Rice Ragged Stunt Virus Research Articles

The microRNA399d-PHOSPHATE2 module alters rice sensitivity to rice ragged stunt virus by manipulating phosphate uptake.

Rice (Oryza sativa L.) production frequently faces threats from biotic and abiotic stressors, with rice ragged stunt virus (RRSV) as a substantial biotic factor. The relationship between inorganic phosphorus (Pi) content and susceptibility to RRSV is crucial yet poorly understood. This study investigates how phosphorus metabolism influences rice resistance to RRSV, focusing on genetic manipulations that modulate this relationship. The RRSV infection increased phosphate (Pi) content in the aerial parts of rice plants by enhancing Pi uptake and transport. Furthermore, the upregulation of microRNA399d (miR399d) and the suppression of its target gene OsPHOSPHATE2 (OsPHO2) enhanced Pi accumulation, increasing rice susceptibility to RRSV infection. Additionally, elevated Pi levels, which are associated with altered ROS dynamics, reduced ROS activity and potentially dampened the plant's innate immune response to viral infection. The miR399d-PHO2 module was identified as pivotal in mediating phosphate uptake and influencing susceptibility to RRSV through modulations in the phosphorus and ROS pathways. This study shed light on the regulatory mechanisms of phosphorus nutrition in rice, revealing a critical interaction between phosphorus metabolism, ROS dynamics, and viral defense. The findings suggest potential strategies for manipulating Pi levels to enhance plant resistance against viruses, opening avenues for agricultural improvements and disease management in rice.

Genetic Validation of Advanced Backcross-derived Rice Lines for Nilaparvata lugens (Stal) Resistance via SSR Markers

Nilaparvata lugens (Stål), referred to as the brown planthopper (BPH), is a serious threat to paddy cultivation. It inflicts damage by feeding on rice plants and serves as a vector for the rice ragged stunt virus and the rice grassy stunt virus, both of which contribute to significant yield losses. The research was conducted during kharif-2021 at Regional Agricultural Research Station (RARS), Warangal. SSR markers RM 3766 (for the Bph3 gene) and RM 586 (for the Bph4 gene) were used for molecular confirmation of resistance in BPH. The study revealed the presence of resistance genes in all resistant and moderately resistant lines, except Siddhi-BC2F6 BPH-BL-24, which was heterozygous (partial resistance) for Bph3, and Siddhi-BC2F6 BPH-BL-11 and Siddhi-BC2F6 BPH-BL-52, which were heterozygous (partial resistance) for Bph4. This genetic validation using SSR markers not only confirms the successful introgression of resistance traits but also enhances the efficiency of breeding programs aimed at developing durable BPH-resistant rice cultivars.

Molecular characterization of Rice ragged stunt virus and Rice grassy stunt virus on Rice in Gianyar, Bali, Indonesia

Rice stunt disease is one of the causes of rice harvest failure. It is caused by the infection of Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV) infection. Information about disease severity and the molecular characteristics of stunt viruses in Indonesia is still limited. Thus, this research aimed to determine the disease severity and the genetic diversity of rice stunt viruses in Gianyar, Bali. The research method consisted of observation of incidence and disease severity in the field and virus detection by reverse transcription-polymerase chain reaction (RT-PCR) using primers specific for RRSV and RGSV. The observation of the disease incidence and severity were performed in seven districts in Gianyar Regency, Bali, namely Blahbatuh, Gianyar, Payangan, Sukawati, Tampaksiring, Tegallalang, and Ubud. Stunt disease was found in all observation sites. High stunt disease incidence (> 44%) was found in three districts: Ubud, Tampaksiring, and Payangan, while the low disease incidence rate of <10% was found in Blahbatuh and Gianyar Districts. The highest stunt disease severity occurred in Tampaksiring District (60.82%), while the lowest severity occurred in Gianyar District (18.84%). The IR-64 and Ciherang cultivars are vulnerable to rice stunt disease infection. The highest homology of RRSV and RRGV nucleotides was found with Vietnam isolates being >98% and >97%, respectively. The phylogenetic analysis showed that Indonesian isolates of RRSV and RGSV were clustered in the same group as Vietnam isolates.

