A Survey of Phytophthora Species on Hainan Island of South China

During the period 1997–2007, a comprehensive study of the occurrence and distribution of Phytophthora species was conducted on Hainan Island of South China. To date, 14 species of Phytophthora have been recovered and their distribution determined. Phytophthora nicotianae ( =P. parasitica ) is the most important species attacking a wide variety of crops, followed by Phytophthora capsici and Phytophthora citrophthora . In contrast to Phytophthora colocasiae attacking taro leaves throughout the entire island, Phytophthora cyperi was found only once on Digitaria ciliaris in Danzhou. It is of interest to note that Phytophthora heveae, Phytophthora katsurae and Phytophthora insolita are commonly found in forest soil/water of protected mountains without causing any plant diseases. Although Phytophthora species are usually terrestrial or found in fresh water, one isolate of Phytophthora resembling closely the asexual isolates of P. insolita in Hainan was obtained from decaying Rhizophora leaves submerged in seawater. An unidentified Phytophthora species producing non-papillate; internally proliferating sporangia was isolated from the soil in which Ceriops tagel and Bruguiera serangula were growing in a salt water shrimp farm.     

Characterization and pathogenicity of three Phytophthora spp. recovered from rivers in Bulgaria

Many Phytophthora species are pathogens on fruit trees and may cause destructive diseases. In the current study, we examined six Phytophthora isolates recovered from rivers in Bulgaria, representatives of the following three species: Phytophthora chlamydospora, P. pseudocryptogea and P. syringae. Morphological traits, cardinal temperatures and growth rates of the isolates were described. We found considerable variation in the size of sporangia and significant difference in the mycelial growth rates of the two P. pseudocryptogea isolates, along with multiple polymorphic sites in the ITS region of one of them. In the cases of the other two Phytophthora species, no such differences were found between the isolates. Both P. chlamydospora isolates had a lower optimum growth temperature compared with the reported in the literature for this species. In pathogenicity tests against leaves and fruits of apple, pear, cherry, apricot and plum, the isolates proved to be capable of causing infections with varying severity. P. chlamydospora showed to be the most aggressive towards the leaves, while P. pseudocryptogea isolates induced the highest percentage of decay on the fruits of all tested tree species, which may suggest partial organ or tissue specificity. The demonstrated infection capacity of the described isolates points out the investigated Phytophthora species as a potential threat for the orchards in Bulgaria, if favourable conditions are available.     

野生大豆资源对大豆疫病抗病性和耐病性鉴定

大豆疫病是大豆重要病害之一,在世界范围内导致严重经济损失。防治大豆疫病最有效方法是利用抗病或耐病品种。筛选抗性资源是发掘抗性基因和抗病育种的基础。本研究鉴定了野生大豆资源对大豆疫病的抗病性和耐病性,以期发掘优异抗源。苗期用子叶贴菌块方法鉴定104份野生大豆资源对两个不同毒力的大豆疫霉分离物PSJS2(毒力型:1a,1b,1c,1d,1k,2,3a,3b,3c,4,5,6,7,8)和PS41-1(毒力型:1a,1d,2,3b,3c,4,5,6,7,8)抗性,结果表明33份资源抗PS41-1,35份资源抗PSJS2,其中18份抗两个分离物。在抗病性鉴定基础性上,用菌层接种方法对选择的82份资源进行耐病性鉴定,发现7份高耐病性资源。这些结果表明,野生大豆中可能含有新的大豆疫病抗病和(或)耐病资源,这些抗病或耐病资源可以用于未来大豆抗病育种,以丰富大豆对大豆疫病的抗性遗传基础。     

Relative Resistance of Four Peach Rootstocks to Phytophthora cactorum and Phytophthora megasperma

Shoot samples of four peach rootstocks that are important to the peach industry in Greece: KID I, GF305, GF677, and PR204, were inoculated with Phytophthora cactorum and Phytophthora megasperma in the field and in the glasshouse and were then evaluated with regard to susceptibility. The pathogenicity of P. cactorum and P. megasperma to peach rootstocks was confirmed with an excised twig assay. The peach rootstocks showed differential susceptibility to P. cactorum . GF305 was the least susceptible and KID I was the most susceptible, which suggests that the latter rootstock is unsuitable for orchards in which the conditions are favourable for Phytophthora diseases. GF677 and PR204 were moderately susceptible. The plants that were inoculated with P. megasperma in the field and in the glasshouse showed no sign of infection whereas twigs inoculated in vitro with P. megasperma developed necrosis. GF305 was the most resistant, KID I was the most susceptible and PR204 and GF677 were moderately resistant. The present results demonstrate that none of the four peach rootstocks used in this study was completely resistant to P. cactorum , particularly when rootstocks were flooded periodically to enhance disease development. Therefore an integrated approach including host and resistance cultural practices is recommended to manage diseases caused by P. cactorum in peach orchards in Greece.     

