Co-transfer and expression of chitinase, glucanase, and bar genes in creeping bentgrass for conferring fungal disease resistance

Abstract

A construct containing a rice chitinase gene and an alfalfa glucanase gene was co-transferred with a construct containing a bar gene as a selectable marker into creeping bentgrass using microprojectile bombardment. PCR analysis confirmed the presence of bar in the genomic DNA of transformed plants. Most of the transgenic plants were consistently resistant to 0.5–4.0% Finale® (a commercial brand of herbicide glufosinate, ammonium salt of phosphinothricin). The integration of the chitinase and glucanase genes into genomes of eight lines and the bar gene into all tested lines was confirmed by Southern hybridization analyses. Northern hybridization analyses indicated that the bar gene was transcribed in 15 transgenic lines at the mRNA level and that the chitinase gene was transcribed in 5 transgenic lines, but no glucanase mRNA was detectable. The frequency of the linked co-transfer of chitinase and glucanase genes was 100%, and the frequency of the unlinked co-transfer of the bar and chitinase/glucanase genes was 50–79%. The glufosinate-resistant transgenic lines exhibited resistance to fungal pathogens, Sclerotinia homoeocarpa and Rhizoctonia solani, when 0.5% Finale® was sprayed 3 h before the pathogen inoculation. When no Finale® was applied, the five transgenic lines expressing the chitinase gene were not resistant to the pathogens.