The immune response mechanism of Nilaparvata lugens against a combined infection of rice ragged stunt virus and Metarhizium anisopliae.

Previous studies of brown planthopper (BPH), Nilaparvata lugens, showed that carrying the plant pathogenic virus, rice ragged stunt virus (RRSV), enhanced the lethality of the entomopathogenic fungus, Metarhizium anisopliae (YTTR). The underlying mechanism for this was not established but a serine protease cascade was hypothesized to be involved. Two immune response genes, NlKPI and NlVenomase, were identified and shown to be involved. The synthesized double-strand RNA (dsRNA)techniques used in this study to explore gene function revealed that treatment with dsRNA to silence either gene led to a higher BPH mortality from M. anisopliae infection than the dsRNA control treatment. NlKPI and NlVenomase play vital roles in BPH immunity to defend against alien pathogens. Both genes participate in the immune response process of BPH against co-infection with RRSV and M. anisopliae YTTR by regulating the expression of antimicrobial peptides and phenoloxidase activity. Our study provided new targets for BPH biocontrol and laid a solid foundation for further research on the interaction of virus-insect-EPF (entomopathogenic fungus). © 2023 Society of Chemical Industry.

The immunostimulant effects of the rice ragged stunt virus genome on the growth and metastasis of breast cancer in mouse model

There are multiple treatment strategies that have been reported for breast cancer, while new and effective therapies against it are still necessary. Stimulating the immune system and its components against cancer cells is one of the unique treatment strategies of immunotherapy and long dsRNAs are immunostimulant in this regard. Based on bioinformatics approaches, a fragment of the Rice ragged stunt RNA virus genome was selected and synthesized according to its immunogenicity. Based on the in vitro transcription technique, dsRNA was synthesized and its binding ability to the PEI/PEI-Ac Polyethylenimine (PEI) or Acetylated polyethylenimine (PEI-Ac) was verified by the gel retardation assay. Then, the PEI-Ac was synthesized by adding acetyl groups to the PEI, and the results of the 1H NMR method indicated its successful synthesis. After cancer induction by 4 T1 cells in Balb/C mice, intraperitoneal (IP) and intratumoral (IT) treatment by the PEI/PEI-Ac-dsRNA were performed and the tumor growth inhibition was evaluated. Results demonstrated that PEI/PEI-Ac-dsRNA can lead to a decrease in tumor weight and volume in both the IP and IT routes. Also, by using macro-metastatic nodule counting and hematoxylin and eosin (H&E) staining we showed that PEI/PEI-Ac-dsRNA can prevent micro and macro-metastasis in the lung. Therefore, the PEI/PEI-Ac-dsRNA acts as an effective inhibitor of growth and metastasis of the breast cancer models. We showed that viral dsRNA can exert its antitumor properties by stimulating TNF-α and IFN-γ. In general, our results revealed that dsRNA derived from the plant virus genome stimulates the intrinsic immune system and can be a potential immune stimulant drug for cancer treatment.

RT-RPA-PfAgo System: A Rapid, Sensitive, and Specific Multiplex Detection Method for Rice-Infecting Viruses.

The advancement in CRISPR-Cas biosensors has transmuted the detection of plant viruses owing to their rapid and higher sensitivity. However, false positives and restricted multiplexing capabilities are still the challenges faced by this technology, demanding the exploration of novel methodologies. In this study, a novel detection system was developed by integrating reverse transcriptome (RT) techniques with recombinase polymerase isothermal amplification (RPA) and Pyrococcus furiosus Argonaute (PfAgo). The RT-RPA-PfAgo system enabled the simultaneous detection of rice ragged stunt virus (RRSV), rice grassy stunt virus (RGSV), and rice black streaked dwarf virus (RBSDV). Identifying targets via guide DNA without being hindered by protospacer adjacent motif sequences is the inherent merit of PfAgo, with the additional advantage of it being simple, cost-effective, and exceptionally sensitive, with detection limits between 3.13 and 5.13 copies/µL, in addition to it effectively differentiating between the three distinct viruses. The field evaluations were also in accordance with RT-PCR methods. The RT-RPA-PfAgo system proved to be a robust, versatile, highly specific, and sensitive method with great potential for practicality in future plant virus diagnostics.

