|Aoki, Takayuki - NIAR, MAFF, JAPAN|
Submitted to: Mycoscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1999
Publication Date: N/A
Interpretive Summary: Species of the filamentous fungal genus Fusarium produce toxins that contaminate food and feed and are responsible for many agronomically important diseases of cereal crops such as head scab and crown rot of wheat. This study was initiated to determine whether the major crown and root rot pathogen of wheat, Fusarium pseudograminearum, reproduces sexually through comprehensive mating experiments involving strains collected worldwide. Results of the mating experiments yielded a new species of Gibberella which we describe and illustrate as a morphologically and genetically distinct species, Gibberella coronicola. The results further indicate that G. coronicola/Fusarium pseudograminearum differs from the wheat scab pathogen G. zeae/F. graminearum with which it had been confused in the morphology of its asexual and sexual states, ecological distribution, and the plant disease symptoms it induces.
Technical Abstract: Mating experiments were performed among 18 strains of Fusarium pseudograminearum, formerly recognized as the Group 1 population of F. graminearum. Heterothallic production of perithecia was observed in eight out of all 153 possible combinations. Mature asci and viable ascospores were recovered in seven of the eight combinations. Perithecia in the fertile pairings were subglobose to ovoid, dark 120-370 um diam. and formed directly on the surface of rice stems placed on the culture media. Asci were unitunicate and 8-spored when mature. Mature ascospores were primarily hyaline, fusoid, straight, or curved, with rounded ends and (1-) 3-septate. Dimensions of the teleomorph obtained for F. pseudograminearum were different from those of the G. zeae teleomorph of F. graminearum. A new species of Gibberella, G. coronicola, is described and illustrated for the teleomorph of F. pseudograminearum. The Group 1 and Group 2 populations recognized previously within F. graminearum differ in their anamorphic and teleomorphic morphology, ecological habitats, pathogenicity, mode of sexual reproduction and phylogenetic relationships.