[Fertile transgenic indica rice from microprojectile bombardment of embryogenic callus]

A reproducible and efficient transformation system for indica rice was developed based on microprojectile bombardment of embryogenic callus. Sufficient globular embryogenic calli were produced within 2-6 weeks from 3-4 week old calli derived from mature embryos. The embryogenic calli were bombarded with the plasmid pFWZ16 containing bar gene and B.t. delta-endotoxin gene. Selection, pre-regeneration, regeneration and rooting were carried out on media with 2-4 mg/L Basta. Partial desiccation treatment was used to increase the efficiency of regeneration. Transformed plantlets were recovered within 4-5 months after mature seeds were plated. From 821 bombarded embryogenic calli of two elite rice varieties popularized in South China, 477 Basta resistant plants of 48 lines were obtained. Results of PCR, Southern blotting, RNA dot blotting, and topical application of Basta demonstrated that the foreign bar gene and B.t. gene were integrated into the genome of transgenic rice plants, and also expressed. 87.5% of the transgenic plants were fertile. Mendelian segregation of the foreign genes was indicated by Basta application and Southern blot analysis of R1 plants.