Abstract
Phyllactinia cassiae-fistulae and its Ovulariopsis anamorph, a causal agent of powdery mildew on Cassia fistula, have been found in Thailand for the first time. Phylogenetic analysis using the 28S ribosomal DNA sequences clearly demonstrated that P. cassiae-fistulae distinctly formed a unique clade at the basal part ofPhyllactinia with 100% bootstrap support. This phylogenetic analysis supports the unique morphology of P. cassiae-fistulae anamorph having cylindrical-ellipsoil conidia and short conidiophores similar to Oidium species. Key words: Morphology, phylogeny, powdery mildew, Cassia fistula, Senna siamea.
Highlights
During the survey of powdery mildews from 2008 to 2011 in Northern Thailand, several interesting powdery mildews were discovered
The 28S ribosomal DNA (rDNA) sequences consisted of two sequences from C. fistula and one sequence from S. siamea were aligned with 24 sequences of Leveillula, Phyllactinia and Pleochaeta retrieved from DNA database (Takamatsu et al, 2008)
The morphological observations of anamorph of P. cassiaefistulae demonstrated that the cylindrical-ellipsoid conidia are quite distinct from other known Phyllactinia species having lanceolate conidia (Braun, 1987; Paul and Thakur, 2006; Braun and Paul, 2009)
Summary
During the survey of powdery mildews from 2008 to 2011 in Northern Thailand, several interesting powdery mildews were discovered. One of them has been found on Cassia fistula and Senna siamea (Caesalpinioideae; Fabaceae) and was identified as Phyllactinia cassiaefistulae. This species was first described by Paul and Thakur (2006) in India as a new variety, P. bauhiniae var. Kirschner and Chen (2008) demonstrated first record of this species on C. fistula in Taiwan (without teleomorphic stage) and reported detailed morphological characteristics of anamorphic stage. Morphological observations showed conidiophore shorter than other Ovulariopsis species anamorph of Phyllactinia and showed production of cylindrical-ellipsoid conidia. This study is the first report of P. cassiae-fistulae from Thailand, and the first report of this species on S. siamea in the world
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