Pucciniales on Annona (Annonaceae) with special focus on the genus Phakopsora

Abstract

The known species of Pucciniales on the tree genus Annona (Annonaceae), Phakopsora cherimoliae, Batistopsora crucis-filii, B. pistila, as well as the anamorphic species of Aecidium annonae and Uredo rolliniae, were investigated by light microscopy and DNA sequencing. For DNA extraction, N-Phenacylthiazolium bromide (PTB) was used to achieve a higher yield of DNA from herbarium specimens. The phylogenetic analyses were based on the ITS1–5.8S–ITS2 region, partial LSU and SSU of the nuclear rDNA, and the mitochondrial cytochrome oxidase subunit 3. The molecular as well as the morphologic investigations indicated that the genus Batistopsora is synonymous with Phakopsora. The two Batistopsora species appeared in all phylogenies within Phakopsora. They form a monophyletic clade together with P. cherimoliae as well as with the anamorphic Uredo rolliniae and the herein newly described species Phakopsora annonae-sylvaticae. Therefore, the following new combinations have been made: Phakopsora crucis-filii, P. pistila and P. rolliniae. Phakopsora crucis-filii and P. pistila could not be distinguished by the used sequences but are morphologically and ecologically well separated. This contradiction is discussed. Phakopsora crucis-filii is firstly reported as a pathogen on the fruit tree Annona squamosa. The species show host preferences to species groups of Annona at the sub-generic level and distribution patterns similar to those of their hosts. In comparison with the rust fungal genus Dasyspora, which occurs on Xylopia (Annonaceae) also in the Neotropics, the Phakopsora spp. on Annona show similar phylogeographical patterns. The redetermination of the host plants has shown that A. annonae does not occur on Annonaceae but on Diospyros hispida (Ebenaceae). Therefore, the new species, Aecidium verannonae, has to be described for the Aecidium species, which occurs really on Annona. It did not appear to be closely related to the Phakopsoraceae in the phylogenetic analysis. An identification key for all known rust fungi on Annona is given.