Bioecology and Management of Major Insect Pests of Rice in West Bengal

West Bengal is considered a large producer state of rice in India with an output of nearly 55.48% of total crop production of Bengal. In West Bengal, rice has grown in three different cropping seasons such as Aus (autumn rice), Aman (winter rice) and Boro (summer rice), contributing about 20.69% to the total net State Domestic Product (SDP). Rice production in West Bengal hampered by many biotic stresses mostly by stem borers [Scirphophaga incertulas (Walker, 1863), Sesamia inference (Walker, 1856), Chilo polychrysus (Meyrick, 1932), Chilo suppressalis(Meyrick, 1863)] leaf folder [Cnaphalocrocis medinalis (Guenee, 1854)], plant hoppers [Nilaparvata lugens(Stal, 1854), Sogatella furcifera (Horvath, 1899)], leaf hoppers [Nephotettix virescens (Distant, 1908), Nephotettix nigropictus (Stal, 1870)], rice hispa [Dicladispa armigera (Olivier, 1808)], rice bugs [Leptocorisa acuta (Thunberg, 1783), Leptocorisa oratorius (Fabricius, 1794), Brevennia rehi (Lindinger, 1943)], gall midge [Orseolia oryzae (Wood-Mason, 1889)], etc. Demographic parameter has shown that rice pests are greatly affecting rice host either caused directly by creating dead heart (DH), hopperburn, onion leaf, silver shoot during different stages of harvesting or by indirectly transmitting grassy stunt virus (RGSV), rice ragged stunt virus (RRSV), rice tungro viruses (RTV), rice tungro bacilliform virus (RTBV) etc. resulting 9.5% production loss. For minimize the infestation farmers use different rice varieties which provide resistance effect in pest population. For controlling rice pest population farmers mostly use chemical insecticide [e.g. fipronil, acephate, fipronil, monocrotophos] which exhibit good results against rice pests. Beside those other techniques including using biological and biochemical pesticides [neem oil, karanj oil, mahua oil, conidial suspension of M. anisopliae], pheromones [(Z)-11-hexadecinal, (Z)-9-hexadecenal], allomones [5: 1 mixture of 2-(E)-octenyl acetate and octanol 3-octenal], cultutal methods [synchronized planting, using of trap crop etc.] are effective for controlling rice pests. The population ecology based sustainable management of such pest species will support E 3 strategy [Ecosystem service-based ecological engineering for ecological pest management (ESS-EE-EPM)] of pest management for successful cultivation of rice in the near future.

Incidence of dwarf disease and yield on Inpari 32 over two sequential seasons in Klaten, Central Java

Rice dwarf disease caused by Rice grassy stunt virus (RGSV) and Rice ragged stunt virus (RRSV) is frequently found in Indonesia. This disease is transmitted by brown planthopper/BPH (Nilaparvata lugens Stål). The infected plants become dwarfs and lead to reduced yields. The purpose of this study is to determine the number of BPH populations due to the occurrences of dwarf disease and yield on Inpari 32 rice over two sequential planting seasons in Klaten, Central Java. The observed parameters were dwarf disease symptoms, incidence and intensity of the disease, BPH population and its natural enemy, the vegetative growth, and yields. The analysis used in this study were descriptive analysis and linear regression. The results showed that, plant growth during the dry season was better than the rainy season based on plant height and tiller number. The average population of BPH in the dry season were 0.2–4 individual/hill which is lower than in the rainy season (0.43–4.4 individual/hill). The incidence and intensity of disease in the dry season were lower than rainy season. The higher incidence and intensity of rice dwarf disease in the rainy season caused a decrease in dry harvest yields and milled dry yields were 10.95% and 10.81%, respectively

Immune Responses and Transcriptomic Analysis of Nilaparvata lugens against Metarhizium anisopliae YTTR Mediated by Rice Ragged Stunt Virus.

