New host range and distribution of Ceratocystis pirilliformis in South Africa

Ceratocystis pirilliformis was first described from wounds on Eucalyptus trees in Australia and subsequently found as a common wound inhabitant on these trees in South Africa. During a recent disease survey carried out to identify Ceratocystis species infecting tree wounds in South Africa, C. pirilliformis was isolated from various tree species, including a native Rapanea species and two non-native hosts, Acacia mearnsii and E. grandis growing in the Western Cape Province. These new collections from the Western Cape Province, together with isolates of C. pirilliformis previously collected from Eucalyptus species in the eastern part of the country, provided the opportunity to investigate the possible movement of the pathogen since it was first recorded in South Africa. The identity of newly collected isolates of C. pirilliformis was confirmed using DNA sequence comparisons using partial β-tubulin and TEF-1α gene regions. Microsatellite markers were screened on a collection of C. pirilliformis isolates from the Western Cape Province. Results showed that this population has higher levels of population genetic estimates such as private allele frequency, allelic richness and gene diversity. Inoculation tests were performed to determine whether C. pirilliformis is a pathogen of A. mearnsii, which is planted as an important plantation forestry tree in the country. All isolates were shown to be highly virulent. Results of the study consequently revealed that C. pirilliformis has a wider host range and geographic distribution in South Africa than previously recognized and that it is a potentially important pathogen of A. mearnsii.Tree Protection Co-operative Program (TPCP), the National Research Foundation (NRF; Grant Specific Unique Reference Number, 78566, 83924), the THRIP initiative of the Department of Trade and Industry (DTI), and the Department of Trade and Industry (DST)/NRF Centre of Excellence in Tree Health Biotechnology, South Africa.http://link.springer.com/journal/106582017-04-30hb2016Forestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant PathologyPlant Scienc

Ceratocystis wilt pathogens: History and biology-highlighting C. Cacaofunesta, the causal agent of wilt disease of cacao

Ceratocystis is a genus of ascomycete fungi that includes aggressive pathogens of economically important plants worldwide. This fungus is the causal agent of Ceratocystis wilt disease and canker disease, which often kills the plant causing major losses in agricultural production. In the last two decades, emerging diseases related to Ceratocystis infections have been greatly increased. Ceratocystis wilt of cacao is caused by C. cacaofunesta, one of the three well-established host-specific pathogens in the genus. Ceratocystis wilt of cacao has caused sporadic epidemics in the Americas, but its importance is often underestimated. Furthermore, the disease represents a serious threat to the world’s cacao production due to the risk of pathogen spread. Silvicultural practices in cacao agroforests, the marketing of seeds, and cacao grafting in association with a minimal knowledge of the biology of the pathogen effectively contributed to this threat. This chapter explores the controversial taxonomic and evolutionary history of the genus Ceratocystis as well as the biology of C. cacaofunesta. © Springer International Publishing Switzerland 2016