瘟病菌有性态的研究

用标准菌株对1997－1999年在江苏吴江市、宜兴市、通州市、高邮市和赣榆县采集的325个稻瘟病菌单孢分离菌株的可育性和交配型进行了测定,结果表明江苏省稻瘟病菌菌株的育性较低,可交配率为22．77％,可育率仅为7．08％。不同年份、不同地区采集的稻瘟病菌菌株的性亲和力和交配型有较大的差异,三年的交配率分别为26．61％、8．26％和33．64％;通州地区和赣榆地区菌株的交本相对较高,分别为26．15％和25．42％,宜兴地区菌株的交配率较低,只有15．38％。江苏省稻瘟病菌菌株的交配型在不同年份亦出现很大差别,1997年29个可交配菌株中有21个菌株表现为MAT1－2交配型,而1999年36个可交配菌株均为MAT1－1交配型。用江苏省稻瘟病菌的可育菌株进行互交,25个组合中只有6个组合能产生子囊壳和子囊,但均不产生子囊孢子,提示江苏省稻瘟病菌在田间产生健康有性后代的几率不大。对杂交后代的遗传学分析表明,菌株的交配型是受单基因控制的。     

云南两个县陆稻稻瘟病菌稻巨座壳交配型测定及致病性分析

2014年,自云南省沧源县及耿马县陆稻地方品种上分离99个稻瘟病菌稻巨座壳单孢菌株,采用4个已知交配型的标准菌株对其进行育性和交配型测定。结果表明,两地稻巨座壳菌株具较高的育性,平均可交配率高达90.8%,且可育菌株中,MAT1-1和MAT1-2菌株分别占60.9%和39.1%;分别随机对沧源县南撒村和班考村同一田块MAT1-1型和MAT1-2型可育两性菌株进行交配,均能发育形成成熟的子囊孢子,说明该陆稻地区稻巨座壳菌的可育菌株数量丰富,且于适宜条件极有可能产生有性世代;利用22个以丽江新团黑谷为背景、持有不同抗稻瘟病基因的单基因系对分离的99个稻巨座壳菌株的致病性进行测定,明确了不同菌株的致病性,且发现Pik-h、Piz-t、Pi5及Pi9基因表现出良好的抗性,平均抗病频率达到90.0%以上、是抗病育种的优异抗原;同时,菌株对特定抗性基因致病性的明确,也为选用不同菌株的组合开展有性杂交,构建遗传群体开展稻巨座壳菌无毒基因的克隆鉴定奠定了基础。     

氯唑灵诱导恶疫霉发生异宗配合变异与变异株交配型遗传

以化学农药氯唑灵诱变天然同宗配合恶疫霉Ｐｈｙｔｏｐｈｔｈｏｒａｃａｃｔｏｒｕｍ（Ｌｅｂｅｒ＆Ｃｏｈｎ）Ｓｃｈｒｏｔ的５个野生型菌株,从其中４个菌株获得了异宗配合变异株．氯唑灵的有效诱变浓度为１０～４０μｇ／ｍｌ,以２０μｇ／ｍｌ处理４～８周效果最好。所获得的异宗配合变异株在１２℃、黑暗条件下保存,２个月内有４０％左右的菌株保持异宗配合特性,７个月后仍有少数变异株保持异宗配合特性。异宗配合变异株的交配型在单游动孢子后代中发生分离,出现了Ａ1、Ａ２、Ａ１,Ａ2、Ａ１Ａ２、Ａ０５种交配型的菌株。上述各交配型在单游动孢子后代中均持续分离,在其单孢后代中检测到３～５种交配型的个体。上述结果提示疫霉属卵菌性别的产生是由同宗配合演化为异宗配合并可能同时分化产生不同的交配型,从遗传学角度阐明了自然条件下和实验室条件下疫霉菌交配型互变现象的可能机理。     

