An effective strain of Frankia from Casuarina sp.

Abstract

A strain of Frankia, designated Cj1-82, from root nodules of a hybrid of Casuarina junghuhniana and C. equisetifolia has been isolated in pure culture. When grown under standard culture conditions, Cj1-82 exhibited the following characteristics: cushionlike colonies with short, wide hyphae and, in addition to typical sporangia, intercalary elongated sporangialike structures (SLS) which could be disrupted into sporelike units. No vesicles were found. When inoculated into the rhizosphere of C. equisetifolia, Cj1-82 produced vesicles. Reinfection of seedlings of C. equisetifolia was achieved repeatedly with inocula prepared from a suspension of Cj1-82. Sequences of infection of root hairs were described. Fourteen days after inoculation, nodules were apparent on the roots. Nodules were shown to be effective in nitrogen fixation as assessed by the acetylene-reduction technique.