Relations Among Sorghum Ergot Isolates from the Americas, Africa, India, and Australia uri icon

abstract

  • Sorghum ergot, initially restricted to Asia and Africa, was recently found in the Americas andAustralia. Three species causing the disease have been reported: Claviceps sorghi in India, C.sorghicola in Japan, and C. africana in all ergot-positive countries. The objective of our studywas to study the intraspecific variation in C. africana isolates in the Americas, Africa, India,and Australia. We confirmed C. africana, C. sorghi, and C. sorghicola as different species usingdifferences in nucleotide sequences of internal transcribed spacer 1 and 5.8S rDNA regions.Sequences of this region obtained from the representative American, Indian, and Australianisolates of C. africana were identical. In addition, random amplified polymorphic DNA (RAPD)banding patterns of sorghum ergot pathogen isolates from the United States, Mexico, PuertoRico, Bolivia, Australia, and India were evaluated with nearly 100 primers. A total of 65 primersgave identical patterns for all isolates, which confirmed that all were C. africana. The identityof RAPD pattern and rDNA sequence of Indian isolates with those of C. africana confirmedthat the species is now present in India. Only 20 primers gave small pattern differences and 7 ofthem were used for routine testing. All of the American isolates were identical and three isolatesof the same type were also found in South Africa, suggesting Africa as the origin of theinvasion clone in the Americas. Australian and Indian isolates were distinguishable by a singleband difference; therefore, migration from the Asian region to Australia is suspected. Anotherdistinct group was found in Africa. Cluster analysis of the informative bands revealed that theAmerican and African group are on the same moderately (69%) supported clade. Isolates fromAustralia and India belonged to another clade

publication date

  • 2000
  • 2000