江苏省稻瘟病菌的毒性多样性及水稻品种的抗病性

在13个已知日本抗病基因品种上检测1997－1999年采集自江苏省吴江,赣榆,通州,高邮和宜兴等5个代表地区的324个稻瘟病菌株的毒性,结果可将上述菌株划分为90种毒性类型,表明江苏省稻瘟病菌存在着丰富的毒性多样性,毒性类型组成在地区间存在较大的差异,并且随着时间的推移,稻瘟病菌毒性类型组成有差异加大的趋势,在已知抗病基因品种上测定江苏省稻瘟病菌的毒力,结果显示：Pi-k^3,Pi-ta,Pi-ta^2和Pi-sh等抗病基因对江苏省的稻瘟病菌的抗谱很窄,而Pi-i,Pi-z,Pi-z^t和Pi-b等抗病基因的抗谱比较宽,可作为抗源加以利用,用6个代表性毒性类型菌株接种江苏省80筱水稻主载品种和新育成品种,品种抗性分析表明,上述水稻品种中的籼稻和杂交稻对江苏省稻瘟病菌具有较高的抗性,而粳稻品种的抗性较差,上述研究结果为利用水稻品种抗性多样性控制稻瘟病提供了依据。     

中国番茄晚疫病菌交配型及其分布研究

本文对中国番茄晚疫病菌交配型的发生和分布及病菌的生物学特性进行了研究,结果表明,我国主要番茄产区晚疫病菌以A1交配型为主,占总菌株数的96.02%;1999~2001年间从全国18个省市采集的201个番茄晚疫病菌株中,仅发现8个A2交配型菌株,分布于广西、云南、河北和福建;被测菌株在10%V8培养基上菌落生长均受到一定的限制,而在黑麦培养基上菌落的生长速度、产孢量有明显的差异,但菌落形态与交配型类型不相关。     

中国蜜环菌生物种与北美种的交配关系

将中国三个未知蜜环菌生物种A、C、D的38个代表菌株与北美蜜环菌A．sinopina、A．calvescens、A．nabsnona、A．gemina、A．ostoyae、NABSX等六个种的22个代表菌株进行了配对试验,结果表明中国生物种A与北美种A．sinopina互交可育,属于同一种。中国生物种C与任一北美种都互交不育,不存在部分可育现象,为亚洲特有种。中国生物种D与欧美的A．ostoyae的两个菌株互交可育,实验证实该种另外四个欧美菌株已经失去交配能力,因此确认中国生物种D与A．ostoyae属于同种。     

两株生防荧光假单胞杆菌的室内筛选试验

从番茄根际土壤中筛选出11株对水稻稻瘟病菌具拮抗活性的细菌原始菌株,其发酵滤液对稻瘟菌菌丝生长抑制率达50％以上的菌株有8个。依据拮抗活性测定结果,确定AbⅢ745和AbⅢ763的单胞分离后代AbⅢ745-6和AbⅢ763-1为最优菌株,其对稻瘟病菌的抑制率分别达96.88％和78.57％,对小麦全蚀病菌、小麦根腐病菌及番茄早疫病菌也有一定的抑制作用。经初步鉴定,AhⅢ745-6和AbⅢ763-1属于假单胞菌科荧光假单胞杆菌。     

掘氏疫霉遗传学研究II．交配型遗传与变异的研究

本研究以掘氏疫霉P“yl口外埔o,o dr~cksleri丁ucke r野生型菌株的单游动孢子无性系为亲本,测定了自交、杂交后代交配型的遗传,经Kmno·处理引起的交配型变异以及Ft代可自孕单卵孢株有性生殖后代交配型的遗传与变异。聚碳膜间隔配对诱导A,和^,菌株自交产生的卵孢子经H zot处理索0激萌发(萌发率1 z～16％)获得单卵孢株。交配型测定结果表明,^t和A,亲本自交st代单卵孢株均保持与亲本一致的交配型。用KMnO．处理上述卵孢子导致A-和^z亲本的部分s一代单卵孢株出现自孕现象,少数A,亲本自交后代改变为A：交配型;从A。交配型亲本的s-代可自孕菌株产生的卵孢子萌发所建立的单卵孢株中,同时获得扎和^。交配型菌株。上述结果不支持San somc关于疫霉菌AhA,交配型分别由纯合、杂合基因控制的假说,进一步证明了Ko关于交配型抑制因子控制交配型表达的假说的合理性。 掘氏疫霉种内菌株直接配对产生的卵孢子用HtO,刺激萌发获得Ft代单卵孢拣。测定结果表明,在F。代出现A。A,、A,A;、A口4种交配型的单卵孢株,其比例因不同亲本组合而有较大差异oF。代出现的^。A,菌株自孕产生的卵孢子经HtO,处理刺激萌发建立自交系,观察到^。^：交配型在有性生殖后代发生分离,各交配型比例因亲本不同而异o A·At菌株的自孕能力在单游动孢子无性系后代可稳定遗传,认为F-代出现的AJAt个体来自亲本的杂交。AtA-单卵孢株保藏4～6个月后大多仍具自孕能力,少数改变为Az交配型。     