Plant viruses and entomopathogenic fungi (EPF) can both elicit immune responses in insects. This study was designed to clarify whether plant viruses could affect the efficacy of EPF and explore the immune responses of brown planthopper (BPH), Nilaparvata lugens, in response to different pathogen infections. In this study, a strain of Metarhizium anisopliae YTTR with high pathogenicity against BPH was selected and explored whether rice ragged stunt virus (RRSV) could affect its lethality against BPH. RNA-seq was used to detect the inner responses of BPH in response to RRSV and M. anisopliae YTTR infection. Results showed that M. anisopliae YTTR has strong lethality against BPH (RRSV-carrying and RRSV-free). RRSV invasion did not affect the susceptibility of BPH against M. anisopliae YTTR at all concentrations. At 1 × 108 spores/mL, M. anisopliae YTTR caused a cumulative mortality of 80% to BPH at 7 days post-treatment. The largest numbers of differentially expressed genes (DEGs) was obtained in BPH treated with the two pathogens than in other single pathogen treatment. In addition, KEGG enrichment analysis showed that the DEGs were mostly enriched in immune and physiological mechanisms-related pathways. Both RRSV and M. anisopliae YTTR could induce the expression changes of immune-related genes. However, most of the immune genes had varying expression patterns in different treatment. Our findings demonstrated that RRSV invasion did not have any significant effect on the pathogenicity of M. anisopliae YTTR, while the co-infection of M. anisopliae YTTR and RRSV induced more immune and physiological mechanisms -related genes' responses. In addition, the presence of RRSV could render the interplay between BPH and M. anisopliae YTTR more intricate. These findings laid a basis for further elucidating the immune response mechanisms of RRSV-mediated BPH to M. anisopliae infection.

The effect of migration on transmission of Wolbachia in Nilaparvata lugens.

Brown planthopper Nilaparvata lugens, which can transmit rice ragged stunt virus, is a serious and damaging pest to rice plants. Rice plants can protect themselves from the associated diseases of N.lugens by either suppressing or replacing N.lugens by releasing N.lugens infected by a special strain of Wolbachia wStri. The long-distance migration habit of N.lugens is one of the important precursors leading up to the large-scale occurrence of N.lugens. To study the effect of migration on the transmission of Wolbachia in N.lugens, a Wolbachia spreading dynamics model with migration of N.lugens between two patches is put forward. The existence and local stability conditions of equilibrium points of the system and its subsystems are obtained. Moreover, the effects of migration on the dynamic properties and the control of N.lugens are analyzed; the results show that the system can exhibit a bistable phenomenon, and the migration can change the stability of equilibrium infected with wStri from stable to unstable. The quantitative control methods for the migration of the insect N.lugens are proposed, which provide a theoretical guidance for future field experiments. Lastly, we use the Markov chain Monte Carlo (MCMC) method to estimate the parameters of the wild N.lugens migration model based on limited observational data; the numerical simulation results show that migration can increase the quantity of N.lugens, which is consistent with the relevant experimental results.

Analysis of impulse release of Wolbachia to control Nilaparvata lugens

Brown planthopper Nilaparvata lugens is a serious rice damaging pest and can transmit rice ragged stunt virus. A new biological control method for Nilaparvata lugens by using Wolbachia wStri has been successful in the laboratory. No matter using the strategy of population replacement or the strategy of population suppression to release Nilaparvata lugens infected with wStri, theoretical analysis shows that Nilaparvata lugens infected with wStri may eventually disappear after interacting with the wild Nilaparvata lugens, so the Nilaparvata lugens infected with wStri should be released several times. The question is when and how much to release. In this paper, we propose a population replacement model and a population suppression model with state-dependent impulse release. The existence and stability conditions of the corresponding periodic solutions for these two systems are obtained by applying the theory of semi-continuous dynamical system. We found that the defined evaluation index of wStri release time determines the property of the solutions of the systems. The growth period of Nilaparvata lugens infected with wStri is divided into several stages according to the evaluation index of wStri release time, and the release measures for different stages are put forward, especially the release strategy to make the wild Nilaparvata lugens extinct is discussed. Based on the concept of control degree, a more realistic control goal is also discussed, which is to keep the wild Nilaparvata lugens under a lower level within a finite time. Numerical simulation shows that the effective control has good robustness to the biological parameters of insect, and both strategies can effectively control the wild Nilaparvata lugens.

