• Research in Plant Disease
• /
• v.9 no.2
• /
• pp.57-63
• /
• 2003

Clubroot disease of curcifer crops caused by Plasmodiophora brassicae had been first reported in 1928 in Korea, and maintained mild occurrence until 1980s. Since 1990s the disease has become severe in alpine areas of Kyonggi and Kangwon, gradually spread to plain fields throughout the country, and remains as the great-est limiting factor for its production. Researches on the disease has begun in late 1990s after experiencing severe epidemics. Survey of occurrence and etiological studies have been carried out, particularly, on the pathogen physiology, race identification, quantification of soil pathogen population, and host spectrum of the pathogen. Ecology of gall formation and its decay, yield loss assessment associated with time of infection, and relationships between crop rotation and the disease incidence was also studied during late 1990s. In studies of its control, more than 200 crucifer cultivars were evaluated for their resistance to the disease. Lime applica-tion to field soil was also attempted to reduce the disease incidence. Resistant radish and welsh onion were recommended as rotation crops with crucifers after 3-year field experiments. However, so for, most studies on clubroot disease in Korea have been focused on chemical control. Two fungicides, fluazinam and flusulfamide, were selected and extensively studied on their application technologies and combination effects with lime application or other soil treatment. To develop environmentally-friendly control methods, solar-disinfection of soil, phosphoric acid as a nontoxic compound, and root-parasiting endophytes as biocontrol agents were examined for their effects on the disease in fields. In the future, more researches are needed to be done on development of resistant varieties effective to several races of the pathogen, establishment of economically-sound crop rotation system, and improvement of soil-disinfection technique applicable to Korean field condi-tion, and development of methodology of pretreatment of fungicides onto seeds and seedbeds.

• The Plant Pathology Journal
• /
• v.21 no.4
• /
• pp.369-376
• /
• 2005

Turnip mosaic virus (TuMV) is an infectious viral pathogen on the cruciferous crops, predominantly Chinese cabbage (Brassica campestris subsp. pekinensis) and radish (Raphanus sativus). On the basis of the symptom development in selective differential hosts from indicator host species, Chinese cabbage and Korean radish inbred lines, the representative eight isolates of TuMV were divided into two major groups/or six types. Group I includes Th 1, Ca-ad7, and Cj-ca2-1 isolates, while group II includes the other isolates (rg-pfl, r 9-10, Rhcql-2, Stock and Mustard). According to the molecular phylogenetic analysis, these isolates, however, divided into two groups and two independent isolates. Phylogenetic analysis indicated that four isolates (Tu 1, r9-10, Stock and Rh-cql-2) formed a distinct phylogenetic group, and the other two isolates (Ca-ad7 and Cj-ca2-1) also formed another group. Mustard and rg-pfl isolates did not seem to have any relationship with these two groups. Taken together, these results indicated that virulence differentiation on host plants, molecular phylogenetic analysis of the nucleotide and the deduced amino acid of TuMV coat proteins did not show any relationship. The multi-resistant lines, Wonyae 20026 and BP058 in Chinese cabbage represent valuable genetic materials that can be used for crucifer breeding programs on TuMV resistance, but not in Korean radish.

• Research in Plant Disease
• /
• v.29 no.2
• /
• pp.158-167
• /
• 2023

Black rot of Chinese cabbage caused by Xanthomonas campestris pv. campestris (Xcc) is one of the most severe diseases in crop cultivation. To define the resistance characteristics of Chinese cabbage to Xcc, we tested the virulence of eight Xcc isolates in four susceptible cultivars of Chinese cabbage. The isolates of Xcc showed different the virulence on the cultivars. On the other hand, we selected 22 resistant or moderately resistant cultivars of Chinese cabbage to Xcc and tested the occurrence of black rot on the cultivars caused by the isolates of Xcc. Mean disease severity of black rot on the Chinese cabbage caused by each isolate was also positively correlated with the virulence of Xcc isolates. Furthermore, the development of black rot in each cultivar increased according to virulence of Xcc isolates. The number of resistant cultivars of Chinese cabbage to eight isolates of Xcc decreased according to the virulence increase of bacteria. Taken together, these results suggest that resistance of Chinese cabbage cultivars to Xcc is likely affected by the virulence of Xcc isolates, but not result from race differentiation.

• Research in Plant Disease
• /
• v.19 no.2
• /
• pp.95-101
• /
• 2013

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is one of the most serious diseases of crucifers world-wide. To establish the efficient screening method for resistant cabbage to Xcc, different inoculation methods, inoculation positions, growth stages of seedlings, and incubation temperatures after inoculation were investigated with the seven cabbage cultivars showing different resistance degrees to the pathogen. Clipping with mouse-tooth forceps was better inoculation method than piercing with 18 pins or cutting with scissors to distinguish the level of resistance and susceptibility. In inoculation using mouth-tooth forceps, clipping the edges of the leaves near veins is more effective than injuring the veins of the leaves directly. In addition, the inoculated plants kept at $22^{\circ}C$ showed more clear resistant and susceptible responses than those kept at 26 or $30^{\circ}C$. On the basis of the results, we suggest that an efficient screening method for resistance of cabbage cultivars to black rot is to clip the edges of the leaves near veins of the four-week-old seedlings with mouth-tooth forceps dipped in a suspension of Xcc at a concentration of $7{\times}10^7$ cfu/ml and incubate the inoculated plants in a growth room at $22^{\circ}C$ with 12-hr light a day.

