Successful Control of Rice Virus Diseases
During the past ten years, plant virus laboratory (Institute of Plant Protection, JAAS) has centered on studying the interactions of virus-insect-plant (VIP), and their impacts on agriculture. To be more specific, relevant research objects are focused on rice stripe virus, rice black-streaked dwarf virus and insect vector. The researchers in the lab have published more than 80 original research articles, of which 15 published in SCI indexed journals. During this period, 12 patents have been granted.
Occurrence and Control of RSV (Rice stripe virus) in Jiangsu Province
The epidemic rice stripe virus (RSV) disease has caused severe crop losses in Jiangsu Province in the past ten years, with increased occurrence year by year since 2000. In 2004, approximately 1.57 million ha of rice (nearly 80% of the total rice fields in Jiangsu Province) were infected, and the infection resulted in a 30-40% yield loss. The outbreak was caused by a series of related factors, including the outbreak of SBPH (small brown planthopper) population, virus accumulation, a large area of susceptible rice cultivars and a warm winter, etc.. RSV is transmitted mainly by small brown planthopper (Laodelphax striatellus Fallén, SBPH) in a persistent manner, and it can also be transmitted from female adults to their progeny via eggs. Therefore, the outbreak of the disease was closely related with the outbreak of viruliferous populations of SBPH. Viruliferous rate (VR) of SBPH in the rice field was a key factor in disease epidemic.
Based on monoclonal antibodies against RSV, immunological detecting kits of RSV were successfully developed by our lab for detecting RSV in SBPH and host plant. The kits were used and extended by relevant extension professionals to detect VR of SBPH and therefore had an active role in local disease forecast. It was noticed that, when RSV was in sporadic distribution, VR of SBPH was also very low. With accumulation of virus and widespread cultivation of susceptible rice species (>80%), RSV became more severe and VR of SBPH became higher. It was the higher VR of SBPH and cultivation of susceptible rice species that led to large-scale outbreak of RSV in 2004-2005. Before the outbreak, chemical control was the primary means of prevention for RSV. During the epidemic period, apart from chemical control, rice varieties with desirable RSV resistance were developed. Since 2005, RSV-resistant varieties (>60%), vermins-proof screen and transplanter cultivation have been extended in rice production, and resulted in a declined occurrence of diseases and lower rate of VR of SBPH year by year. In recent years (since 2012), the occurrence of the diseases has been low and under control, with a VR of lower than 3%.
- Ren C, Cheng Z, Miao Q, Fan Y, Zhou Y. First report of Rice stripe virus in Vietnam. Plant disease. 2013, 97(8): 1123.
- Li S, Li X, Sun L, Zhou Y. Analysis of rice stripe virus whole-gene expression in rice and in the small brown planthopper by real-time quantitative PCR. Acta Virologica. 2012, 56(1): 67-71.
- Xiong R, Cheng Z, Wu J, Zhou Y, Zhou T, Zhou X. First report of an outbreak of Rice stripe virus on wheat in China. Plant Pathol. 2008, 57(2): 397.
- ZHOU Yi-jun,LI Shuo,CHENG Zhao-bang,ZHOU Tong,FAN Yong-jian, Research advances in rice stripe disease in China, 2012, 28(5): 1007-1015. (In Chinese)
The interactions between RSV and vector small brown planthopper
RSV is mainly transmitted by SBPH in a persistent, circulative-propagative manner. The subcellular localization of RSV in SBPH has been investigated by electron microscopy. A large number of RSV ribonucleoproteins (RNPs) distributed diffusely throughout the eggshell surface and interior of ovum, midgut lumen and epithelial cells, while the amount of the virus in muscles was far less than that in the ovary and midgut tissues. The potential mechanism of RSV transovarial transmission was proposed that the virus initially replicated and accumulated in the inclusion bodies of follicular cells, then exploited the pathway of the nutrition transportation to pass through the eggshell and spread into the oocytes. Viral interaction proteins were screened using virus overlay assay and yeast two-hybrid system, and a series of positive proteins were identified, which might be involved in propagation of RSV in vector cells. Regarding the mechanisms of SBPH acquiring virus, our ongoing study showed that RSV-NSvc2 and its receptor protein GN-Rp had positive contributions to RSV infecting and escaping from midgut barrier, which is the focus of our current research.
- Deng J, Li S, Hong J, Ji Y, Zhou Y. Investigation on subcellular localization of Rice stripe virus in its vector small brown planthopper by electron microscopy. Virol J. 2013, 10: 310.
- Li S, Xiong R, Wang X, Zhou Y. Five proteins of Laodelphax striatellus are potentially involved in the interactions between rice stripe virus and vector. PLoS One. 2011, 6(10): e26585.
