Pollination-induced ethylene and production of 1-aminocyclopropane-1-carboxylic acid by pollen ofNicotiana tabacum cv White Burley

Tobacco (Nicotiana tabacum cv White Burley) pollen contains high levels of 1-aminocyclopropane-1-carboxylic acid (ACC; 2700 nmol/g). Such large amounts, however, do not appear until very late in the development of the anthers. Washing pollen in Kwacks medium (10% sucrose) removes nearly 40% of the pollen-held ACC. Pollination of isolated styles with washed pollen results in lower ethylene production than that of styles pollinated with unwashed pollen. No reduction in viability of washed pollen was observed in situ, although loss of viability occurred in vitro. Physical wounding of the stylar tissue induced a relatively small increase in ethylene production when compared to that induced by pollination. The results suggest that pollen-held ACC may participate in pollination-induced ethylene production in this species; however, further promotion of ethylene biosynthesis must occur in response to some other factor associated with pollination.