First report of smut of Saccharum arundinaceum caused by Sporisorium sorghi in Yunnan, China.
In May 2009, symptoms of a disease were observed on plants of Saccharum arundinaceum at the National Nursery of Sugarcane Germplasm Resources in Yunnan Province, China, on approximately 10% of 120 plants within three germplasm collections of Saccharum arundinaceum. The initial symptom was dwarfing, resulting in spike heading 1-2 months earlier than on healthy plants. As infection progressed, the spikelet of each diseased plant became full of the black, powdery mass of fungal spores enclosed in an off-white membrane. Finally, the entire spike became severely infected. A Sporisorium sp. was isolated from diseased spike tissues. Nine fungal isolates were identified as Sporisorium sorghi based on sorus morphology, and spore morphology and colour. The preliminary morphological identification of the fungus was confirmed by PCR assay using genomic DNA extracted from the mycelia of pure cultures of each of nine isolates, which generated a 750-bp amplified region of the internal transcribed spacer (ITS) region of rDNA using ITS1/ITS4 universal primers. The ITS region was then sequenced (GenBank Accession No. JX183795), and displayed 98% similarity with the ITS sequence of an isolate of Sporisorium sorghi from Sorghum bicolor from France (AF038828.1) and Germany (AY740021.1). This is thought to be the first report of smut on Saccharum arundinaceum caused by Sporisorium sorghi in Yunnan.