Abstract
Plant polygalacturonase (PG) is known to function in leaf abscisson and defense gene activation. Polygalacturonase β-subunit (PGβS) tightly associates with PG and has been proposed to interact with the catalytic subunit of PG to inhibit its activity or to prevent access of the enzyme to cell wall pectins.
We extracted proteins from tobacco leaf cell walls by treatment with LiCl. In the fraction, the amount of 42K protein slightly increased during leaf expansion. cDNA encoding the 42K protein had high similarity with tomato PGβS. The tobacco PGβS homologue gene was expressed during leaf expansion. We tried to induce silencing of the PGβS homologue gene using tomato mosaic virus-based vector, which harbored mRNA of PGβS homologue. Nicotiana benthamiana showed cell death in the inoculated leaf, and showed retarded development in upper leaf, which was speculated as silencing effect. We expect that the tobacco PGβS homologue play a role in leaf development.