大豆疫霉根腐病抗源筛选

由大豆疫霉菌引起的大豆疫霉根腐病是大豆生产的重要病害,该病已在我国大豆主要产区发生,并在局部地区造成较大产量损失。利用抗病品种是防治大豆疫霉根腐病最有效的方法。本研究目的是筛选大豆疫霉根腐病抗源,为病害防治和抗病品种的选育提供参考。用下胚轴创伤接种方法对120个栽培大豆品种（系）进行接种,鉴定其对10个具有不同毒力大豆疫霉菌菌株的抗性。有110个品种（系）分别抗1～10个大豆疫霉菌菌株,其中以河南大豆品种（系）对疫霉菌的抗性最丰富,安徽、湖北和山西大豆品种（系）也具有抗性多样性。120个大豆品种（系）对10个大豆疫霉菌菌株共产生57个反应型,有4个抗性反应型分别与单个抗病基因的反应型一致,有7个抗性反应型与2个已知基因组合的反应型相同,其他抗性反应型为新的类型。一些大豆品种（系）中可能存在有效的抗大豆疫霉根腐病新基因。     

大豆疫霉菌的分离与鉴定

采用叶碟诱捕法从2007年进口的美国大豆携带的土壤和2006年从黑龙江感病大豆田采集的土壤中分离出2株疫霉菌菌株,并对病原菌进行了形态特征、致病性、分子检测。结果表明:形态观察为疫霉属真菌;接种大豆后出现典型的大豆疫病症状;采用大豆疫霉的特异性引物PCR检测,2个菌株均能扩增出分子量为330 bp的特异性条带。结合形态、致病性测定和分子检测,2株病菌鉴定为大豆疫霉菌(Phytophthora sojaeKauf-mann et Gerdemann)。     

抗大豆疫霉根腐病野生大豆资源的初步筛选

由大豆疫霉菌引起的大豆疫霉根腐病是严重影响大豆生产的毁灭性病害之一.防治该病唯一经济、有效和环境安全的方法是利用抗病品种.本研究对野生大豆资源进行抗大豆疫霉根腐病初步筛选,以期探讨野生大豆的抗性水平、分布和获得抗性野生大豆资源.通过苗期接种大豆疫霉菌对412份野生大豆资源进行抗病性鉴定,有13.4%的资源抗大豆疫霉根腐病,15.3%的资源表现为中间反应类型.对野生大豆资源的来源分析表明,抗大豆疫霉根腐病野生大豆资源在我国分布广泛,其中安徽省野生大豆资源抗性最丰富.     

福建省部分地区马铃薯致病疫霉群体遗传多样性分析

致病疫霉(Phytophthora infestans)引起的晚疫病是马铃薯的一种毁灭性病害。有效控制马铃薯晚疫病需要明确致病疫霉的群体遗传结构特征。采用8对SSR引物对采自福建省福州、长乐、漳州2010年分离的95株马铃薯致病疫霉进行遗传多样性分析。结果共检测出21个等位基因和26个基因型。三个地点致病疫霉菌群体间的平均遗传分化系数FST为0.22,在8个位点中有5个位点的等位基因频率分布差异显著。三个群体的观测纯合度小于期望纯合度,观测杂合度大于期望杂合度,以无性生殖为主。结果表明福建群体的遗传多样性高,群体间的存在较高的遗传分化度。     

植物提取物对大豆疫霉菌抗菌活性的初步研究

采用Paper Disk法测定了云南省200种植物的提取物对大豆疫霉(Phytophthora sojae)的抑菌活性。结果表明,光叶合欢(Albizia lucidior)、白钩藤(Uncaria sessilifructus)及黄豆树(Albizia procera)的提取物在浓度为10μg/μL时有较好的抗菌活性,而在2.5μg/μL时只有黄豆树提取物显示出抗菌活性。并从黄豆树中分离出其抗菌的主要活性成分3-O-[α-L-arabinopyranosyl-(1→2)-β-D-fucopyranosyl-(1→6)-2-acetamidO-2-deoxy-β-D-glu-copyranosyl]echinocystic acid。     

Safflower Seedling a Selective Host to Discriminate Phytophthora melonis from Phytophthora drechsleri

