Improvement of fungal disease resistance in potato using Defensin gene

Potato plants were highly susceptible to pathogenic fungi causing changes in number, character and weight of harvested tubers. The light microscopic observations showed changes in the uppermost coat thickness and texture in infected tissues with the presence of many cytoplasmic vacuoles in hypodermal and cortical layers with the presence of few starch grains in the cortical cells. Transmission electron microscopy showed cell wall and cytoplasmic changes with membrane abnormalities, in addition to dark inclusions and crystals. Multiple shoot regeneration from tuber discs and leaf explants were enhanced and were used in transformation experiments. RAPD analysis was used to detect similarities or dissimilarities between the plants. The tuber discs and leaf explants of in vitro plantlets were transformed with Agrobacterium tumefaciens. The putative lines confirmed the insertion of defensin gene and Gus reporter gene. The in vitro selected nodal cuttings exhibited resistances were acclimatized. Resistance bioassay showed absence of symptoms on transformed organs and some mild symptoms on the foliar lamina, tubers and calli of the selected lines.