Generation and Characterization of Transgenic Plum Lines Expressing gafp-1 with the bul409 Promoter

Abstract

The Gastrodia antifungal protein (GAFP-1) is a mannose-binding lectin that can confer increased disease resistance in transgenic tobacco and plum. In all previously generated, transgenic lines, the gene was under the control of the 35SCaMV promoter. In this study, transgenic plum lines were created from seeds derived from open pollination of the cultivar Bluebyrd (BB-OP) with gafp-1 under the control of the polyubiquitin promoter bul409 and evaluated for Phytophthora root rot (PRR) and Root knot nematode (RKN) susceptibility. One of nine transgenic lines synthesizing GAFP-1 exhibited increased tolerance to PRR caused by P. cinnamomi. The same line (BB-OP-1) was also significantly more tolerant to RKN infection caused by Meloidogyne incognita. BB-OP-1 was more resistant to PRR and equally resistant to RKN compared with the cultivar Stanley-derived 4J line, which expresses gafp-1 under the control of the 35SCaMV promoter. GAFP-1 synthesis in BB-OP-1 was not elevated by pathogen infection, suggesting that the bul409 promoter is not inducible in the plum/GAFP-1 system. This study confirms the usefulness of the gafp-1 gene in various cultivars of transgenic plum and establishes that the bul409 promoter is at least equal in effectiveness to the 35SCaMV promoter for gafp-1 expression in transgenic lines of woody plants.