Multiple mycoviruses identified in Pestalotiopsis spp. from Chinese bayberry.

BACKGROUND: Chinese bayberry (Myrica rubra) is a subtropical fruit crop widely grown in southern China. Twig dieback is a disease of Chinese bayberry caused by Pestalotiopsis spp. and results in great economic losses to Chinese bayberry production. A virus survey was conducted in the population of Pestalotiopsis spp. infecting M. rubra in China. We explored the viral diversity in Pestalotiopsis spp., which may provide resources for further development as biocontrol agents of twig dieback. METHODS: Strains of Pestalotiopsis spp. were isolated from diseased twigs of M. rubra, and cultured on potato dextrose agar for RNA extraction. The total RNA of each strain was extracted, mixed, and used for RNA sequencing. The resulting sequences were deduplicated, annotated, and then used for phylogenetic analysis. RESULTS: Seven novel viruses were characterized from 59 isolates of M. rubra collected from 14 localities in China. Based on the phylogenetic analysis, these viruses were classified into five viral families/orders, Botourmiaviridae, Mitoviridae, Partitiviridae, Tymovirales and Bunyavirales, and one virus, Pestalotiopsis negative-stranded RNA virus 1, which likely belongs to a new viral family. CONCLUSIONS: Metatranscriptomics analysis showed the presence of various mycoviruses in Pestalotiopsis spp. isolated from M. rubra in China. The genomes of eight putative viruses were identified, seven of which were nearly full-length. Some of these viruses of Pestalotiopsis spp. may have the potential for the biological control of twig dieback of M. rubra.

Genetic Diversity, Pedigree Relationships, and A Haplotype-Based DNA Fingerprinting System of Red Bayberry Cultivars.

High throughput sequencing was used to reveal the distribution of whole-genome variations in cultivated Morella rubra (Sieb. et Zucc.). A total of 3,151,123 SNPs, 371,757 small indels, and 15,904 SVs were detected in 52 accessions. Verification by Sanger sequencing demonstrated that the positive rate of the SNPs was approximately 97.3%. Search for more genetic variations was expanded to 141 red bayberry accessions, most of which were cultivars, by sequencing 19 selected genomic segments (SEG1-19). The results showed that each segment harbored, on average, 7.8 alleles (haplotypes), a haplotype diversity of 0.42, and a polymorphic information content (PIC) of 0.40. Seventy-two different genotypes were identified from the 141 accessions, and statistical analysis showed that the accessions with duplicated genotypes were either somatic mutants or simply synonyms. Core set selection results showed that a minimum of 34 genotypes could already have covered all the alleles on the segments. A DNA fingerprinting system was developed for red bayberry, which used the diversity information of only 8 DNA segments yet still achieved a very high efficiency without losing robustness. No large clade was robustly supported by hierarchical clustering, and well-supported small clusters mainly included close relatives. These results should lead to an improved understanding of the genetic diversity of red bayberry and be valuable for future molecular breeding and variety protection.

[Genetic diversity of Citrus succosa Hort. Ex Tanaka from seven provinces as revealed by AFLP analysis].

Using 28 selected primer combinations, 12 accessions of Bendizao tangerine from seven provinces were investigated by AFLP analysis. A total of 882 genetic sites were detected, among which 192 were polymorphic. Using Huangyan Bendizao as contrast, the polymorphic sites of the other 11 accessions from seven provinces are not very high (3.5%-10.54%), and the number of different sites between accessions from other provinces is higher than that from Zhejiang province, which indicates that the ecological difference can partially contribute the formation of the genetic diversity. Genetic distance and dendrogram showed considerably close relatedness among the 12 accessions, and the max genetic distance was 0.229. The genetic analysis of the 12 accessions from seven provinces can provide useful information for the relationship between the formation of genetic variation and environmental difference and can facilitate the genetic improvement of this cultivar.