Research has shown that ethylene is essential for the protection of plants against bacteria and fungi. Up until now this plant hormone was only known to be vital for the ripening of fruit. Bart Geraats from Utrecht University has demonstrated that plants which are insensitive to the hormone ethylene are hypersensitive to various microorganisms. The research implies that hortulturalists must be careful with substances that inhibit the effects of ethylene as they could increase the subseptibility to plant pathogens. It appears that ethylene plays a key role in activating the resistance mechanism of plants against infectious microorganisms. The discovery was made using modified tobacco plants, insensitive to ethylene which were shown to be more vulnerable to a wide range of pathogens. Bart Geraats Fax 0031 30 2518366 E-mail: b.p.j.geraats@bio.uu.nl www.now.nl