Safflower seedlings were used to discriminate two morphologically similar species of Phytophthora namely P. melonis and P. drechsleri . All isolates of P. melonis from different sources could not infect safflower seedlings under high inoculum potential whereas all isolates of P. drechsleri from various hosts attacked safflower within a short period. Of 31 authentic Phytophthora species inoculated to safflower seedlings only seven species including Phytophthora asparagi , Phytophthora cactorum , Phytophthora cryptogea , Phytophthora drechsleri , Phytophthora erythroseptica , Phytophthora palmivora and Phytophthora quercina caused hypocotyls infection. All cucurbit isolates of Phytophthora from different parts of Iran and one from China could not infect safflower seedlings and were identified as P. melonis which had been confirmed previously by molecular analysis.     

Peroxidase Activity in Soybeans Following Inoculation with Phytophthora sojae

The effects of race-specific resistance as conditioned by Rps genes (rps, Rps1-k, Rps2, Rps3, Rps6) in two genetic backgrounds (Williams & Harosoy) on accumulation of soluble peroxidases were determined by a soybean peroxidase capture assay (SPCA) after inoculation with P. sojae races 2, 7, or 25. Peroxidase activity increased in all isolines during the 72 h after inoculation, but reactions varied depending on time after inoculation, genetic background, Rps gene and P. sojae race. Peroxidase activity was higher in race-specific resistant than in susceptible reactions at 72 h. after inoculation, except for plants with the Rps2 gene which confers a unique form of root resistance in addition to the whole plant race-specific resistance. Williams isolines had larger increases in peroxidase activity than Harosoy isolines when data were averaged across Rps genes, and was most evident when plants were inoculated with race 2. When soybeans were inoculated with race 7 Rps1-k resistant plants had the highest increase in peroxidase activity, but Rps2 susceptible plants had a significantly higher peroxidase activity than plants with rps, Rps3, and Rps6 that were also susceptible. Results from inoculations with race 25 were somewhat different, Rps2 resistant plants had the highest increase in peroxidase activity; however, plants with the Rps3 or Rps6 gene that were also resistant did not have a significantly higher peroxidase activity than susceptible plants with the rps or Rps1-k gene.     

黑龙江省主要栽培大豆品种(系)对大豆疫霉根腐病的多抗性评价

用下胚轴伤口接种方法接种鉴定黑龙江省60个栽培大豆品种和育成品系对5个具有不同毒力大豆疫霉菌菌株41-4、PMCl、USAR4、PSZJ6和USAR17的抗性.有50个品种(系)抗1个或1个以上茵株或表现中间类型,其中有5个、8个、16个和21个品种(系)分别对4个、3个、2个和1个菌株表现抗性或中间类型.60个品种(系)对5个菌株共产生12种反应模式,其中呈RRSSR反应类型的品种(系)可能含有Rpslα或Rpslc基因,品系农大3861可能含有Rps3c基因,呈SSSSS反应模式的品种(系)可能含有Rps7基因,或不含抗病基因;其它9种反应模式与含有已知单基因品种或单基因组合的反应模式不同,可能具有未知抗病基因.该研究结果表明,黑龙江省具有较丰富的抗大豆疫霉根腐病大豆品种(系),大部分品种(系)的抗性是有效的,可合理地用于大豆生产和抗疫霉根腐病育种.     

土壤中辣椒疫霉分离方法的研究与量化测定

从杭州、西安、广州及武汉等辣椒病田分别采集土样 ,室内晾干研碎后 ,用选择性培养基 ,采用土壤稀释平板法和组织诱饵法分离辣椒疫霉 (PhytophthoracapsiciLeonian) ,并对土壤中辣椒疫霉的密度进行量化处理。结果表明 ,利用选择性燕麦培养基 ,采用土壤稀释平板法可分离获得大量的辣椒疫霉菌株 ,而且辣椒连作田的辣椒疫霉菌密度高于轮作田。组织诱饵法试验结果表明 ,辣椒叶片诱集效果最好 ,其次是辣椒果实。     

检疫性疫霉DNA条形码标准分子构建

质粒标准分子是指含有外源基因和内源标准基因特异性片段的重组质粒分子.DNA条形码技术是通过对标准目的基因的DNA序列进行分析从而进行物种鉴定的技术.构建基于DNA条形码的质粒标准分子是DNA条形码技术应用于检测实践的要求.本研究将这两种检测鉴定技术相结合应用于检疫性疫霉的检测,构建了11种检疫性疫霉的DNA条形码标准分子,进行了测序验证,均匀性,稳定性和特异性验证.结果表明,构建的质粒标准分子准确度,均匀性,稳定性和特异性均良好,对实际口岸检验检疫工作具有实践应用价值.     

