Intersterility, morphology and taxonomy of Ceratocystis fimbriata on sweet potato, cacao and sycamore

Abstract

Ceratocystis fimbriata is a large, diverse complex of species that cause wilt-type diseases of many economically important plants. Previous studies have shown that isolates in three monophyletic lineages within the Latin American clade of C. fimbriata are host-specialized to cacao (Theobroma cacao), sweet potato (Ipomoea batatas) and sycamore (Platanus spp.), respectively. We paired testers of opposite mating type from isolates of these lineages to find intersterility groups. Two intersterility groups corresponded to the sweet potato and sycamore lineages, respectively. The cacao lineage contained two intersterility groups, corresponding to two genetic sublineages centered in western Ecuador and Brazil/Costa Rica/Colombia. Six isolates from cacao that were not members of the cacao lineage and were not pathogenic to cacao in an earlier study also were intersterile with members of the two cacao intersterility groups. Some pairings between testers from different lineages or sublineages yielded perithecia from which a few abnormal progeny could be recovered, typical of interspecific hybrids. These progeny showed abnormal segregation of the MAT-2 gene and mycelial morphology, showing that they were indeed the result of crosses. Isolates of the sweet potato, cacao, and sycamore lineages were indistinguishable morphologically except for the presence or absence of a doliform (barrel-shaped) conidial state and minor differences in size of perithecial bases and necks and ascospores. C. fimbriata originally was described from sweet potato. We describe the cacao pathogen as a new species, Ceratocystis cacaofunesta and we raise the sycamore pathogen from a form to species Ceratocystis platani.

Clonal structure of Ceratocystis manginecans populations from mango wilt disease in Oman and Pakistan

“…The fungus has been found on Acacia mangium in Indonesia (Tarigan et al 2011), a country where mango is also widely planted. Alternatively C. manginecans could originate from South America, which appears to be an area of substantial genetic variation for C. fimbriata s.l., including the many cryptic species encompassed by this group (Barnes et al 2001;Baker et al 2003;Engelbrecht and Harrington 2005;Rodas et al 2008;Van Wyk et al 2009;Van Wyk et al 2010;). …”

“…from Eucalyptus (Barnes et al 2003); C. cacaofunsta Engelbrecht and Harrington from Theobroma cacao and C. platani Engelbrecht and Harrington from Platanus sp. (Engelbrecht and Harrington 2005).…”

A possible centre of diversity in South East Asia for the tree pathogen, Ceratocystis manginecans

“…The species resides in Ceratocystis sensu stricto (De Beer et al, 2014) that includes numerous cryptic species, the majority of which are aggressive tree pathogens (Al Adawi et al, 2013b;Engelbrecht and Harrington, 2005;Ocasio-Morales et al, 2007;Roux and Wingfield, 2013;Wingfield et al, 2013). C. manginecans has also been reported as a serious pathogen of Acacia mangium trees in Indonesia, identified at the time as the new species C. acaciivora (Tarigan et al, 2011).…”

Comparison of procedures to evaluate the pathogenicity of Ceratocystisfimbriata sensu lato isolates from Eucalyptus in South Africa

“…Some species threaten the productivity of fruit tree crops such as coffee (Coffea spp.) (Marin et al 2003), cacao (Theobroma cacao) (Engelbrecht and Harrington 2005) and mangoes (Mangifera indica) (Al Adawi et al 2006, van Wyk et al 2007, while others are important pathogens of species used to establish commercial forest plantations such as Eucalyptus (Roux et al 2000).…”