Outbreak and Spread of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae Biovar 3 in Korea

Abstract

A bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), is a causal agent of kiwifruit bacterial canker worldwide. Psa biovar 3 (Psa3) was first detected in 2011 at an orchard in Dodeok-myeon, Goheunggun, Jeonnam Province in Korea. In this study, we present the results of an epidemiological study regarding Psa3 occurrence on kiwifruit orchards in Korea for the period of 2013 to 2015. Since the first detection of Psa3 in 2011, there was no further case reported by 2013. However, Psa3 was rapidly spreading to 33 orchards in 2014; except for three orchards in Sacheonsi, Gyeongnam Province, most cases were reported in Jeju Island. Entering 2015, bacterial canker by Psa3 became a pandemic in Korea, spreading to 72 orchards in Jeju Island, Jeonnam, and Gyeongnam Provinces. Our epidemiological study indicated that the first Psa3 incidence in 2011 might result from an introduction of Psa3 through imported seedlings from China in 2006. Apart from this, it was estimated that most Psa3 outbreaks from 2014 to 2015 were caused by pollens imported from New Zealand and China for artificial pollination. Most kiwifruit cultivars growing in Korea were infected with Psa3; yellow-fleshed cultivars (Yellow-king, Hort16A, Enza-gold, Zecy-gold, and Haegeum), red-fleshed cultivars (Hongyang and Enza-Red), green-fleshed cultivars (Hayward and Daeheung), and even a kiwiberry (Skinny-green). However, susceptibility to canker differed among cultivars; yellow- and red-fleshed cultivars showed much more severe symptoms compared to the green-fleshed cultivars of kiwifruit and a kiwiberry.

The application of the CRISPR–Cas9 system in Pseudomonas syringae pv. actinidiae

“…80% of our authors rate our submission process as 'excellent' or 'very good'. 5. Your article will be published on an interactive journal platform with advanced metrics.…”

“…Strains of Psa3 (also known as Psa biovar3) do not produce any known toxins. Psa3 strains have been detected in China [4] and are responsible for the current worldwide pandemic of bacterial canker in kiwifruit with reports from Europe, New Zealand, Chile, Korea and Japan [5,6].…”

Adaptation of the New Zealand Psa risk model for forecasting kiwifruit bacterial canker in Korea

“…Kiwifruit bacterial canker is the most severe threat to Korean kiwifruit growers. Although the disease was first reported on cultivar Hayward in 1988 (Koh et al ., ), it has caused more severe damage to the cultivars of yellow‐ and red‐fleshed kiwifruits such as imported Hort16A, Yellow King and Hongyang cultivars and domestically bred cultivars in major kiwifruit‐growing areas in Korea (Kim et al ., ). Recently, some kiwifruit orchards had to shut down due to severe, incurable disease outbreaks, and others are suffering from persistent occurrences of the disease every year.…”

Incidence Rates of Major Diseases of Kiwiberry in 2015 and 2016

“…Hayward was introduced to Korea in the late 1970s and Hort16A was introduced to Jeju Island, Korea, in 2004. Since then, many domestically bred cultivars of yellow-fleshed kiwifruit such as Haegeum, Zecy-gold and Halla-gold, as well as other imported yellow- and red-fleshed cultivars have been grown in Korea, and their cultivation area has recently been expanding rapidly due to a strong market demand for kiwifruits ( Kim et al, 2016b ). Kiwiberry is native to the Korean peninsula and has been commonly found in mountainous regions for thousands of years.…”

“…Psa3 is responsible for the world-wide outbreaks of bacterial canker on fuzzy kiwifruits, especially on yellow- and red-fleshed cultivars ( Butler et al, 2013 ; Chapman et al, 2012 ; McCann et al, 2013 ; Vanneste, 2012 ). Pollen contaminated with Psa3 turned out to be one of the causal inoculum for recent epidemics of bacterial canker on various cultivars of the fuzzy kiwifruits in Korea ( Kim et al, 2016a , 2016b ). Since the same kind of Psa3 was isolated from the diseased Skinny-green tree and extra pollen kept in a freezer at the farmer’s orchard without epidemic history of bacterial canker, it was assumed that pollen contaminated with Psa3, which was imported from China and used for pollination in 2014, might have been responsible for the bacterial canker on the Skinny-green tree.…”