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Leaf blight and defoliation caused by two new pathovars of Xanthomonas axonopodis on Schinus terebinthifolius and Mabea fistulifera
Author(s) -
Ferraz H. G. M.,
Guimarães L. M. S.,
Badel J. L.,
Tótola M. R.,
Alfenas A. C.
Publication year - 2017
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.12705
Subject(s) - biology , pathovar , blight , inoculation , 16s ribosomal rna , phyllosphere , botany , leaf spot , multilocus sequence typing , xanthomonas , microbiology and biotechnology , pseudomonas , horticulture , bacteria , pseudomonadaceae , gene , genotype , biochemistry , genetics
Schinus terebinthifolius and Mabea fistulifera have been used for forest repositioning and urban forestry in Brazil. In October 2012, in a routine inspection at the research nursery of the Forestry Department of the Universidade Federal de Viçosa, in Minas Gerais, Brazil, a mortality of approximately 40% of the seedlings was observed as a result of diseases characterized by leaf blight and intense defoliation, which culminated in the death of the plants. Microscopy observations revealed oozing from the infected tissue and isolations revealed a bacterial aetiology for both diseases. Bacterial cells that formed bright yellow mucoid colonies with round edges were routinely isolated from lesion margins. Inoculation of isolated strains into healthy seedlings reproduced the symptoms observed under natural conditions. Bacterial cells showing the same morphological, biochemical and molecular characteristics as those originally isolated from naturally infected plants were reisolated from inoculated plants. Morphological, physiological and biochemical tests as well as 16S rDNA sequencing and multilocus sequence analysis using four housekeeping genes, dnaK , fyuA , gyrB and rpoD , confirmed the newly isolated strains belong to Xanthomonas axonopodis . Plant cross‐inoculations showed the strains did not belong to any known phylogenetically related pathovar. Pathovars X. axonopodis pv. schini pv. nov. and X. axonopodis pv. mabeae pv. nov. are proposed as the causal agents of bacterial leaf blight on S. terebinthifolius and M. fistulifera , respectively.