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.

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.

Chinese wheat mosaic virus: A long-term threat to wheat in China

In China, a soil-borne virus causing a disease of winter wheat and associated with Polymyxa graminis, has been reported for many years and is now recognized as a new species, Chinese wheat mosaic virus(CWMV). Since the determination of its genomic sequence, more progress has been made in understanding its genomic structure and functions. Molecular and serological methods have been developed to help survey the distribution of the virus and to provide the basic information needed for disease forecasting and control. At present, the best countermeasure is cultivation of resistant wheat varieties. In addition, development and application of some auxiliary countermeasures, such as rotation of non-host crops, delayed seed-sowing, reasonable application of nitrogen fertilizer, and treatment of imported seeds with fungicides before sowing, may be helpful for controlling the disease. The viral distribution and damage, virion properties, genome organization and spontaneous mutation, temperature sensitivity, and disease management options are here reviewed and/or discussed to help in developing more cost-effective countermeasures to control the disease in the future.