一种新的人兽共患传染病——狐阴道加德纳氏菌病的研究：V.狐阴道…

将我国６个省（区）、１３个主要狐场分离的１４５株狐阴道加德纳氏菌,进行抗原性、免疫原性测定,从每场分离菌中选出１￣３个优良株进行血清型研究。凝集素交叉吸收试验证实,选出的２６株菌可划分为３个血清型,以此３个血清型代表株制备因子血清,余下１１９株菌中,１０８株在所划分的３个血清型内,１１株未能定型。在３个血清型中,Ｉ型菌株数占定型菌数的７９．１％,因而确定,Ｉ型菌是国内狐场狐阴道加德纳氏菌主要流行型     

香菇自然群体中个体间的空间分布及其遗传联系*

应用体细胞不亲和性反应、交配型因子分析和基因组ＤＮＡ的ＲＡＰＤ分析,研究了一个分布于方圆约１ｋｍ的６根倒木上的１８个香菇野生菌株间的遗传差异。结果表明,该群体大多数菌株间配对（８０．４％）体细胞不亲和,而同一倒木菌株间配对的体细胞亲和率达 ６２．５％。不同倒木菌株间未发现体细胞亲和的配对。该群体存在 １１个特异的Ａ因子和７个特异的Ｂ因子。同一倒木的菌株有的交配型因子相同,有的则不同。不同倒木的菌株大多数交配型因子不同,未发现交配型因子完全相同的菌株。ＲＡＰＤ分析显示,体细胞亲和的菌株,交配型因子完全相同的菌株,在基于ＤＮＡ相似系数的遗传相关聚类中,首先聚为小类。总起来看,在自然群体中,香菇个体间的遗传差异与其空间分布之间存在一定的联系,随着空间距离的增大,菌株间的异质性相应增高。     

Determining the Fertility Status of Setaria Infecting <Emphasis Type="Italic">Magnaporthe grisea</Emphasis> Isolates with Standard Testers and Identification of Tolerant Cultivar of <Emphasis Type="Italic">Setaria italica</Emphasis>

A total of 128 isolates of Setaria-infecting Magnaporthe grisea strains were obtained from different states of South India which includes sampling sites from Tamil Nadu, two from Karnataka, one from Andhra Pradesh and Kerala. Out of the selected 128 isolates 30 strains were tested with MAT1-1 and MAT1-2 fertile standard testers to determine their mating type. None of the 30 Setaria isolates produced perithecia with fertile testers. However, when monoconidial isolates were mated among themselves, isolates from the same field produced only barren perithecia and the tester isolates were able to mate readily with finger millet isolates. This is the first report of the mating-type studies on Setaria infecting Magnaporthe grisea with standard testers. This result indicates that the Setaria infecting population is infertile. In pathogenicity assay, it was found that 9 out of the 22 Setaria accessions were highly susceptible to Setaria strains of the blast fungus and seven cultivars/accessions were resistant to blast pathogen. Various virulence reactions were scored according to Standard Evaluation System.     

Mating-type Distribution and Fertility Status in Magnaporthe grisea Populations from Argentina

Isolates of Magnaporthe grisea causing gray leaf spot on rice were collected in Argentina and analyzed for mating distribution and fertility. One hundred and twenty-five isolates of M. grisea were collected from rice plants between 2000 and 2003. Each isolate was tested for mating type through a polymerase chain reaction based assay. All M. grisea isolates from Argentina belonged to a single mating type, MAT1.1. The fertility status of isolates was determined using controlled crosses in vitro, pairing each isolate with GUY11 and KA9 (MAT1.2 standard hermaphroditic testers). Production of perithecia was scarce among isolates of the blast pathogen since a low percentage of them (7.2%) developed perithecia with only one of the fertile tester (KA9); all crosses failed with the other tester strain. Asci and ascospores were not observed. The presence of only one mating type and the absence of female fertile isolates indicate that sexual reproduction is rare or absent in M. grisea populations associated with rice in Argentina.     