The Infectivity Survival and Transmissibility of Rice ragged stunt virus from the Frozen-Infected Rice Leaves by the Brown Planthopper, Nilaparvata lugens Stål

Rice ragged stunt virus, which was transmitted by the brown planthopper (Nilaparvata lugens Stål), was an economically important rice plant pathogen, and caused the yield losses of 10 - 100 % in Thailand and Asian rice cultivation areas. The purpose of this research was to assess the infectivity survival and the transmissibility of Rice ragged stunt virus from the frozen infected rice leaf tissues to the hosts, and the efficiency detection by the indirect enzyme-linked immunosorbent assay on nitrocellulose membranes. The result was shown that rice virus was successfully acquired from the infected rice leaf frozen samples at –20 °C (7 days and 10 months) by the insect vectors, which the reactions can be clearly detected on the nitrocellulose membranes. The efficiencies of the insect vector inoculated, and the rice plant transmitted were 60 - 100 % and 20 - 100 %, and the direct variations with increasing of the viral-minimal latent period at the 3 and 10 days after inoculation, respectively. The maximum efficiency detection of crude sap sample dilutions of both viral hosts in the insect vector and the rice plant were the 1:16 to 1:64, and 1:64 to 1:256, respectively. These new idea transmission methods can be applied for the long-term stability, viability and infectivity of the infected samples, the laboratory protocol development of the cryopreservation techniques for the future study purpose of a plant virus, the viral-resistance breeding process, and the impose rice plant protection policies and strategies in Thailand.
 HIGHLIGHTS
 
 Rice ragged stunt virus (RRSV) causes the most destructive rice plant viral disease in Thailand irrigational rice cultivation
 The brown planthopper (BPH) is an economically important vector and a serious management problem for Thai farmers
 The infected rice leaf samples under the frozen and refrigeration conditions were successful as active reservoirs for the viral cycle and transmission
 The RRSV-minimal latent periods (MLP) of the BPH vector and the rice plant were 3 and 10 days after inoculation
 Understanding of plant-virus-vector interactions can take to improve the ability to insect and rice viral disease control policies and strategies in the agro-ecosystem
 
 GRAPHICAL ABSTRACT

Rice ragged stunt virus (rice ragged stunt)

Rice ragged stunt virus (rice ragged stunt)

Resistance Evaluation of Some Rice Varieties by Feeding Activity of Brown Planthopper Population in Java

Brown Planthopper (BPH), Nilaparvata lugens Stal (Hemiptera: Delpachidae) is the important pest of rice. The infestation of BPH reduced the rice yield on rice producer countries in Asia. In Indonesia, the area of BPH infestation frequently fluctuated over the year. BPH directly caused hopper burn and also vector of rice grassy stunt virus (RGSV) and rice ragged stunt virus (RRSV). This study aimed to evaluate the resistance of some rice varieties to different BPH population in Java. Three BPH populations collected from Karawang (West Java), Pekalongan (Central Java) and Kendal (Central Java) were used in this study. The rice resistance was evaluated by conducting honeydew test. There were eight rice varieties tested i.e Sembada 168, Ciherang, Inpari 32, Inpari 33, IR 64, TN1, Ratu Heenati and PTB 33 with five replications. A number of 200 female adults (five females per plot) were starved for 2 hours before inserting to pot containing one seedling. The BPH adults were allowed to feed 40-day-old plants for 48 hours. The area of honeydew excreted by BPH was measured using software Image J. We used analysis of variance (ANOVA) and cluster analysis with ward method and similarity index of Euclidean distance to analyze the rice resistance to BPH. The study indicated three groups of rice resistance level. The variety of Sembada 168 and TN1 were susceptible to BPH. Variety of Ciherang, Inpari 32, Inpari 33 and IR 64 were moderately resistant to BPH. However, PTB 33 and Ratu Heenati were strongly resistant to BPH population of Java.

