Interaction between the phytotoxin dothistromin and Pinus radiata embryos

Dothistromin (DOTH) is a fungal toxin occurring in Pinus radiata needles infected with Dothistroma pini. Dose-dependent toxicity of DOTH toward both P. radiata mature seed embryos and meristematic leaf callus was observed. DOTH effected 50 and 100% inhibition of embryo and leaf callus growth after absorbing 3 and 13 nmol of DOTH per g of tissue, respectively. DOTH-binding sites were localized, using immunohistology for light and electron microscopy, within small vesicles in the embryos. A 40-kDa peptide was identified in the particulate fraction of mature embryo extracts that reacted specifically with a DOTH-mouse albumin conjugate