Regeneration and Agrobacterium-mediated transformation of a popular indica rice variety, ADT39

A simple and efficient protocol for the regeneration and Agrobacterium-mediated transformation of an agronomically useful indica rice variety, ADT39 has been standardized. Initiation of callusing and its subculture were best achieved in MS medium supplemented with 300 mg/l casein enzymatic hydrolysate. The best callusing and regeneration responses were observed at concentrations of 2 mg/l 2,4-D and 1.5 mg/l BAP. Optimal transformation efficiency of 22.2% was obtained using high concentrations of augmentin as a bacteriostatic agent for a short period to inhibit the growth/ persistence of Agrobacterium, without compromising the regeneration potential of the tissue. Using a viral promoter-driven GUS reporter gene, morphologically normal fertile plants were obtained. Molecular analysis of the above transgenic plants indicated several independent, single-copy transgene insertion events. Expression of the reporter gene was detected in the above plants. Mendelian inheritance of the transgene in the progeny was also observed

RNA-interference in rice against Rice tungro bacilliform virus results in its decreased accumulation in inoculated rice plants

Rice tungro is a viral disease seriously affecting rice production in South and Southeast Asia. Tungro is caused by the simultaneous infection in rice of Rice tungro bacilliform virus (RTBV), a double-stranded DNA virus and Rice tungro spherical virus (RTSV), a single-stranded RNA virus. To apply the concept of RNA-interference (RNAi) for the control of RTBV infection, transgenic rice plants expressing DNA encoding ORF IV of RTBV, both in sense as well as in anti-sense orientation, resulting in the formation of double-stranded (ds) RNA, were raised. RNA blot analysis of two representative lines indicated specific degradation of the transgene transcripts and the accumulation of small molecular weight RNA, a hallmark for RNA-interference. In the two transgenic lines expressing ds-RNA, different resistance responses were observed against RTBV. In one of the above lines (RTBV-O-Ds1), there was an initial rapid buildup of RTBV levels following inoculation, comparable to that of untransformed controls, followed by a sharp reduction, resulting in approximately 50-fold lower viral titers, whereas the untransformed controls maintained high levels of the virus till 40 days post-inoculation (dpi). In RTBV-O-Ds2, RTBV DNA levels gradually rose from an initial low to almost 60% levels of the control by 40 dpi. Line RTBV-O-Ds1 showed symptoms of tungro similar to the untransformed control lines, whereas line RTBV-O-Ds2 showed extremely mild symptoms

Kaposi Sarcoma Herpes Virus Latency Associated Nuclear Antigen Protein Release the G2/M Cell Cycle Blocks by Modulating ATM/ATR Mediated Checkpoint Pathway

The Kaposi's sarcoma-associated herpesvirus infects the human population and maintains latency stage of viral life cycle in a variety of cell types including cells of epithelial, mesenchymal and endothelial origin. The establishment of latent infection by KSHV requires the expression of an unique repertoire of genes among which latency associated nuclear antigen (LANA) plays a critical role in the replication of the viral genome. LANA regulates the transcription of a number of viral and cellular genes essential for the survival of the virus in the host cell. The present study demonstrates the disruption of the host G2/M cell cycle checkpoint regulation as an associated function of LANA. DNA profile of LANA expressing human B-cells demonstrated the ability of this nuclear antigen in relieving the drug (Nocodazole) induced G2/M checkpoint arrest. Caffeine suppressed nocodazole induced G2/M arrest indicating involvement of the ATM/ATR. Notably, we have also shown the direct interaction of LANA with Chk2, the ATM/ATR signalling effector and is responsible for the release of the G2/M cell cycle block