Bacterial phytopathogen Pectobacterium causes soft rot disease in several vegetable crops globally, resulting in heavy agricultural losses at both the pre and postharvest stages. The present work was carried out to screen Kimchi cabbage genetic resources conserved at the National Agrobiodiversity Center, Rural Development Administration, Korea, for resistance against the soft rot pathogen Pectobacterium carotovorum subsp. carotovorum KACC 21701 over a period of three years (from 2020 to 2022). Infection of the phytopathogen was carried out at four-leaf stage and for each accession, twenty-five plants per germplasm were infected with KACC 21701. Kimchi cabbage cultivars Wangmatbaechu, Seoulbaechu, and CR Kiyoshi were used as control. Seven-days post-infection, the Disease Index (DI) values were manually recorded from zero to four, zero matched perfectly heathy plants and four completely dead plants. The 682 accessions of Kimchi cabbage exhibited varying degrees of disease resistance to KACC 21701 and thirty accessions, exhibiting a DI≤2, were considered for replication studies. During the replication studies, four landrace germplasms (IT102883, IT120036, IT120044, and IT120048) and one cultivar (IT187919) were confirmed to be moderately susceptible to KACC 21701. Results of the preliminary screening as well as replication studies were documented for the all the 682 germplasms. Addition of such information to the passport data of stored germplasms might serve as potential bio-resource for future breeders and researchers to develop resistant varieties or study the mechanisms involved in resistance of plants to such phytopathogen.

Calla lily is a mainstream floricultural crop but itscommercial success is limited by severe susceptibility to softrot. This disease can be controlled to some extent by imple-menting appropriate cultural practices but developing resis-tant cultivars against this pathogen is the most promisinglong-term strategy. The purpose of this work was to developnew cultivars resistant to this bacterial disease by initiatingan appropriate breeding programme. Field observations of120 resistant lines selected by a leaf-disk susceptibility testwere carried out and survival rates were measured. Twolines were selected after further evaluation of resistancelevel, flowering characteristics and following guidelines forconduct of tests for distinctness, homogeneity, and stability.Further preference testing of the selected lines by growers,consumers, researchers and agricultural advisors was car-ried out with excellent results. The selected new lines are‘Silky White’ and ‘Mont Blanc’ which emerge as the first,soft-rot resistant calla lily cultivars from our breeding program.

Mushroom is cultivated in many areas of the Korea as one of the major economical crops. The production areas have steadily increased approximately 3,674 ha in 2002 to 4,118 ha in 2005. Several bacteria have been known as the causal agents of certain diseases of cultivated button mushroom, Agaricus bisporus, and oyster mushroom, Pleurotus ostreatus. It is well known as bacterial diseases of the cultivated mushroom such asbrown blotch, mummy disease, bacterial pit, bacterial rot and weeping disease, ginger blotch, and drippy gill. Unknown soft rot bacterium was isolated from sunken browning symptom of cultivated oyster mushrooms grown in Korea. The symptoms are appear as a sunken browning lesions on the caps of affected mushrooms. The bacterium causes a rapid soft rot of cultivated mushrooms in comparison with brown blotch bacteria at temperatures above 25℃. From these lesions we isolated one bacterial strain (designated OM1). Inoculation of bacterial isolates into mushroom caps yielded characteristic sunken brown, watersoaked and severe soft rot symptoms, but which were indistinguishable in early stage from those of the bacterial brown blotch well known to mushroom growers. Results of Gram stain and biochemical tests identified this isolate as Burkholderia gladioli pv. agaricicola. This was confirmed by pathogenicity, physiological and biochemical characteristics, and results of an analysis of the 16S rRNA gene sequences and the fatty acids profile. This is the first report of the isolation of B. gladioli pv. agaricicola from cultivated oyster mushroom in Korea.

Erwinia rarotovora subsp carotovora에 의한 콩나물 무름병 발생을 인위적인 조건하에서 조사하였다. 콩나물의 재배 온도가 콩나물 무름병 발생과 생장에 미치는 영향은 30℃이상의 고온에서 무름병 발생율이 높아졌으며 35℃에서는 약 22%의 발병율을 나타내었다. 종피와 자엽 부위에 인위적인 상처를 낸 경우 70%이상의 발병율을 보였으며 콩나물의 신장을 억제하였다. 습도는 90%이상 유지시 33%의 발병율을 보였으며 콩나물의 생장을 억제시켰다. 콩나물 재배 배출액을 관수액으로 재이용하였을 때 무름병의 발병율이 증가하였다.

감자 괴경에 타박상을 입혔거나 세균현탁액을 주입했을 때 낮은 water potential(-6.46 bar) 보다 높은 water potential (-6.06 bar)에서 더 쉽게 부패를 초래하였으며, 높은 water potential을 가진 괴경과 낮은 water potential을 가진 괴경 사이에 있어서의 부패의 진전에는 큰 차이를 발견할 수 있었으며, 현탁액의 농도의 종류에 따른 괴경의 연부병의 이병정도는 높은 water potential에서 높았으며, 세균 현탁액 농도의 은 높은 water potential에서 이며 낮은 water potential에 서는 이었으며, 높은 water potential과 낮은 water potential 에서는 작은 차이를 인정할 수 있었다. 이 시험에서 감자는 상처나 타박상이 나지 않도록 다루어야 하며 수확후 충분히 건조하여야 오랜 운반과 저장중에 연부병 발생을 크게 줄일 수 있다는 것을 나타낸다.

We performed field trials to assess levels of changes in intrinsic properties and resistance against soft rot of the potato cultivar ‘Irish Cobbler’ upon the introduction of the Shiva-1 gene. Each five lines, transformed with Shiva-1 gene controlled by the PAL5 promoter (P) and by the CaMV 35S promoter (E) were evaluated in the field. In based on evaluation of 10 defined morphological characteristics, all the transgenic clones of both lines proved to be true to type. When five agronomic characteristics were taken into account as well, all the transgenic lines except E8 were considered to be true to type. According to the result of northern blot analysis, seven (P1, P3, P4, P6, E10, E12, and E16) transgenic clones could be distinguished clearly from corresponding untransformed clones. But in three lines (P8, E5, and E8), no hybridization signal was detected. There seems to be positive correlation between the levels of resistance to soft rot and the transgenic expression at mRNA levels in P lines. But in the case of E lines, however, there doesn’t seem to be any correlation between the levels of disease resistance and mRNA expression