Fertility status and distribution of mating type alleles of the rice blast fungus, Magnaporthe grisea in northern Iran

This study was carried out using 155 monoconidial isolates collected from different areas of two major rice growing provinces in northern Iran, including 94 isolates from Guilan and 59 isolates from Mazandaran. Among 94 isolates from Guilan, 92 and two isolates recovered from rice and crabgrass (Digitaria sp.), respectively. All 61 rested isolates from Mazandaran were recovered from rice. All isolates were evaluated for in vitro sexual fertility and mating type status by pairing with Mat 1-1 and Mat 1-2 fertile standard hermaphrodite isolates including Br48 and Th12 (Mat 1-1) and KA9 and TH16 (Mat 1-2). Of 155 isolates, 98 (63.2%) were fertile and 57 (36.8%) were infertile and produced no perithecium when mated with standard isolates. Among 98 fertile isolates, 96 isolates were identified as Mat 1-1 and two isolates as Mat 1-2. All Mat 1-1 isolates were obtained from rice and two Mat 1-2 isolates obtained from crab grass. No Mat 1-2 isolate was identified from rice in this study. Both mating types were found in Guilan but all isolates recovered from Mazandaran were identified as Mat 1-1. Male fertility predominated in fertile Mat 1-1 and Mat 1-2 isolates from all sampling sites in northern Iran, and no female fertility was detected. This is the first report of existence of Mat 1-2 allele in Magnaporthe grisea population in Iran.     

Study on genetic diversity of Magnaporthe grisea using PCR and determination of the mating type alleles distribution in Mazandaran province, Iran

The population structure of Magnaporthe grisea, the causal agent of the rice blast, was analyzed in Mazandaran province, using DNA fingerprinting based on RAPD-PCR by means of three primers including "I", "D" and "H". Total DNA of 47 isolates was extracted and amplified according to a specific PCR program. As a result, variable length fragments were generated. Each isolate was subjected to DNA fingerprinting and clonal lineages were determined. Phenetic analysis differentiated three distinct fingerprint lineages. In order to study on fertility status and distribution of the mating type idiomorphs (alleles), 72 monoconidial isolates from Mazandaran province were paired with four standard fertile hermaphrodite isolates. The mating type of 36 isolates was determined as Mat 1-1. The others (36 isolates) did not form any perithecia in pairing with standard isolates     

Isolation of the Mating-Type Genes of the Phytopathogenic Fungus Magnaporthe Grisea Using Genomic Subtraction

Using genomic subtraction, we isolated the mating-type genes (Mat1-1 and Mat1-2) of the rice blast fungus, Magnaporthe grisea. Transformation of M. grisea strains of one mating type with a linearized cosmid clone carrying the opposite mating-type gene resulted in many ``dual maters,' strains that contain both mating-type genes and successfully mate with both Mat1-1 and Mat1-2 testers. Dual maters differed in the frequency of production of perithecia in pure culture. Ascospores isolated from these homothallic crosses were either Mat1-1 or Mat1-2, but there were no dual maters. Most conidia from dual maters also had one or the other of the mating-type genes, but not both. Thus, dual maters appear to lose one of the mating-type genes during vegetative growth. The incidence of self-mating in dual maters appears to depend on the co-occurrence of strains with each mating type in vegetative cultures. In rare transformants, the incoming sequences had replaced the resident mating-type gene. Nearly isogenic pairs produced from three M. grisea laboratory strains were mated to investigate their fertility. One transformant with switched mating type appears to have a mutation that impairs the development of asci when its mating partner has a similar genetic background. The M. grisea Mat1-1 and Mat1-2 genes are idiomorphs approximately 2.5 and 3.5 kb in length, respectively.     

Sexual reproduction in the soybean sudden death syndrome pathogen Fusarium tucumaniae

We investigated the sexual reproductive mode of the two most important etiological agents of soybean sudden death syndrome, Fusarium tucumaniae and Fusarium virguliforme. F. tucumaniae sexual crosses often were highly fertile, making it possible to assign mating type and assess female fertility in 24 South American isolates. These crosses produced red perithecia and oblong-elliptical ascospores, as is typical for sexual members of the F. solani species complex. Genotyping of progeny from three F. tucumaniae crosses confirmed that sexual recombination had occurred. In contrast, pairings among 17 U.S. F. virguliforme isolates never produced perithecia. Inter-species crosses between F. tucumaniae and F. virguliforme, in which infertile perithecia were induced only in one of the two F. tucumaniae mating types, suggest that all U.S. F. virguliforme isolates are of a single mating type. We conclude that the F. tucumaniae life cycle in S. America includes a sexual reproductive mode, and thus this species has greater potential for rapid evolution than the F. virguliforme population in the U.S., which may be exclusively asexual.     

