PRODUCTION OF HYPHOPODIA BY WILD-TYPE AND 3 TRANSFORMANTS OF GAEUMANNOMYCES-GRAMINIS VAR GRAMINIS

Gaeumannomyces graminis var. graminis causes root and crown disease of rice and turf grasses. Its hyphae produce melanized hyphopodia (= app ressoria) on aerial plant surfaces and on plastic; the hyphopodia pres umably serve both in surviving the epiphytic portion of the life cycle and in penetrating the host. As a first step in characterizing putati ve genes and gene products associated with the induction of hyphopodia , three transformants of G. graminis var. graminis with altered hyphop odium formation were identified. According to DNA hybridization analys es, all had single insertion sites of the transforming DNA that encode s either benomyl (JH1113 and JH849) or phleomycin (JH2982) resistance. Wild-type strain JH2033 hyphopodia were pigmented and lobed. Transfor mant JH1113 hyphopodia were lobed, but more frequently produced and no t as pigmented as the wild-type. Transformant JH2982 hyphopodia were p igmented, but were less lobed and less frequently produced than in the wild-type. Transformant JH849 only rarely produced hyphopodial-like s tructures; they were pigmented but essentially lobeless. The selected strains also were affected pleiotropically in growth habit and in hyph al branching.