• Applied Biological Chemistry
• /
• v.16 no.3
• /
• pp.146-165
• /
• 1973

Crop damages caused by sulfur dioxide poisoning were studied with respect to physiology of lesion, yield loss and prevention measures. The results are summarized as follows; 1. On the physiology of injury: The sulfur dioxide gas did no: affect the pH and $E_h$ values of the tested leaf juice of plants. Peroxidase activity was inhibited just after sulfur dioxide treatment but gradually recovered to normal after 10 hours. Methanolic chlorophyll solution was instantaneously and irreversibly bleached by the addition of sulfur dioxide gas with no evidence of pheophytin formation. It seems that chlorophyll forms colourless addition product or is reduced to colourless form with either sulfur dioxide gas or sulfurous acid. Chlorophyll in the chloroplast was also bleached by the sulfur dioxide treatment, as in the case of methanolic solution of chlorophyll, except that the rate of bleaching was rather slow, requiring 1-2 hours. It appears that the most inflicting cause of sulfur dioxide gas to plants may be the destruction of chlorophyll by the poisoning gas. 2. On the effects to crop yield: The crop yield losses were proportional to the concentration of inflicting sulfur dioxide gas. The order of tolerence of the crops to the sulfur dioxide gas was as follows - chinese cabbage being the most susceptible; wheat, paddy rice, barley, soybean, welsh onion, radish and chinese cabbage. The crucifer crops were generally found more susceptible than other crops studied. With respect to the growing stages of crops exposed to sulfur dioxide gas, it was found that the flowering stage was the most susceptible fellowed by panicle forming, milky and tillering in the decreasing order of susceptibility. 3. On the preventive measures of yield losses: Soil applications of potassium, wollastonite, lime or spray of lime water were effective to prevent yield losses from sulfur dioxide fumigation of paddy rice, barley, and soybeans. The most responsive treatment was lime water spray for all crops tested. In case of sulfur dioxide fumigated paddy rice, the lime water spray also increased carbon assimilation.

• Horticultural Science & Technology
• /
• v.29 no.6
• /
• pp.633-640
• /
• 2011

Brassica rapa is an A genome model species for Brassica crop genetics, genomics, and breeding. With the completion of sequencing the B. rapa genome, functional analysis of the genome is forthcoming issue. The expressed sequence tags are fundamental resources supporting annotation and functional analysis of the genome including identification of tissue-specific genes and promoters. As of July 2011, 147,217 ESTs from 39 cDNA libraries of B. rapa are reported in the public database. However, little information can be retrieved from the sequences due to lack of organized databases. To leverage the sequence information and to maximize the use of publicly-available EST collections, the Brassica rapa tissue-specific EST database (BrTED) is developed. BrTED includes sequence information of 23,962 unigenes assembled by StackPack program. The unigene set is used as a query unit for various analyses such as BLAST against TAIR gene model, functional annotation using MIPS and UniProt, gene ontology analysis, and prediction of tissue-specific unigene sets based on statistics test. The database is composed of two main units, EST sequence processing and information retrieving unit and tissue-specific expression profile analysis unit. Information and data in both units are tightly inter-connected to each other using a web based browsing system. RT-PCR evaluation of 29 selected unigene sets successfully amplified amplicons from the target tissues of B. rapa. BrTED provided here allows the user to identify and analyze the expression of genes of interest and aid efforts to interpret the B. rapa genome through functional genomics. In addition, it can be used as a public resource in providing reference information to study the genus Brassica and other closely related crop crucifer plants.

• Research in Plant Disease
• /
• v.20 no.4
• /
• pp.235-244
• /
• 2014

Clubroot and Fusarium wilt of cole crops (Brassica oleracea L.) are destructive diseases which for many years has brought a decline in quality and large losses in yields all over the world. The breeding of resistant cultivars is an effective approach to reduce the use of chemical fungicides and minimize crop losses. This study was conducted to evaluate the resistance of 60 cabbage (B. oleracea var. capitata) and 6 broccoli (B. oleracea var. italica) lines provided by The RDA-Genebank Information Center to clubroot and Fusarium wilt. To investigate resistance to clubroot, seedlings of the genetic resources were inoculated with Plasmodiophora brassicae by drenching the roots with a mixed spore suspension (1 : 1) of two isolates. Of the tested genetic resources, four cabbage lines were moderately resistant and 'K166220' represented the highest resistance to P. brassicae. The others were susceptible to clubroot. On the other hand, to select resistant plants to Fusarium wilt, the genetic resources were inoculated with Fusarium oxysporum f. sp. conglutinans by dipping the roots in spore suspension of the fungus. Among them, 17 cabbage and 5 broccoli lines were resistant, 16 cabbage lines were moderately resistant, and the others were susceptible to Fusarium wilt. Especially, three cabbage ('IT227115', 'K161791', 'K173350') and two broccoli ('IT227100', 'IT227099') lines were highly resistant to the fungus. We suggest that the resistant genetic resources can be used as a basic material for resistant B. oleracea breeding system against clubroot and Fusarium wilt.