Protoplast responses in the epidermis of Allium cepa induced by penetration by Botrytis allii

Penetration of Allium cepa epidermal calls (white, yellow, and red varieties) by Botrytis allii induced a response by host protoplasts in normal tissue which was not observed when penetrations were made in protoplast-free host cell walls. Callose and auto-fluorescing substances (possibly phenolic compounds) were located at the penetration sites only in normal host cells containing protoplasts. Lignin test were negative. Halos were clearly visible in both types of tissue. Auto fluorescence was observed at penetration sites in normal cells of all cultivars but general wall background autoflorescence was not observed in white onions. Autofluorescence was generally yellow green and when treated with ammonium hydroxide became green.