Optimized RNA-Silencing Strategies for Rice Ragged Stunt Virus Resistance in Rice.

Rice ragged stunt virus (RRSV) is one of the most damaging viruses of the rice culture area in south and far-eastern Asia. To date, no genetic resistance has been identified and only expensive and non-environmentally friendly chemical treatments are deployed to fight this important disease. Non-chemical approaches based on RNA-silencing have been developed as resistance strategies against viruses. Here, we optimized classical miRNA and siRNA-based strategies to obtain efficient and durable resistance to RRSV. miRNA-based strategies are involved in producing artificial miRNA (amiR) targeting viral genomes in plants. Classically, only one amiR is produced from a single construct. We demonstrated for the first time that two amiRs targeting conserved regions of RRSV genomes could be transgenically produced in Nicotiana benthamiana and in rice for a single precursor. Transgenic rice plants producing either one or two amiR were produced. Despite efficient amiR accumulations, miRNA-based strategies with single or double amiRs failed to achieve efficient RRSV resistance in transformed rice plants. This suggests that this strategy may not be adapted to RRSV, which could rapidly evolve to counteract them. Another RNA-silencing-based method for viral resistance concerns producing several viral siRNAs targeting a viral fragment. These viral siRNAs are produced from an inverted repeat construct carrying the targeted viral fragment. Here, we optimized the inverted repeat construct using a chimeric fragment carrying conserved sequences of three different RRSV genes instead of one. Of the three selected homozygous transgenic plants, one failed to accumulate the expected siRNA. The two other ones accumulated siRNAs from either one or three fragments. A strong reduction of RRSV symptoms was observed only in transgenic plants expressing siRNAs. We consequently demonstrated, for the first time, an efficient and environmentally friendly resistance to RRSV in rice based on the siRNA-mediated strategy.

Characterization of taro reovirus and its status in taro (Colocasia esculenta) germplasm from the Pacific.

Taro reovirus (TaRV) has been reported infecting taro (Colocasia esculenta) in the South Pacific, but information on the virus is limited. Here, we report the genome sequence of a reovirus infecting taro in Papua New Guinea that had 10 genomic segments ranging from 1.1 to 3.9 kilobase pairs (kbp) in length with a total genome length of 26.3 kbp. TaRV was most closely related to rice ragged stunt virus (RRSV) but did not cross-react with RRSV polyclonal antisera. TaRV was not detected in 82 germplasm accessions of taro in Hawaii, or samples collected in American Samoa, Fiji, Guam, Palau, or Vanuatu.

Transmission Effectivity of Rice Yellow Stunt Disease by Imidacloprid-Resistant and Susceptible Brown Plant Hopper

The brown plant hopper (BPH) is a major pest of rice and as a vector of Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV). Curently, numerous rice yellow stunt disease symptoms are found in the field that caused by the single and simultaneous infection of these two viruses. Brown plant hopper population correlate with the incidence and severity of the disease. Misuse of insecticides, would cause of BPH resistances to imidacloprid. This study aimed to investigate the ability of BPH imidacloprid-resistant and susceptible to transmit of rice yellow stunt disease on rice plants. The variables tested were the acquisition period, inoculation period, number of infesting BPH, and lifespans of the viruliferous BPH that used in this research. Experiments were set as separated Completely Randomized Design with 10 replications for each treatment within an experiment. The results showed that both resistant and susceptible BPH to imidacloprid was able to transmit the virus to healthy plants. The acquisition and inoculation period test showed the BPH could transmit the virus with the shortest acquisition time for 30 minutes followed 24 hours of inoculation, as well as the acquisition time of 10 days with the shortest inoculation time for 30 minutes. Based on the incubation time, symptoms variation, and disease severity, susceptible BPH were more effective in transmitting rice yellow stunt disease than imidacloprid-resistant BPH. Single imidacloprid-resistant or susceptible BPH was proven able to transmit rice yellow stunt disease to healthy plants during its lifespan. Lifespans BPH viruliferous of imidacloprid-resistant were shorter than susceptible, which was 16 days for resistant BPH and 21 days for susceptible BPH.

