Abstract A total of 288 (202 from potato and 86 from tomato) isolates of Phytophthora infestans were collected from 1998 to 2007 in China. The isolates were characterized based on mating type, in vitro metalaxyl sensitivity, virulence on potato differentials, allozymes of glucose‐6‐phosphate isomerase ( Gpi ), peptidase ( Pep ), and mitochondrial DNA (mtDNA) haplotype and examined by DNA‐based simple sequence repeat (SSR) and random amplified polymorphic DNA (RAPD) fingerprinting. The majority (283 of 288) of the isolates were of the A1 mating type, the other three were the A2 mating type and two were the A1A2 mating type. Resistance to metalaxyl was frequently observed, with 248 (86.1%) resistant, 21 (7.3%) intermediate and 19 (6.6%) sensitive isolates identified. Virulence was assessed for 125 isolates on a set of 11 potato differentials and 61 races were detected. Most isolates were virulent on the differential genotype with gene R3, and all known virulence genes were found, with race 3.4.7.11 being the most common. This pattern did not appear to be associated with geographic origin, sample type, mating type or metalaxyl sensitivity. The dominant banding patterns for Gpi were 100/100/111 (176 isolates) and 100/100 (109 isolates), but genotypes 86/100 and 100/111 were also identified. All isolates tested were homozygous (100/100) at the Pep locus. The majority (205 of 288) of isolates tested was of mtDNA haplotype IIb, 76 were haplotype IIa and seven were the rare Ib haplotype. The genetic diversity of 60 representative isolates from China was assayed by two types of molecular markers, RAPD and SSR. A high level of polymorphism was found. The results demonstrated the diverse phenotypic and genotypic structure of the current populations of P. infestans in China.
Global emergency mobile communication system proposed in this paper can accomplish realtime call and text message communication based on TDRSS. It can be applied to ocean sailing, disaster relief, landing ground searching. System constructure and operational mode are designed. The design scheme of the mobile terminal is also proposed in this paper. Multi-user capacity is analyzed through calculation and simulation.
Abstract Simple sequence repeats (SSR) and random amplification of polymorphic DNA (RAPD) molecular markers were used to assess the genetic diversity of 80 isolates of Phytophthora infestans in potato ( Solanum tuberosum ) from Fujian, Heilongjiang, Hebei and Inner Mongolia Provinces in China. Polymorphism was identified by 13 SSR primers and 14 RAPD primers in the isolates of P. infestans in potato. A total of 76 bands were amplified by SSRs, with the percentage of polymorphic bands (PPB) being 78.9% and the similarity coefficient ranging between 0.00 and 0.42. A total of 189 bands were amplified by RAPDs, with the percentage of polymorphic bands being 95.2% and the similarity coefficient ranging between 0.04 and 0.66. Analysis of genetic diversity showed that there exists higher genetic variation in the Fujian population in comparison to the populations of Heilongjiang, Hebei and Inner Mongolia. Nei's genetic identity analysis indicates that the genetic similarity between populations of Heilongjiang and Inner Mongolia is the highest and that between Fujian and Hebei is the lowest. A cluster analysis revealed that isolates from Fujian, in the south of China, are distantly related to those from Heilongjiang, Hebei and Inner Mongolia in the north, and the Fujian population is distributed among more groups than the other three, exhibiting a higher genetic diversity.
Phytophthora vignae is an important oomycete pathogen causing Phytophthora stem rot on some Vigna spp. Three P. vignae isolates obtained from mung bean, adzuki bean, and cowpea exhibited high similarities in morphology and physiology but are specialized to infect different hosts. Here, we report the first de novo assembly of the draft genomes of three P. vignae isolates, which were performed using the PacBio SMRT Sequel platform. This study will extend the genomic resource available for the Phytophthora genus and provide a good foundation for further research on comparative genomics of Phytophthora spp. and interaction mechanism between hosts and pathogens.
Phytophthora capsici is a highly dynamic and destructive pathogen of vegetable and great interests on the genetic structure of P. capsici have grown in the world. However, there is little genetic information about P. capsici based on the EST-SSR markers. In this study, 193 SSR markers were developed and 33 selected markers were successfully detected and they were polymorphic with the number of alleles per locus ranging from 2 to 7. 4 SSR markers were further selected for genetic diversity analysis and Nei’s genetic diversity values of 15 populations ranged from 0.38 to 0.66, with an average of 0.53. The higher polymorphism and greater transport ability of these markers among P. capsici species were proved by the expected heterozygosity (He =0.64) and Shannon’s index of diversity (I =1.14), indicating that they maintained a substantial level of genetic diversity. Additionally, the genetic differentiation among the 4 markers (Fst =0.15) was moderate and the gene flow among groups was consequent (Nm =1.69). Clustering analyses revealed that 15 populations are made of two differentiated genetic clusters and are similar regarding genetic diversity composition. Our results suggest that there are considerable evolutionary potential of P. capsici in China and useful management strategies should be adapt to it.
Abstract Taxus chinensis is a valuable tree with uses for timber, medicinal, ornamental and landscape purposes. Most importantly, it is a source of the anti‐cancer drug paclitaxel. In 2016, needle spot disease was observed on T . chinensis in Fujian Province of China. Five isolates of similar morphology were isolated from diseased samples. The pathogen was identified as Neopestalotiopsis clavispora based on morphological and cultural characteristics and confirmed by sequence analysis of the internal transcribed spacer region (ITS) and the large subunit ribosomal RNA gene (LSU). The pathogenicity of the isolates was confirmed by fulfilling Koch's postulates. To the best of our knowledge, this is the first report to indicate that the causal agent of needle spot disease on Chinese yew in China is N . clavispora .
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