Suppressive expression of the glutelin A1 -collagen peptide fusion in hybrid rice lines with the mutant line, Low Glutelin Content-1 (LGC-1)

摘要

A low glutelin-content mutant, LGC-1, has a mutant gene (Igcl) comprising a tail-to-tail inverted repeat of two highly homologous glutelin B genes (gluB4 and 8-gluB5), resulting in the production of double-stranded glutelin B RNA. Hybrid rice lines between LGC-1 and a trans genie line with the glutelin A1-collagen peptide fusion gene (gluAl-coll) were produced, and F_2 hybrid lines homozygous for each or both of the gluAl-coll and Igcl genes were selected. The expression of gluAl-coll in F_2 lines with Igcl was far lower than that of F_2 lines without Igcl at both the mRNA and protein levels as measured by semi-quantitative RT-PCR and immunoblotting using anti-collagen peptide antibody. The gluAl mRNA sequence alignment identical to the potential double-stranded RNA formed by gluB4 sense and 6-gluB5 antisense RNAs consisted of 14 nucleotides at most, and was not more than 23 even when one mismatch was allowed within the sequence. Thus, such shorter double-stranded glutelin B RNAs were suggested tosuppress the expression of not only endogenous gluA genes as reported previously (Kusaba et al. 2003) but also the exogenous gluAl-coll in the hybrid lines.