- LI Shuo,SUN Li Juan,LI Xing,XIONG Ru-Yi, XU Qiu-Fang, ZHOU Yi-Ju, Construction of yeast two-hybrid eDNA library of high-viruliferous (RSV-infected)populations of the small brown planthopper, Laodelpha striatellus(Hemiptera: Delphacidae), Acta Entomologica Sinica.2011, 2011, 54(11): 1324-1328. (In Chinese)
Preliminary research on the resistances of rice varieties against two rice viruses: RSV and RBSDV
The most economical and effective approach to control the two viruses RBSDV (rice black-streaked dwarf virus) and RSV (rice stripe virus) is to identify the resistance genes and develop relevant resistant varieties.
RSV first occurred in the 1990s and broke out in large area in Eastern China in recent years. Although most japonica rice cultivars were susceptible, Zhendao 88, a japonica rice cultivar, was resistant to rice stripe disease. We found that Zhendao 88 was resistant to virus but was weakly tolerant to the SBPH using non-preference and antibiosis test. Preliminary inheritance analysis suggested that the resistance in Zhendao 88 was conditioned by a single dominant gene on the rice chromosome 11 within 4.7 cm of a simple sequence repeat (SSR) marker RM229 and a rapid amplified polymorphic DNA (RAPD) marker OPO11. RBSDV has caused serious damages in Eastern China since 2007. An RBSDV-resistant variety Tetep was identified with the development of a simple and robust method, an effective artificial inoculation for RBSDV, used to identify resistant rice germplasm. Preliminary inheritance analysis suggested that resistance observed in Tetep was conditioned by multiple loci. The qRBSDV-3 and qRBSDV-11 only for the RBSDV resistance were identified by QTL mapping using segregating populations derived from the cross between Huaidao No.5 and Tetep. Progress on the identification of user friendly genetic markers for marker-assisted selection to manage both virus diseases will be presented, which will provide useful information for developing RBSDV- and RSV-resistant rice cultivars using molecular breeding approaches.
- Zhou T, Nelson S, Hu J, Wang L, Fan Y, Cheng Z, Zhou Y. Inheritance and Mechanism of Resistance to Rice Stripe Disease in cv. Zhendao 88, a Chinese Rice Cultivar. Journal of Phytopathology. 2011, 159: 159-164.
- Zhou T, Wu L, Wang Y, Cheng Z, Ji Y, Fan Y, Zhou Y. Transmission of rice black-streaked dwarf virus from frozen infected leaves to healthy rice plants by small brown planthopper (Laodelphax striatellus). Rice Science. 2011, 18: 152-156.
- Zhou T, Wang Y, Fan Y, Cheng Z, Zhou Y. First report of rice black-streaked dwarf virus infecting barley in Jiangsu, China. Journal of Plant Pathology. 2010, 92 (4, Supplement): S4.118.
Research on RSV and RBSDV pathogenicity utilizing Arabididopsis
The pathogenesis of RSV and RBSDV and the molecular basis of plant responses to the pathogens are not well understood so that it is important to analyze interaction between virus and plants. Utilizing the “model” plant Arabidopsis, we have developed a system of biology approach to identify virus proteins or host influential factors in the pathogenesis of RSV or RBSDV.
RSV can infect Arabidopsis thaliana and causes serious disease symptoms using viruliferous SBPH. This compatible model system permits various molecular genetics and gene expression experiments to identify the defense signals and responses that inhibit RSV infection.
To investigate the role of P7-1 protein in RBSDV pathogenicity, transgenic A. thaliana plants were generated in which the P7-1 gene was expressed under the control of the 35S promoter. The RBSDV P7-1-transgenic Arabidopsis plants were male sterility. Flowers and pollen from P7-1-transgenic plants were of normal size and shape, and anthers developed to the normal size but failed to dehisce. The non-dehiscent anthers observed in P7-1-transgenic were attributed to decreased lignin content in the anthers. These results indicate that ectopic expression of the RBSDV P7-1 protein in A. thaliana causes male sterility, possibly through the disruption of the lignin biosynthesis and H2O2-dependent polymerization pathways.
- Sun F, Yuan X, Xu Q, Zhou T, Fan Y, Zhou Y. Overexpression of Rice Black-Streaked Dwarf Virus P7-1 in Arabidopsis Results in Male Sterility Due to Non-Dehiscent Anthers. PloS One. 2013, 8(11): e79514.
- Sun F, Yuan X, Zhou T, Fan Y, Zhou Y. Arabidopsis is susceptible to rice stripe virus infections. Journal of Phytopathology. 2011, 159: 767-772.