Resistance of Rice Varieties and Accessions to Dwarf Viruses

Identifikasi ketahanan plasma nutfah padi terhadap virus kerdil bertujuan untuk mendapatkan informasi mengenai varietas dan aksesi yang tahan terhadap virus kerdil padi, yaitu Rice ragged stunt virus (RRSV) dan Rice grassy stunt virus (RGSV). Penelitian dilakukan di Rumah Kaca Balai Besar Penelitian Tanaman Padi pada MT1/MT2 tahun 2018. Materi genetik yang diuji yaitu 19 varietas padi yang sudah dilepas dan 50 aksesi plasma nutfah padi koleksi Balai Besar Penelitian Tanaman Padi Badan Litbang Pertanian-Kementerian Pertanian. Pengamatan mengikuti metode skoring SES IRRI 2014. Respons tanaman uji terhadap RRSV dapat dikelompokkan menjadi rentan (1 varietas dan 22 aksesi), agak tahan (18 varietas dan 22 aksesi), dan tahan {2 aksesi, yaitu MDK Karawang (800 butir/Malai) (10597), dan Pulo Hitam (10615}. Respons tanaman uji terhadap RGSV dapat dikelompokkan menjadi rentan (16 varietas dan 34 aksesi), agak tahan (3 varietas dan 11 aksesi), dan tahan (1 aksesi, yaitu Ketik 1-1062). Lebih lanjut, aksesi padi yang tahan terhadap RRSV dan/atau RGSV dapat digunakan sebagai tetua dalam perakitan varietas yang tahan terhadap virus kerdil.

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>

Application of Virus-Derived Small Interfering RNAs (vsiRNAs) in Rice Viruses with Insect Vectors, Especially Rice Grassy Stunt Virus

Rice grassy stunt virus (RGSV) a member of Tenuivirus family, is very potent and destructive which effects rice crop in many countries, particularly China. Non coding RNAs have important functions in development and epigenetic regulation of gene expression in numerous organsisms. There is three type of small non coding RNAs have been found in eukaryotes, which are small interferring RNAs (siRNAs), microRNAs (miRNAs) and piwi interacting RNAs (piRNAs). Small RNAs (sRNAs) origination is from the infecting virus which is known as virus-derived small interfering RNAs (vsiRNAs), has responsibility for RNA silencing in plants. Virus-induced gene silencing (VIGS) is mainly dependent on RNA silencing (RNAi). Interestingly, RNA silencing happens in plants during viral infections. RNAi technique showed significant results in Nephotettix cincticeps. RNAi technique demonstrated the gene silencing of planthopper Nilaparvata lugens. The proteins P5, pcf4, Dnj, psn5, and pn6 act as potential movement proteins and serve as silencing suppressors for RGSV. VsiRNAs originate from dsRNA molecules which require Dicer-like (DCL) proteins, RNA dependent RNA polymerase (RdRP) proteins, and Argonaute (AGO) proteins. RdRP uses ssRNA for perfect RNA amplification process and can also be used for DCL dependent secondary vsiRNA formation. VSRs interfere with the movement of signals during silencing mechanism. Moreover, intercellular movement of viruses is facilitated by virus-encoded movement protein. RNAi is found in many eukaryotes which are related to transcriptional or post-transcriptional regulation by gene suppression. Transcription is bidirectional in ssDNA viruses which are originated from dsRNA molecules. In this review, we highlighted the biology of Rice grassy stunt virus and its insect vector and its silencing suppressors. This work will be helpful for plant virologists to understand the whole biogenesis mechanism for rice viruses especially RGSV.