Wolbachia spreading dynamics in Nilaparvata lugens with two strains

The Nilaparvata lugens is primary vector of rice diseases such as rice ragged stunt. A recent study reported the Wolbachia wStri can cause the cytoplasmic incompatibility of N.lugens, and inhibit the infection and transmission of rice ragged stunt virus in the laboratory. In this work, based on multi-strains infection mechanisms including incomplete cytoplasmic incompatibility and imperfect maternal transmission, we use differential equations to describe the spreading dynamics of Wolbachia wStri and wLug in N.lugens population. The system can exhibit one or two stable equilibria. The stability of equilibrium infected with wStri shows that wStri can invade wild populations when the cytoplasmic incompatibility intensity of wStri and the maternal inheritance leakage rate of wLug are higher than some certain thresholds. The stability conditions of the equilibria are related to the mutual fitness of the populations. If one population is more adaptable than the other, it will be in the ascendancy. An initial value region is found, from which the trajectory of system tends to the equilibrium infected with wStri. Studies on subsystem without wStri demonstrate there is a symbiotic relation between Wolbachia wLug and N.lugens population, and Wolbachia wLug can promote the reproduction of N.lugens. In addition, our numerical results are consistent with relevant literatures experimental results. Our results can guide the release of N.lugens infected with wStri in rice fields to control the growth of wild N.lugens population.

Stable Introduction of Plant-Virus-Inhibiting Wolbachia into Planthoppers for Rice Protection

Progress has been made in developing the maternally inherited endosymbiotic bacterium Wolbachia as a tool for protecting humans from mosquito-borne diseases. In contrast, Wolbachia-based approaches have not yet been developed for the protection of plants from insect pests and their associated diseases, with a major challenge being the establishment of artificial Wolbachia infections expressing desired characteristics in the hemipterans that transmit the majority of plant viruses. Here, we report stable introduction of Wolbachia into the brown planthopper, Nilaparvata lugens, the most destructive rice pest that annually destroys millions of hectares of staple crops. The Wolbachia strain wStri from the small brown planthopper, Laodelphax striatellus, was transferred to this new host, where it showed high levels of cytoplasmic incompatibility, enabling rapid invasion of laboratory populations. Furthermore, wStri inhibited infection and transmission of Rice ragged stunt virus and mitigated virus-induced symptoms in rice plants, opening up the development of Wolbachia-based strategies against major agricultural pests and their transmitted pathogens. VIDEO ABSTRACT.

Genetic Variability and Heritability of Green Super Rice (GSR) Lines Resistance to Rice Ragged Stunt Virus (RRSV) and Rice Grassy Stunt Virus (RGSV)

<p>Brown plant hopper (BPH) is one of the main pest of rice in Indonesia and it occurred every years with fluctuate acreage. BPH is also vector of Rice Ragged Stunt Virus (RRSV) and Rice Grassy Stunt Virus (RGSV). Green Super Rice (GSR) was designed to have resistance to major pests and diseases so that it need less pesticides and thus save ro environment. GSR was developed in IRRI and China and was tested in Indonesia since 2009 until now (2019). This research was aimed to study the genetic variability and heritability of 26 selected GSR lines to RRSV and RGSV along with four check varieties. The experiment was conducted in ICRR Sukamandi and Pusakanagara Experimental Station. The experiment was arranged following randomized complete block design with three replications. Transplanting was done into 21 days old seedling into 25 cm x 25 cm planting space of 1 m x 1 m plot. BPH and virus investation was occured narturally due to BPH outbreak along the season (DS 2010). Percentage of plant showing RRSV and RGSV symtom was measured as consideration the resistance of plant to the viruses. The results showed that the tested genotypes had high genetic variability and heritability classified as medium in the resistance to RGSV. The genotypes showed low genetic variability and heritability in the resistance to RRSV. It implies that breeder effort is feasible to develop resistant lines to RGSV. HUANGHUAZHAN and HHZ 12-Y4-Y3-Y1 are consistently resistant to RGSV and can be used as donors in further plant breeding activities. The selection of resistant individuals in populations of plant breeding material recommended to be done on earlier generations for RGSV and further generation for RSSV.</p>