Mating types, sex, dissemination, and possible sources of clones, of Hypomyces (Fusarium) solani, f. pisi in South Australia

Abstract

Isolates of Hypornyces (Fusarium) solani f. pisi collected in South Australia, when single-spored and cultured under the same conditions, were separable into three distinct clones.

Pairings of the three clones (SA-1, 2, and 3), and of a fourth collected in New South Wales (NSW-I), with tester clones of known mating type and sex, showed that SA-1 and SA-2 were of one mating type (+), while SA-3 and NSW-1 were of another mating type (–). SA-1 and NSW-1 were hermaphrodites; SA-2 and SA-3 functioned only as males. When SA-1 and NSW-1 were paired in reciprocal crosses, fertile perithecia developed in both cases. Fertile perithecia also developed when SA-2 and SA-3 were used as males to fertilize NSW-1 and SA-1 respectively.

A clone of H. solani f. pisi, identical with SA-1 in pathogenicity, cultural appearance, sex, and mating type, was recovered from wind-blown soil in a virgin area approximately 1 mile from a pea field but not from soil taken from districts some distance (30 miles in one case and 200 miles in another) from pea-growing districts. Other isolates identical with SA-1 in cultural appearance, mating type, sex, and pathogenicity were recovered from dust taken from a bag of non-treated, certified New Zealand pea seed imported into South Australia, from field soil collected in pea seed-producing areas of the Pacific North-west of the United States, and from England.

The occurrence of compatible clones on different continents appears to be due to an international movement of the fungus on pea seed.