Biolistic transformation of sorghum using a rice chitinase gene

A rice chitinase gene, G11, which may have a protective role against fungal pathogens, was introduced into a sorghum inbred 'Tx430'. Calli derived from immature zygotic embryos were bombarded with tungsten particles coated with a plasmid DNA containing this gene and the bar gene as a selectable marker. After transformation, six fertile transgenic plants were obtained from a total of 1,100 bombarded calli. Molecular analyses by phosphinothricin acetyltransferase (PAT) activity assay, Southern blotting, and western blotting confirmed the presence and expression of the selectable bar gene and the rice chitinase gene in primary transgenic plants (T₀). However, gene silencing occurred in a few T₀ plants at certain growth stages. Progeny analysis showed that the introduced chitinase gene was inherited and segregated among T₁ plants (progeny of selfed T₀ plants). Western blot analysis showed a 3:1 Mendelian segregation of the rice chitinase gene in T₁ progeny, suggesting that the active chitinase gene(s) was inserted in a single locus in the T₀ plants.