Conidial morphology and ecological characteristics as diagnostic tools for identifying Claviceps purpurea from salt-marsh habitats

• Published in: Canadian journal of plant pathology Vol. 27; no. 3; pp. 389 - 395
• Main Authors: Fisher, A.J, DiTomaso, J.M, Gordon, T.R
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.09.2005
• Subjects: cereal grains; Claviceps purpurea; conidia; conidial morphology; ergot; fungal anatomy; geographical variation; grasses; habitats; host plants; pathogen identification; plant pathogenic fungi; salt marshes; salt-marsh habitats; Spartina; strain differences
• ISSN: 0706-0661; 1715-2992
• DOI: 10.1080/07060660509507237

Claviceps purpurea associated with grass hosts in salt-marsh habitats, also known as G3 ergot, can be differentiated from C. purpurea infecting grasses in other habitats, using genetic, chemical, and morphological criteria. However, only morphological analysis can be preformed on herbarium specimens, which should not be destroyed, or older samples that cannot be grown in culture. To determine if conidial characteristics could be employed to identify the three infraspecific groups of C. purpurea (G1-G3), sclerotia from terrestrial grasses (G1), moist habitats (G2), and salt-marsh habitats (G3) were examined. All G1 sclerotia sank in water. All G3 sclerotia floated in water, except those from Washington State, which had variable buoyancy characteristics. Group 2 sclerotia did not float in water, except those collected from Calamagrostis nutkaensis and Ammophila breviligulata. Based on the length of conidia derived from a plant host, G1 samples are indistinguishable from G2 samples but are significantly different from G3. Conidia produced in culture were on average smaller than conidia produced on plant hosts. These results indicate that ecological and conidial characteristics can be used to distinguish G3 from G1, but cannot consistently separate either from G2.