Generation of transgenic sugar beet (Beta vulgarism L.) overexpressing the polygalacturonase inhibiting protein 1 of phaseolus vulgaris (PvPGIP1) through Agrobacterium-mediated transformation

Abstract

Numerous diseases caused by fungal pathogens influence the annual production of sugar beet. In order to obtain a plant resistant to fungi, genetic transformation has been applied to the sugar beet. To invade a plant tissue, phytopathogenic fungi produce several cell wall-degrading enzymes (CWDEs); polygalacturonases (PGs) are pathogenicity factors produced at the earlier stages of a fungal infection that depolymerize the homogalacturonan. One of the strategies used by plants to limit the degradation of the cell wall polysaccharides by fungal CWDEs is the production of proteinaceous inhibitors. Against fungal, microbial, and insect PGs, plants produce cell wall-associated polygalacturonase-inhibiting proteins (PGIPs). The overexpression of PGIPs improves the resistance to fungal and bacterial necrotrophs in different plants. In this research, the gene encoding the PGIP1 fused downstream of the leader sequence for secretion in the extracellular environment was isolated from Phaseolus vulgaris and cloned into the expression vector pBI121 for the Agrobacterium-mediated transformation of sugar beet. Modified transformation protocol and selection strategies were developed. In comparison with the preexisting methods, the transformation efficiency was increased and different cultivars were transformed, highlighting the general effectiveness of the method applied. The presence of the transgene and the activity of PvPGIPl were confirmed by PCR and agarose diffusion assay analyses, respectively, and the present and copy number of the transgene in the TO plants' genome were demonstrated by Southern blot.