Particle bombardment-mediated transformation of Malaysian rice MR 232 callus

Abstract

Rice is a staple food for more than two-third of the world’s population. As human population arises, the production of rice must also be increased via various approaches, and one of it is plant transformation. In this study, eight weeks old embryogenic callus derived from the scutellum of mature seed embryos of indica rice variety MR232 was biolistically transformed. The mature rice seed was firstly cultured on Murashige and Skoog medium supplemented with 1mg/L of 2, 4 –D and 5mg /L NAA for 8 weeks to induce callus. The callus produced showed embryogenic calli. The percentage of embryogenic calli induction was 40.7%. A white to yellowish embryogenic calli was recorded. While, in control treatment where the medium was not supplemented with any plant growth regulators, no callus induction was recorded. This embryogenic callus was then subjected to particle bombardment under room temperature. The callus of MR232 was bombarded with gold microparticles coated with plasmid pCAMGloipt harbouring the gusA gene which encodes ?-glucuronidase. Physical parameters were observed in the bombardment, which were target distance and helium pressure. After bombardment, half of the calli were subjected to GUS assay while the other half was used for PCR analysis. The histochemical GUS assay was conducted to analyse the transformation efficiency. Calli bombarded at 9cm target distance showed the highest percentage of GUS activity (recorded as blue spots) with 22.8%. While, for helium pressure parameter, calli bombarded using 900 psi of helium pressure showed the highest percentage of GUS activity with 71.43%. However, PCR analysis results no detection of GUS fragment from the bombarded calli showing that the transformation was not stable.