The Phytophthora diseases of stone fruit trees in Greece

Phytophthora collar and crown rots are serious soilborne diseases which for a long time have caused considerable losses in stone fruit orchards in Greece. A number of Phytophthora species are notorious for being the cause of crown and root rots in Greek stone trees, including P. cactorum, P. citricola, P. cryptogea, P. drechsleri, P. nicotianae, P. citrophthora, P. syringae and P. megasperma. The most important Phytophthora species is P. cactorum, while P. syringae and P. citrophthora may be locally significant. The economic consequences from death of peach trees and yield losses caused by this disease in Imathia County are serious.     

辽宁省辣椒疫病菌多态性及致病力分化研究初探

【目的】明确辽宁省辣椒疫病菌多态性及致病力分化与区域性关系。【方法】利用SRAP技术对辽宁省25个辣椒疫病菌菌株进行了PCR扩增及NTSYS-PC聚类分析,用灌根法进行致病力分化试验并对试验结果进行SPSS 11.5分层聚类分析。【结果】利用筛选出的27组引物对25个菌株进行扩增,得到578条条带,每对引物多态性比率在84%?100%之间,多态性丰富;供试菌株间遗传相似性较高,相似系数0.56?0.91,以相似系数0.68为阈值划分,25个菌株可聚为4组。试验菌株80%为中等致病力,聚类结果较为分散。【结论】供试菌株没有表现出明显的区域性特征,菌株致病力强弱分化区域特征性规律不明显。     

Virulence of Phytophthora sojae in the Pampeana Subregion of Argentina from 1998 to 2004

Phytophthora root rot is one of the most serious diseases of soybeans in Argentina. Surveys of commercial fields and trial plots of soybean were conducted throughout the northern Pampeana subregion (Argentina) between 1998 and 2004. A total of 193 isolates of Phytophthora sojae were collected and classified into races or virulence formulae. Among the 173 isolates tested on 8 differentials, 42 different pathotypes were detected, including 18 described races. Races 1, 4, 5, 7, 9, 13, 23 and 24 were found in both plants and soils, whereas races 2, 3, 6, 8, 11, 14, 15, 17, 43 and 44 were only isolated from plants. An additional 19 pathotypes were described from 20 isolates tested in Canada on the expanded set of 14 differential cultivars. Currently, all Rps genes/alleles associated with resistance have been defeated, indicating an increased complexity of virulence within the P. sojae populations in the region. The great increase in virulence complexity found in this study is most likely a result of a long period of continuous production of soybean cultivars with Rps genes and the extensive adoption of the no‐tillage system.     

Phytophthora Crown and Root Rot of Apricot Caused by Phytophthora palmivora in Turkey

Forty‐nine Phytophthora isolates were obtained from roots and crown of apricot trees with symptoms of decline grown in commercial orchards in Malatya, Elaz?? and Diyarbak?r provinces, Turkey, in 2011 and 2013. All of the recovered isolates were identified as Phytophthora palmivora on the basis of morphological characteristics. Blast analysis of ITS region sequences of rDNA of 5 isolates revealed 100% identity with a reference isolates of P. palmivora from GenBank. Isolates of P. palmivora were pathogenic on 12‐month‐old wild apricot rootstock ‘Zerdali’ plants that were wound inoculated on the roots and on the crown. This study demonstrated that P. palmivora is the cause of the crown and root rot found on apricot in Turkey. To our knowledge, this is the first report of P. palmivora on this host plant.     

马铃薯POTHR-1 cDNA的克隆及晚疫病菌和其他非生物因子诱导表达分析

利RACE和重叠延伸相结合的方法,从经晚疫病菌接种诱导的马铃薯水平抗性材料叶片中克隆了一个POTHE 1基因(potato Phytophthora infestans induced hypersensitive response related protein gene)的全长cDNA.序列分析表明,该基因编码225个氨基酸,与烟草harpin诱导蛋白基因hinl有很高的同源性(编码区核苷酸和氨基酸序列分别为83%和81%).Southern杂交结果显示在马铃薯基因组中有2～3个拷贝.对其诱导表达模式研究表明:晚疫病病原菌接种36 h后,该基因表达迅速增加;机械伤害及茉莉酸(JA)处理能够诱导表达;渗透胁迫(NaCl浸泡)能够诱导其微弱表达;但水杨酸(SA)不能诱导表达.该基因可能和病原与寄主互作时寄主产生过敏反应及细胞生理性死亡有关.