• The Plant Pathology Journal
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• 제37권2호
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• pp.137-151
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• 2021

The present study describes the bacterial blight of walnut, caused by Xanthomonas arboricola pv. juglandis (Xaj) in the northern Gyeongbuk province, Korea. Disease symptoms that appear very similar to anthracnose symptoms were observed in walnut trees in June 2016. Pathogens were isolated from disease infected leaves, fruits, shoots, bud, flower bud of walnut, and cultured onto yeast dextrose carbonate agar plates. Isolated bacteria with bacterial blight symptoms were characterized for their nutrient utilization profiles using Biolog GN2 and Vitek 2. In addition, isolates were subjected to physiological, biochemical, and morphological characterizations. Furthermore, isolates were identified using 16S rDNA sequence analysis, and multi-locus sequence analysis using atpD, dnaK, efp, and rpoD. To confirm pathogenicity, leaves, fruits, and stems of 3-year-old walnut plants were inoculated with bacterial pathogen suspensions as a foliar spray. One week after inoculation, the gray spots on leaves and yellow halos around the spots were developed. Fruits and stems showed browning symptoms. The pathogen Xaj was re-isolated from all symptomatic tissues to fulfill Koch's postulates, while symptoms were not appeared on control plants. On the other hand, the symptoms were very similar to the symptoms of anthracnose caused by Colletotrichum gloeosporioides. When walnut plants were inoculated with combined pathogens of Xaj and C. gloeosporioides, disease symptoms were greater in comparison with when inoculated alone. Xaj population size was more in the month of April than March due to their dormancy in March, and sensitive to antibiotics such as oxytetracycline and streptomycin, while resistant to copper sulfate.

• 한국미생물·생명공학회지
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• 제50권4호
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• pp.563-573
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• 2022

Xanthomonas arboricola pv. juglandis (Xaj) is a globally important bacterial pathogen of walnut trees that causes substantial economic losses in commercial walnut production. Although prophages are common in bacterial plant pathogens and play important roles in bacterial diversity and pathogenicity, there has been limited investigation into the distribution and function of prophages in Xaj. In this study, we identified and characterized 13 predicted prophages from the genomes of 12 Xaj isolates from around the globe. These prophages ranged in length from 11.8 kb to 51.9 kb, with between 11-75 genes and 57.82-64.15% GC content. The closest relatives of these prophages belong to the Myoviridae and Siphoviridae families of the Caudovirales order. The phylogenetic analysis allowed the classification of the prophages into five groups. The gene constitution of these predicted prophages was revealed via Roary analysis. Amongst 126 total protein groups, the most prevalent group was only present in nine prophages, and 22 protein groups were present in only one prophage (singletons). Also, bioinformatic analysis of the 13 identified prophages revealed the presence of 431 genes with an average length of 389.7 bp. Prokka annotation of these prophages identified 466 hypothetical proteins, 24 proteins with known function, and six tRNA genes. The proteins with known function mainly comprised prophage integrase IntA, replicative DNA helicase, tyrosine recombinase XerC, and IS3 family transposase. There was no detectable insertion site specificity for these prophages in the Xaj genomes. The identified Xaj prophage genes, particularly those of unknown function, merit future investigation.

• 한국산림과학회지
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• 제81권2호
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• pp.191-199
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• 1992

본(本) 실험(實驗)의 목적(目的)은 천원(天原), 영동(永東), 괴산(塊山)에서 재배(栽培)하고 있는 호두나무(Juglans sinensis Dode)에 가지마름과 고사(枯死)를 일으키는 병원균(病原菌)을 분리(分離)하여 동정(同定)하고 이들 병원균(病原菌)의 병원성(病原性) 및 배양적(培養的) 특성(特性), 발병율(發病率) 등(等)을 조사(調査)하는 것이었다. 분리(分離)된 병원균(病原菌)의 균학적(菌學的) 특성(特性)을 조사(調査)한 결과(結果), 이들균(菌)은 Botryosphaeria dothidea (Mou g. ex Fries) Casati et de Notaris(가지마름병(病)), Phomopsis albobestita Fairman (Phomopsis 가지마름병(病)), Melanconis juglandis (Ellis et Everhart) Graves(검은 돌기 가지마름병(病))로 동정(同定)되었다. 온실내(溫室內)에서 이들균(菌)의 병원성(病原性)을 검정(檢定)한 결과(結果) 2년생(年生) 호도나무 묘목(苗木)에서 병원성(病原性)이 입증(立證)되었다, 균사생육(菌絲生育)에 미치는 온도(溫度)의 영향(影響)을 조사(調査)한 결과(結果) B. dothidea와 P. albobestita는 $25{\sim}30^{\circ}C$ 사이에서 생육(生育)이 양호(良好) 하였으며, M. juglandis는 $20{\sim}25^{\circ}C$에서 생육(生育)이 가장 좋았으며 세 가지 균(菌)모두 $4^{\circ}C$와 $40^{\circ}C$에서는 생장(生長)하지 않았다. 분리(分離)된 세 균(菌)의 생육(生育)은 배지(培地)에 따라 차이(差異)를 보이지 않았으며 생육최적(生育最適) pH는 B. dothidea와 M. juglandis의 경우 4.0~8.0의 범위(範圍)이며 P. albobestita의 경우(境遇) 4.0~5.0으로 나타났다. 균사생육(菌絲生育)에 미치는 탄소원(炭素源)과 질소원(窒素源)의 영향(影響)을 조사(調査)한 결과(結果) B. dothidea의 경우(境遇) 탄소원(炭素源)으로는 glucose, sucrose, starch 및 maltose을, 질소원(窒素源)으로는 histidine과 potassium nitrate를 첨가(添加)한 배지(培地)에서 생육(生育)이 좋았다. P. albobestita의 경우(境遇) 탄소원(炭素源)으로 glucose 와 sucrose를 질소원(窒素源)으로 alanine과 potassium nitrate를 함유(含有)한 배지(培地)에서 생육(生育)이 좋았으며 M. juglandis는 glucose, sucrose, potassium nitrat, 함유(含有) 배지(培地)에서 생육(生育)이 좋았다. 주요 호도나무 재배지역(栽培地域)에서 발병(發病) 상황(狀況)을 조사(調査)한 결과(結果) 조사지역(調査地域) 모두에서 P. albobestita에 의한 피해(被害)가 가장 심하였으며, 15년생(年生) 이상(以上)된 수목(樹木)이 어린나무보다 더 피해(被害)가 큰 것으로 나타났다.