Morphological, Cultural, Molecular and Pathogenic Variation of Bipolaris sorokiniana in Wheat

One hundred and twenty isolates of Bipolaris sorokiniana of wheat were isolated, identified and characterized based on morphological, cultural, pathogenic and ITS (Internal Transcribed Spacer) based molecular parameters. Collected isolates differed in respect of radial mycelial growth rate, color of the colony, surface texture of the colony, shape of the colony, conidia production ability and shape and color of conidia. ITS1 and ITS4 based PCR products yielded a species-specific band of 600 bp (base pairs) on agarose gel for the confirmation of B. sorokiniana. The mycelial growth rate of the isolates ranged from 1.39 to 4.46 mm/day. The septation of conidia ranged from 1.4 to 8.6. On the basis of conidia morphology, the isolates were grouped into five different groups, whereas the isolates were grouped into 12 cultural groups based on cultural characteristics. Cultural group 8 [CG (Cultural Group)-8] was the most virulent [38.5% LAD (Leaf area diseased)] and [CG (cultural Group)-4] was the less virulent [2% LAD (Leaf area diseased)] group among 12 groups when inoculated at tillering stage of wheat cv. Kachan.

Molecular Genetic Variation in a Clonal Plant Population of Leymus chinensis （Trin.） Tzvel.

Randomly amplified polymorphic DNA （RAPD） analysis was used to investigate the genetic variation among populations, between populations, and within populations, relationships between genetic distance and geographic distance, and the molecular variation and population size. The effects of geographic and genetic distances, as well as of genetic differentiation and population size, on genetic variations of Leymus chinensis （Trin.） Tzvel. are discussed. The present study showed that there was significant RAPD variation between the Baicheng region population and the Daqing region population, with a molecular variance of 6.35% （P 〈 0.04）, and for differentiation among area populations of the Daqing region, with a molecular variance of 8.78% （P 〈 0.002）. A 21.06% RAPD variation among all 16 populations among two regions was found （P 〈 0.001）, as well as 72.59% variation within populations （P 〈 0.001）. Molecular variation within populations was significantly different among 16 populations.

Incidence,genomic diversity,and evolution of strawberry mottle virus in China

Strawberry mottle virus(SMoV)is one of the most common viruses infecting strawberries,causing losses to fruit yield and quality.In this study,165 strawberry leaf samples were collected from six provinces of China,46 of which tested positive for SMoV.The complete genome sequences of 11 SMoV isolates were obtained from Liaoning(DGHY3,DGHY16-2,DGHY17,DGHY20-2,DGHY21,DGHY26-2),Shandong(SDHY1,SDHY5,SDHY31-2,SDHY33-2),and Beijing(BJMX7).The RNA1 and RNA2 nucleotide identities between the 11 Chinese isolates were 95.4-99.3%and 96.3-99.6%,respectively,and they shared 78.4-96.6%and 84.8-93.5%identities with the available SMoV isolates in GenBank.Recombination analysis revealed that Chinese isolate SDHY33-2 and Canadian isolates Ontario and Simcoe were recombinants,and recombination events frequently occurred in the 3’UTR of SMoV.Phylogenetic analysis showed that in an RNA1 tree,most Chinese isolates clustered into the same group while isolate DGHY17 clustered into another group together with Czech isolate C and three Canadian isolates.In an RNA2 tree,all Chinese isolates clustered into a single group.The phylogenetic analysis based on nucleotide sequences was consistent with the results based on coat protein(CP)and RNA-dependent RNA polymerase(RdRp).Further evolutionary analysis indicated that negative selection drives SMoV evolution,and gene flow plays a major role in genetic differentiation.Additionally,reassortment and recombination also influence the evolution of SMoV.To our knowledge,this is the first report of the complete genome of SMoV isolates from China and a detailed analysis of the SMoV population structure.