Detection,Occurrence,and Survey of Rice Stripe and BlackStreaked Dwarf Diseases in Zhejiang Province,China

The major viral diseases that occur on rice plants in Zhejiang Province, eastern China, are stripe and rice black-streaked dwarf diseases. Rice stripe disease is only caused by rice stripe tenuivirus （RSV）, while rice black-streaked dwarf disease can be caused by rice black-streaked dwarf fijivirus （RBSDV） and/or southem rice black-streaked dwarf fijivirus （SRBSDV）. Here we review the characterization of these viruses, methods for their detection, and extensive surveys showing their occurrence and spread in the province.

Regulation of OsPRIOa Promoter Activity by Phytohormone and Pathogen Stimulation in Rice

OsPRIOa is one of the well known pathogenesis-related genes in rice,and is induced by multiple plant hormones and pathogens.However,the underlying transcriptional regulation mechanisms in response to differe nt signals and their crosstalks are still largely unknown.In order to find new players participated in the activation of OsPRIOa,we systematically analyzed the basal expression patterns as well as the expression responses of a 2.5 kb OsPRIOa promoter in rice transgenic plants after phytohormone and pathogen stimulations.In agreement with the native gene expression,the OsPRIOa promoter can drive glucuronidase(GUS)gene expressing in spots of leaf cells,leaf trichomes,lemmas and paleae,germinating embryos,calli and root tips.The leaf expression of OsPR10a::GUS was dramatically in creased upon jasm onic acid(JA)and cytoki nin(CK)treatme nts,or challe nges of the pathogen Magnaporthe grisea and Xanthomonas oryzae pv.oryzae.Thus,the OsPRIOa promoter reported here can faithfully reflect its native gene expression.The effects of several JA and CK responsive OsWRKY genes on the regulation of OsPRIOa promoter were then inspected by luciferase transient expression assay,and the JA inducible OsWRKYlO transcription factor was found as a new positive regulator of OsPRIOa.However,the key transcription factors of JA and CK signaling pathways,OsMYC2 and B-type response regulators,were not responsible for the activation of OsPRIOa promote Our findings provided new in sights into the regulation of OsPRIOa expression during plan t-hormone/pathoge n interactions,and the OsPRIOa reporter system can be useful to unravel novel regulators from both pathogen and host.

Screening of Rice Genes Interacting with p5b of Rice BlackStreaked Dwarf Virus

Rice black-streaked dwarf virus （RBSDV） is a recognized member of the genus Fijivirus, family Reoviridae. Its genome has ten double-stranded RNA （dsRNA） segments （$1-$10）, in which the fifth genome segment （$5） contains two open reading frames （ORFs） with a partially overlapping region. The second ORF of RBSDV S5 encodes a viral nonstructural protein named p5b with unknown function. To reveal the function of p5b, its gene was ligated into the bait plasmid pGBKT7 and an expression library containing rice cDNAs was constructed using plasmid pGADT7 for yeast two-hybrid assay. The bait protein p5b was detected in yeast by western blot, and the result of an auto-activation test showed that p5b could not autonomously activate the expression of reporter genes in yeast. Then the bait protein p5b was used for screening the cDNA expression libraries of rice. Gene fragments of some pivotal enzymes involved in photosynthesis, respiration and other important metabolic processes, were identified to interact with p5b in yeast, suggesting that these interactions may play roles in symptom development in infected plants.