Species from Sorghum in Thailand.

Sorghum is the fifth most important cereal worldwide, spreading from Africa throughout the world. It is particularly important in the semi-arid tropics due to its drought tolerance, and when cultivated in Southeast Asia commonly occurs as a second crop during the dry season. We recovered from sorghum in Thailand and found , and most frequently, and intermittent isolates of and . The relatively high frequencies of and , suggest mycotoxin contamination, particularly fumonisins and moniliformin, should be evaluated. Genetic variation within the three commonly recovered species was characterized with vegetative compatibility, mating type, Amplified Fragment Length Polymorphisms (AFLPs), and female fertility. Effective population number ( ) was highest for and lowest for with values based on mating type allele frequencies higher than those based on female fertility. Based on AFLP genetic variation, the populations were the most closely related, the populations were the most distantly related, and the populations were in an intermediate position. The genetic variation observed could result if is introduced primarily with seed, while and could arrive with seed or be carried over from previous crops, , rice or maize, which sorghum is following. Confirmation of species transmission patterns is needed to understand the agricultural systems in which sorghum is grown in Southeast Asia, which are quite different from the systems found in Africa, Australia, India and the Americas.