Satya Nugroho

Overexpression of RF2a in Transgenic Rice Plants Cultivar IR64 Enhances Tolerance to Rice Tungro Virus

Rice tungro disease (RTD) is one of the most important virus diseases of rice in South and Southeast Asia, which is caused by coinfection of rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). RF2a, encoding a bZIP type transcription factor, which is important for rice development is reported to bind to Box II, a crucial cis-element of the RTBV promoter and activate transcription from the RTBV promoter in infected plants. Overexpression of RF2a in transgenic rice had been reported to increase tolerance against the tungro virus. We reported the overexpression of RF2a in transgenic rice plants cultivar IR64. Bioassay using an Indonesian tungro virus isolate indicated that there was a significant increase in the tolerance of the transgenic rice lines compared to the wild-type IR64, and was comparable to the tolerant control Tukad Petanu. qRT-PCR on RF2a-overexpressed transgenic rice and the wild-type control showed that in tungro virus-infected transgenic rice plants in which weak or no RTD symptoms were observed, the relative expression of RF2a were increased. The increase in tolerance toward tungro virus was suggested due to a high level of RF2a in plants that can support rice development amid virus replication. On the contrary, in infected susceptible wild-type plants, in which the level of RF2a was low, severe RTD symptoms were observed. Thus, the availability of RF2a in tungro virus-infected IR64 plants plays an important role in determining the development of RTD symptoms.

Sequence analysis of ORF IV RTBV isolated from tungro infected Oryza sativa L. cv Ciherang

The Effort to increase rice production is often constrained by pest and disease such as Tungro. The Tungro disease is caused by the joint infection with two dissimilar viruses; a bacil-form-DNA virus, the Rice tungro bacilliform virus(RTBV) and the spherical RNA virus, Rice tungro spherical virus (RTSV) and transmitted by Green leafhopper (Nephotettix virescens). The symptom of disease is caused by the presence of RTBV. The genome of RTBV consists of four Open reading frames (ORFs) which encode functional proteins. Of the four, ORF IV is unique because it exists only in RTBV. The most efficient method of generating disease resistance plants is to look for natural sources of resistance genes in wild or germplasm and then transfer the gene and the accompanying resistance in cultivated crop varieties. The aim of this study is, therefore, to isolate and analyze of 1170 bp gene of ORF 4 of Tungro virus isolated from an Indonesian rice cultivar, Ciherang (Oryza sativa L. cv Indica). DNA sequencing analysis usin...

IDENTIFIKASI GALUR-GALUR PADI MUTANINSERSI TOLERAN DAN RENTAN CEKAMAN SALINITAS BERDASARKAN KARAKTER MULTIVARIAT PERTUMBUHAN DAN BIOKIMIA PADA FASE VEGETATIF [Identification of Salt Tolerance and Salt Sensitivity of Insertional Mutant Rice Lines Based on Multivariate Growth and Biochemical Characters at Vegetative Stage]

Growth and biochemical characters of thirty-three Nipponbare-based rice mutant lines independently harboring activation-tag in salt stress condition were investigated. Rice cv Nipponbare wild type, IR29 and Pokkali were used as isogenic, susceptible, and tolerant cultivars, respectively. Plants were grown in Yoshida nutrient solution containing NaCI (6 g/1) as the stress treatment and in Yoshida nutrient solution without NaCI as the control. Evaluation of salt tolerance was conducted at 21 days after salinization.The results showed that there was a significant difference in growth characters among genotypes in reduction of the plant height,root length, shoot fresh weight, root fresh weight, shoot dry weight, as well as in the root dry weight. Biochemical characters of the genotypes also showed significant difference in their reduction of chlorophyll-a and chlorophyll-b concentrations,total carotenoids and proline accumulation. Based on multivariate growth and biochemical characters,T3.PMO.VI.63.5a.30.9,T3.PMO.VI.30.1a.21.1, T3.PMO.V1.63.5a.33.7F3.PUR.IX.49.1d.l.6.5,T3.PMO.VI.81.3a.4.4, F3.PUR.IX.49.1d.l.6.5,and F3.PUR.VIII.5.1f.l.4.8 were assumed as potential salt-tolerant lines, respectively, while mutant lines T3.PMO.VI.30.1a.l07.7,T3.PMO.VI.63.5a.20.6,T3.PMO.III.4.4c.7.2,andT3.PMO.VI.30.1a.51.1 were assumed as salt-susceptible lines respectively.