Heteropogon triticeus, a new host of Claviceps sorghi in India

Abstract

Claviceps sorghi occurred on Heteropogon triticeus in Gulbarga, Karnataka, India. Its external sphacelial morphology on this species differed from that on sorghum in having long white sphacelial tips that protruded from spikelets or wound around awns. The tips were formed by parallel synnema-like hyphae and were covered by a phialide layer that produced elongated macroconidia (7-18 ?m) and rounded to oval microconidia (3-5 ?m). Unlike the macroconidia, the microconidia failed to germinate. Plated macroconidia underwent secondary sporulation. The white sclerotial stroma consisted of parallel hyphae with cylindrical cells that later became rounded due to accumulation of reserve metabolites. Some of these cells differentiated into a sclerotial rind that accumulated a terracotta-coloured pigment. RAPD patterns and the rDNA nucleotide sequence confirmed the identity of the species.