Transferring Translucent Endosperm Mutant Gene Wx-mq and Rice Stripe Disease Resistance Gene Stv-bi by Marker-Assisted Selection in Rice (Oryza sativa)

A high-yielding japonica rice variety, Wuyunjing 7, bred in Jiangsu Province, China as a female parent was crossed with a Japanese rice variety Kantou 194, which carries a rice stripe disease resistance gene Stv-b＇ and a translucent endosperm mutant gene Wx-mq. From F2 generations, a sequence characterized amplified region （SCAR） marker tightly linked with Stv-b＇ and a cleaved amplified polymorphic sequence （CAPS） marker for Wx-mq were used for marker-assisted selection. Finally, a new japonica rice line, Ning 9108, with excellent agronomic traits was obtained by multi-generational selection on stripe disease resistance and endosperm appearance. The utilization of the markers from genes related to rice quality and disease resistance was helpful not only for establishing a marker-assisted selection system of high-quality and disease resistance for rice but also for providing important intermediate materials and rapid selection method for good quality, disease resistance and high yield in rice breeding.

Effect of Rice Sowing Date on Occurrence of Small Brown Planthopper and Epidemics of Planthopper-Transmitted Rice Stripe Viral Disease

To understand the relationship between rice sowing date and occurrence of the rice small brown planthopper （SBPH） Laodelphax striatellus Fallen and the epidemics of the planthopper-transmitted rice stripe viral （RSV） disease, four sowing dates of rice were evaluated in 2006 and 2007. The results showed that the peak density of SBPH and RSV incidence in the nursery and in the transplanted field decreased with the delay of sowing date in single crop of japonica rice in north Zhejiang Province of China. The relationship between seedling RSV incidence at the end of the nursery trial with sowing date was well described by Weibull equation. The area under the curve of population dynamics （AUCPD or planthopper-day accumulation） or the peak density of the planthopper in the nursery could be summarized by a logistic equation. RSV incidence in the transplanted fields could be characterized quantitatively by a multivariate regression equation, including the variables of sowing date, peak density of the vector, and RSV incidence at the end of the nursery trial. That the descriptive model excluded the AUCPD in transplanted field implies that this variable is not necessary in forecasting disease epidemics in the field. The 2-year experiments sufficiently indicated that suitable sowing of rice could be used as one of the effective measures to control the vector population and therefore the planthopper-transmitted RSV on a larger scale. The optimal sowing date for the single-cropped transplanted japonica rice is recommended from late May to early June in north Zhejiang, China.

Disaster Prevention and Mitigation Technologies of Rice Virus Diseases Spread by Small Brown Planthopper (SBPH)

Rice stripe virus disease （RSVD） and rice black-streaked dwarf virus disease （RBSDVD） are two epidemic diseases in Yancheng City, Jiangsu Province in the last decade. The authors investigated the disaster regularity, prevention and control technology of RSVD and RBSDVD systematically. The occurrence and virus transmission of SBPH and disaster regularity of virus diseases were studied; the resistance of some rice varieties was cleared; the effects of physical and agricultural measures such as insect net blocking, appropriate late sowing and plowing on controlling occurrence and virus transmission of SBPH were figured out; a hatch of chemical agents were screened, providing efficient and harmless pesticides for effective control against SBPH and prevention against virus diseases. A set of disaster control and mitigation technologies was proposed in this paper, which was practical, sustainable, and easy to operate for the local planting patterns.