Molecular analysis ofPhytophthoradiversity in nursery‐grown ornamental and fruit plants

• DOI: 10.1111/ppa.12362
• Publication Date: 2015-02-24T07:39:55Z
• Authors: M. I. Prigigallo; S. Mosca; S. O. Cacciola; D. E. L. Cooke; L. Schena
• Keywords: 0301 basic medicine; 03 medical and health sciences; nurseries; Phytophthora spp.; genus-specific primers; potted plants; 15. Life on land; genus-specific primers; metabarcoding analyses; nurseries; Phytophthora spp.; potted plants; metabarcoding analyses

The genetic diversity ofPhytophthoraspp. was investigated in potted ornamental and fruit tree species. A metabarcoding approach was used, based on a semi‐nestedPCRwithPhytophthoragenus‐specific primers targeting theITS1 region of therDNA. More than 50ITS1 sequence types representing at least 15 distinctPhytophthorataxa were detected. Nine hadITSsequences that grouped them in defined taxonomic groups (P. nicotianae,P. citrophthora,P. meadii,P. taxonPgchlamydo,P. cinnamomi,P. parvispora,P. cambivora,P. niederhauseriiandP. lateralis) whereas three phylotypes were associated to two or more taxa (P. citricolataxon E orIII;P. pseudosyringae,P. ilicisorP. nemorosa; andP. cryptogea,P. erythroseptica,P. himalayensisorP. sp. ‘kelmania’) that can be challenging to resolve withITS1 sequences alone. Three additional phylotypes were considered as representatives of novelPhytophthorataxa and defined asP. meadii‐like,P. cinnamomi‐like andP. niederhauserii‐like. Furthermore, the analyses highlighted a very complex assemblage ofPhytophthorataxa in ornamental nurseries within a limited geographic area and provided some indications of structure amongst populations ofP. nicotianae(the most prevalent taxon) and other taxa. Data revealed new host–pathogen combinations, evidence of new species previously unreported in Italy (P. lateralis) or Europe (P. meadii) and phylotypes representative of species that remain to be taxonomically defined. Furthermore, the results reinforced the primary role of plant nurseries in favouring the introduction, dissemination and evolution ofPhytophthoraspecies.