Identification of Races and Mating Types of Cochliobolus carbonum from Corn in the Yunnan Province in China

Northern corn leaf spot, a foliar disease caused by Cochliobolus carbonum, has become prevalent in southwestern China, especially in the Yunnan Province. Races and mating types were identified for 169 isolates collected from 13 prefectures of Yunnan by artificial inoculation using six hybrid corns as differential hosts and by crossing with three standard mating strains: CC092 (MAT1‐2), CC120 (MAT1‐1) and CC026 (MAT1‐1). Results showed the existence of three races: CCR1 (one isolate), CCR2 (43 isolates) and CCR3 (125 isolates). Most isolates were moderately or weakly virulent with only five being highly virulent. CCR3 was widely distributed and significantly more virulent than CCR2 that coexisted with CCR3 in many locations. On Sach's nutrient agar, 20.71% of the Yunnan isolates self‐mated, forming sterile perithecia. Fully developed perithecia could be formed between isolates of different geographic origins, but only 15.98% strains mated successfully with CC092 and 5.33% formed mature perithecia with 4–6 ascospores per asus. Similar results were obtained in crossing with CC026 or CC120. Mating could also occur between CCR3 and CCR2. Both mating types were found in Yunnan with 84 MAT1‐1 strains (one CCR1, 10 CCR2 and 73 CCR3) and 85 MAT1‐2 strains (33 CCR2 and 52 CCR3) and they coexisted in most areas. To identify the mating type rapidly, three specific primers were successfully developed and employed to amplify the mating‐type genes, with stable patterns of 1627 and 876 bp fragments obtained from MAT1‐1 and MAT1‐2 isolates, respectively. The ratio between MAT1‐1 and MAT1‐2 was 1 : 1, indicating that the mating‐type genes segregated randomly in the field naturally.     

Pathogénie Comparée et Signe Sexuel des Isolats Marocains de Pyricularia grisea (Magnaporthe grisea) Originaires de Riz et de Stenotaphrum secundatum

Moroccan isolates of Pyricularia grisea (Magnaporthe grisea) from Oryza sativa and Stenotaphrum secundatum were crossed with standard fertile isolates (mating type Mat 1.1 and Mat 1.2) by using the three‐points culture method on oatmeal agar. Only Mat 1.1 isolates from rice were identified and considered to have only the ability to function as males, whereas no isolate from S. secundatum mated with Mat 1.1 or Mat 1.2. Cross‐inoculation studies using Pyricularia grisea (M. grisea) isolates from Oryza sativa and S. secundatum show that rice varieties cultivated in Morocco were susceptible to isolates originating from S. secundatum. Similarly, S. secundatum was susceptible to some isolates from O. sativa.     

Population analysis of <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis> by using endogenous repetitive DNA sequences and mating-type alleles in different districts of Karnataka,India

Rice is the staple food crop of more than 60% of the population of the world. This crop suffers from blast disease caused by Magnaporthe oryzae. Information on the mating-type allele distribution and diversity of the pathogen population for the state of Karnataka, India is scanty. With this background, a total of 72 isolates of M. oryzae from rice in different districts of Karnataka were examined for identifying sexual mating alleles MAT1, MAT2 and understanding the genetic diversity based on DNA fingerprint of pot2, an inverted repeat transposon. Among 72 isolates, 44 isolates belonged to MAT1 type (male fertile) and 28 isolates were of MAT2 (female fertile) and there were no hermaphrodite isolates. In a given geographical location, only one mating type was identified. Results revealed that the isolates obtained from these regions are not sexually fertile showing predominant asexual reproduction. Hence, genetic variation observed in the pathogen may be mainly because of high copy number of transposons. A high copy number transposon, namely Pot2, was selected in our study to detect genetic diversity of the pathogen. Pot2 rep-PCR DNA fingerprinting profile showed 27 polymorphic bands with bands ranging in size from 0.65 to 4.0 kb and an average of 10 to 14 bands per isolate. Five distinct clusters were formed with two major, two minor, and one outlier. Clusters 4 and 5 are further subdivided into three sub-clusters. Some of the isolates belonging to clusters 3, 4, and 5 are interlinked as these locations are close to one another sharing common geographical parameters and boundaries. This knowledge on the sexual behavior and genetic diversity of M. oryzae is important with respect to breeding for disease resistance.