Development of Molecular Markers Tightly Linked to Pvr4 Gene in Pepper Using Next-Generation Sequencing

It is imperative to identify highly polymorphic and tightly linked markers of a known trait for molecular marker-assisted selection. Potyvirus resistance 4 (Pvr4) locus in pepper confers resistance to three pathotypes of potato virus Y and to pepper mottle virus. We describe the use of next-generation sequencing technology to generate molecular markers tightly linked to Pvr4. Initially, comparative genomics was carried out, and a syntenic region of tomato on chromosome ten was used to generate PCR-based markers and map Pvr4. Subsequently, the genomic sequence of pepper was used, and more than 5000 single-nucleotide variants (SNVs) were identified within the interval. In addition, we identified nucleotide binding site–leucine-rich repeat-type disease resistance genes within the interval. Several of these SNVs were converted to molecular markers desirable for large-scale molecular breeding programmes

Simultaneous Mutations in Multi-Viral Proteins Are Required for Soybean mosaic virus to Gain Virulence on Soybean Genotypes Carrying Different R Genes

BACKGROUND: Genetic resistance is the most effective and sustainable approach to the control of plant pathogens that are a major constraint to agriculture worldwide. In soybean, three dominant R genes, i.e., Rsv1, Rsv3 and Rsv4, have been identified and deployed against Soybean mosaic virus (SMV) with strain-specificities. Molecular identification of virulent determinants of SMV on these resistance genes will provide essential information for the proper utilization of these resistance genes to protect soybean against SMV, and advance knowledge of virus-host interactions in general. METHODOLOGY/PRINCIPAL FINDINGS: To study the gain and loss of SMV virulence on all the three resistance loci, SMV strains G7 and two G2 isolates L and LRB were used as parental viruses. SMV chimeras and mutants were created by partial genome swapping and point mutagenesis and then assessed for virulence on soybean cultivars PI96983 (Rsv1), L-29 (Rsv3), V94-5152 (Rsv4) and Williams 82 (rsv). It was found that P3 played an essential role in virulence determination on all three resistance loci and CI was required for virulence on Rsv1- and Rsv3-genotype soybeans. In addition, essential mutations in HC-Pro were also required for the gain of virulence on Rsv1-genotype soybean. To our best knowledge, this is the first report that CI and P3 are involved in virulence on Rsv1- and Rsv3-mediated resistance, respectively. CONCLUSIONS/SIGNIFICANCE: Multiple viral proteins, i.e., HC-Pro, P3 and CI, are involved in virulence on the three resistance loci and simultaneous mutations at essential positions of different viral proteins are required for an avirulent SMV strain to gain virulence on all three resistance loci. The likelihood of such mutations occurring naturally and concurrently on multiple viral proteins is low. Thus, incorporation of all three resistance genes in a soybean cultivar through gene pyramiding may provide durable resistance to SMV

Characterization and comparison of French and Brazilian Potato virus Y (PVY) isolates collected from PVY-susceptible or -resistant tobacco plants carrying the recessive resistance gene va

International audienc

Brazilian Potato virus Y isolates identified as members of a new clade facilitate the reconstruction of evolutionary traits within this species

[EN] Potato virus Y (PVY) is a plant virus distributed worldwide that causes damage to several species of the Solanaceae family. It was established long ago that groups of PVY isolates defined by phylogenetic analyses correlate strongly with those demarcated by differential biological properties. Consequently, life-history traits of this viral species can be inferred by phylogenetic analysis. In this study, characteristics of PVY isolates sampled in different tobacco fields in Brazil were analysed and most of the tested Brazilian PVY isolates were assigned to the recently described unconventional serogroup Y-U. The analysis of molecular diversity of the coat protein (CP) cistron from some Y-U isolates made it possible (i) to identify specific amino acid residues in the N-terminal of the CP protein and (ii) to assign some Y-U isolates to a new PVY clade. The symptoms caused by isolates belonging to this new PVY Brazilian' clade and their ability to infect selected susceptible hosts led to the conclusion that neither veinal necrosis symptoms expressed on infected tobacco plants nor adaptation to potato or pepper hosts are ancestral characteristics of PVY. These observations suggest that PVY has gained a remarkable new biological property and broadened its host range over time.The authors wish to thank Claudir Lorencetti (Alliance One from Brazil) who kindly supplied tobacco PVY isolates. Transfer of materials from Brazil to France was carried out using an official letter of authorization 'LOA' delivered to L. Glais (INRA Rennes/FNPPPT Paris) by plant protection organizations. The authors gratefully acknowledge Dr Alain Palloix (INRA, Avignon) who kindly provided pepper seeds for the host range study and Maryse Guillet (FN3PT, Le Rheu) who kindly provided serum for PVY DAS-ELISA. A. W. and S. F. E. were supported by grants BFU2012-30805 from Spanish MINECO and 22371 from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. J. M. C. was supported by the JAE-Doc program from CSIC. This study was supported by The Imperial Tobaccos Group and the Association for Research on Nicotianae (ARN).Janzac, B.; Wilemsem, A.; Cuevas, JM.; Glais, L.; Tribodet, M.; Verrier, J.; Elena Fito, SF.... (2015). Brazilian Potato virus Y isolates identified as members of a new clade facilitate the reconstruction of evolutionary traits within this species. Plant Pathology. 64(4):799-807. https://doi.org/10.1111/ppa.12318S79980764