Identification, Virulence, and Distribution of Two Biovars ofPseudomonas syringaepv.actinidiaein New Zealand

Abstract

Pseudomonas syringae pv. actinidiae, the causal agent of bacterial canker of kiwifruit, was detected for the first time in New Zealand in November 2010. Only in Bay of Plenty, one of the four regions where this pathogen had been detected, did symptoms evolve beyond leaf spots, resulting in cane die-back, wilting of canes, and canker, sometimes leading to death of the vine. Molecular analysis (cts haplotype and BOX-polymerase chain reaction [PCR] electrophoretic pattern) of strains isolated from different regions of New Zealand revealed that two biovars could be distinguished. They have been called biovar 3 and biovar 4 to differentiate them from strains from Japan (biovar 1) or Korea (biovar 2), which have a different cts haplotype or a different BOX-PCR pattern. Biovars 3 and 4 displayed different degrees of virulence, as measured by their ability to cause leaf spots on young, potted kiwifruit plants. Biovar 3, which has also been present in Italy since 2008 and in France, was found in the Bay of Plenty, where cane diebacks were observed. In contrast, no symptoms other than leaf spots have been observed in orchards where strains of biovar 4 have been isolated. We report the distribution and the disease progression of biovars 3 and 4 in New Zealand.

Origin of the Outbreak in France of Pseudomonas syringae pv. actinidiae Biovar 3, the Causal Agent of Bacterial Canker of Kiwifruit, Revealed by a Multilocus Variable-Number Tandem-Repeat Analysis

“…actinidiae, the causal agent of bacterial canker of kiwifruit (Actinidia spp. ), is considered to be a pandemic pathogen and has been isolated around the world over the last 30 years (17,18). Vanneste et al (18) suggested classifying these strains into three biovars, biovar 1, biovar 2, and biovar 3, according to phenotypic, pathogenic, and genomic features.…”

“…actinidiae biovar 3 was reported first in China (22) and more recently in Italy in 2008 (23,24). It was then observed elsewhere in Europe (France and Portugal, 2010; Turkey, Switzerland, and Spain, 2011; Germany and Slovenia, 2013, and Greece, 2014 [18,[25][26][27]) and outside Europe, in New Zealand and Chile (18). Pseudomonas syringae pv.…”

“…actinidifoliorum caused only necrotic symptoms on leaves (28); strains of this pathovar were previously described as P. syringae pv. actinidiae biovar 4 (18). P. syringae pv.…”

“…P. syringae pv. actinidifoliorum was isolated in New Zealand (18), in Australia (29), and in France in 2011 (28). Two lineages of P. syringae pv.…”

Characterization of biovar 3 strains of <i>Pseudomonas syringae</i> pv. <i>actinidiae</i> isolated in Japan.

“…（Chapman Cunty et al, 2014;Ferrante and Scortichini, 2015;澤田ら，2014a，2014b;Vanneste, personal communication;Vanneste et al, 2013 Chapman et al, 2012;Cunty et al, 2014;Ferrante and Scortichini, 2015;Han et al, 2003;McCann et al, 2013;三好ら， 2012;澤 田 ら，2014a;Takikawa et al, 1989;Vanneste et al, …”