Phytophthora infestans field isolates from Gansu province, China are genetically highly diverse and show a high frequency of self fertility.

The genetic diversity of 85 isolates of Phytophthora infestans collected in 2007 from Gansu province in China was determined and compared with 21 isolates collected before 2004. Among them, 70 belonged to the A1 mating type and 15 were self-fertile (SF). The mitochondrial DNA haplotypes revealed both Ia (25%) and IIa (75%) haplotypes. Metalaxyl resistance occurred with high frequency (54%) in Gansu. Simple sequence repeat (SSR) genotyping revealed 26 genotypes (13 from the Tianshui region) among the 85 isolates, and 18 genotypes among the 21 isolates collected before 2004, without overlap in genotypes detected in the two groups. Cluster analysis showed clear subdivisions within the different mating type isolates. Among Gansu's isolates, Nei's and Shannon's diversity indices were highest in isolates collected in Tianshui where both A1 and SF isolates were found. Analysis of molecular variance of isolates from Gansu indicated that 51% and 49% of the variance was explained by within-area and among-area variance, respectively. The results suggest that the occurrence of SF isolates increases the risk of sexual reproduction, the formation of oospore as initial inocula in the field, and affects the genotypic diversity in the population.

Han M ，Liu G ，Li JP ，Govers F ，Zhu XQ ，Shen CY ，Guo LY ... -  《-》

Population Structure of the Late Blight Pathogen Phytophthora infestans in a Potato Germplasm Nursery in Two Consecutive Years.

Tian Y ，Yin J ，Sun J ，Ma H ，Ma Y ，Quan J ，Shan W ... -  《PHYTOPATHOLOGY》

Phytophthora infestans isolates from Northern China show high virulence diversity but low genotypic diversity.

Guo J ，van der Lee T ，Qu DY ，Yao YQ ，Gong XF ，Liang DL ，Xie KY ，Wang XW ，Govers F ... -  《PLANT BIOLOGY》

Characterization of Phytophthora infestans populations in northwestern Algeria during 2008-2014.

A total of 161 Phytophthora infestans isolates, collected from infected potato and tomato plants during 2008-2014, were characterized based on mating type, metalaxyl sensitivity and polymorphism at 12 simple sequence repeat (SSR) loci, in order to investigate the population of P. infestans in the north-west of Algeria, an emerging potato production region. The majority of isolates were of A2 mating type (112 isolates). A high percentage (89 %) of resistance to metalaxyl among isolates was detected. The metalaxyl resistant phenotype was present in both mating types with a higher percentage in A2 mating type isolates. SSR-based genotypic analysis of P. infestans population showed a low diversity. Genotype 13_A2 was the predominant in the population with a frequency of 67 % followed by 2_A1 (21 %) and 23_A1 (5 %). Genotype 23_A1 was detected only in tomato and potato isolates collected in 2013 and 2014.

Rekad FZ ，Cooke DEL ，Puglisi I ，Randall E ，Guenaoui Y ，Bouznad Z ，Evoli M ，Pane A ，Schena L ，Magnano di San Lio G ，Cacciola SO ... -  《Fungal Biology》

Genetic analysis of Phytophthora infestans populations in the Nordic European countries reveals high genetic variability.

Late blight, caused by the oomycete Phytophthora infestans, is the most important disease of potato (Solanum tuberosum). The pathogen is highly adaptable and to get an overview of the genetic variation in the Nordic countries, Denmark, Finland, Norway and Sweden we have analyzed 200 isolates from different fields using nine simple-sequence repeat (SSR) markers. Forty-nine alleles were detected among the nine SSR loci and isolates from all four Nordic countries shared the most common alleles across the loci. In total 169 multilocus genotypes (based on seven loci) were identified among 191 isolates. The genotypic diversities, quantified by a normalized Shannon's diversity index (H(s)), were 0.95 for the four Nordic countries. The low F(ST) value of 0.04 indicates that the majority of variation is found within the four Nordic countries. The large number of genotypes and the frequency distribution of mating types (60% A1) support the hypothesis that sexual reproduction is contributing notably to the genetic variation of P. infestans in the Nordic countries.

Brurberg MB ，Elameen A ，Le VH ，Naerstad R ，Hermansen A ，Lehtinen A ，Hannukkala A ，Nielsen B ，Hansen J ，Andersson B ，Yuen J ... -  《Fungal Biology》