• Research in Plant Disease
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• v.11 no.2
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• pp.106-114
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• 2005

To breed powdery mildew resistant varieties, 104 accessions of Cucurbita spp. germplasm were evaluated. Powdery mildew resistance and horticultural characteristics of the accessions were investigated in the field conditions. C. martinezii was selected for high resistance to powdery mildew in the field. The growth of powdery mildew pathogen and response of leaf surface tissue to the pathogen were observed after artificial inoculation to resistant C martinezii and susceptible C. moschata cv. 'Wonye No.402'. Mycelium growth was very clearly different between resistant C. martinezii and susceptible C moschata cv. 'Wonye No. 402' at 5 days after inoculation at the adult stage. Interspecific hybridization was attempted to transfer powdery mildew resistance gene(s) from C. martinezii to C. moschata. A single dominant gene action was postulated as deter mining powdery mildew resistance at the seedling stage. But for the effective selection of powdery mildew resistant individuals, it was established that adult plant resistance should be confirmed in the field conditions after the seedling test. Through the seedling and field tests, C. moschata lines resistant to powdery mildew and superior to horticultural characteristics, were selected after 2 backcrossing and 3 selfing generations. The fruit characteristics of newly developed lines were similar to those of the recurrent parent, 'Jaechenjarae'.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.496-501
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• 2009

In order to promote the efficiency of strawberry breeding programs, pollen viability of strawberry, 'Seolhyang' was investigated using the fluorochromatic reaction test and seed set under controlled environment. Pistil receptivity was also assessed by hand pollination. Four varieties including 'Maehyang' were used for the test of pistil receptivity with 'Seolhyang' as a pollen parent. Pollen viability remained high for several days under dry conditions as below 33% relative humidity while the greatest loss of viability occurred at 76% relative humidity. The viability was rapidly decreased at high humidity and almost all grains were unviable in 7 days after storage. Pollen viability does not appear to be drastically reduced if the relative humidity is low. Therefore, humidity is more important factor than temperature for the pollen viability in Fragaria${\times}$ananassa. The rate of seed set by hand pollination lasted higher than the average of 77.2% from 2 to 8 days after emasculation when the daily average temperature was around $15^{\circ}C$ in plastic house. It began to decline gradually from 10 days and had decreased dramatically after 12 days except several cultivars. Based on the daily mean accumulated temperature, it is recommended to have an artificial pollination between the range of $45{\sim}140^{\circ}C$ after the emasculation to increase the rate of seed set in strawberry.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.318-323
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• 2008

Nokwon, a new cultivar for vegetable soybean, was developed from the cross between Keunolkong and Hyangnam-1 and released in 2006. The pedigree of Nokwon, designated as Milyang 153 in 2003, was SS96425-2B-11-4-1-1-1. Nokwon, used as a vegetable soybean was characterized by dark green pod, large seed, very short plant height, and lodging resistance. Nokwon has determinate growth habit, white flowers, gray pubescence, oval leaf shape and brown pods at maturity. The mature seeds have a greenish yellow seed coat with brown hilum and yellow cotyledon. In Korea, Regional Yield Trials (RYT) for vegetable soybean from 2004 to 2006, Nokwon shows strong tolerance to soybean mosaic virus and lodging in fields. Fresh pods of Nokwon harvested at the beginning of August, and stem height was 11cm shorter than 45 cm of Hwaeomputkong. In the same tests, fresh pod of Nokwon (11.4 ton/ha) yielded 14% higher than Hwaeomputkong (10.0 ton/ha). Nokwon had 5.9 cm fresh pod length, 13.1 mm fresh pod width, 75.4 g seed weight per 100 green seed, 39.4% green seed protein content, and 17.3% green seed oil content.

• Korean Journal of Breeding Science
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• v.42 no.6
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• pp.684-689
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• 2010

'Sangwon', a new cultivar for vegetable soybean, was developed from the cross between 'Keunolkong' and 'Oshimamidori', and was released at the National Institute of Crop Science (NICS) in 2007. The goal to develop a vegetable soybean cultivar with green pod, early maturity, large seed size, high yield, lodging tolerance, and resistance to disease such as soybean mosaic virus (SMV). 'Sangwon' has light green pod, early maturity, large seed, short plant height, and lodging tolerance. 'Sangwon' has determinate growth habit, white flower, gray pubescence, and oval leaf shape. The matured seeds have a yellow seed coat with light brown hilum, and a yellow cotyledon. 'Sangwon' has 5.8 cm fresh pod length, 13.2mm fresh pod width, 69.5 g seed weight per 100 green seeds, 44.0% green seed protein content, and 14.8% green seed oil content. At the regional yield trials (RYT) for vegetable soybean from 2005 to 2007, 'Sangwon' shows strong resistance to soybean mosaic virus (SMV) and tolerance to lodging in fields. Fresh pods of 'Sangwon' were harvested at the beginning of August. In the same tests, fresh pod of 'Sangwon' (10.39ton/ha) yielded 5% higher than 'Hwaeomputkong' (9.90ton/ha).

• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.615-623
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• 2020

Brassica rapa is one of the most valuable vegetable crops worldwide. Cultivated varieties of B. rapa exhibit diverse developmental and morphological appearances, which includes important vegetables, oilseeds, and fodder crops. In this study, various phenotypes of recombinant inbred lines (RILs) of B. rapa were investigated, including their responses to five different pathogenic Botrytis cinerea isolates, responses to aphid and thrips during flowering stages, days to flowering, and plant heights. Responses of 113 RILs to five different B. cinerea isolates showed variations, suggesting that genetic factors controlling resistance or tolerance against each isolate were dependent on isolate/genotype pairs. Correlation analysis was performed to understand the nature of genetic factors and the relationship among these phenotypes. Although high levels of correlation were not detected between phenotypes assessed in this study, statistically significant correlation was detected for several combinations. Significant positive correlations were found for different B. cinerea isolates, supporting that certain levels of commonality could exist in genetic components controlling resistance against different B. cinerea isolates. Based on correlation analysis using numbers of insects counted on plants, it was speculated that genetic factors responsible for aphid tolerance or repellence might be also involved in the response against thrips. Relationship between vegetative growth and tolerance against B. cinereal or insects is rather more complicated. However, it was observed that shorter plants appeared to have a certain level of tolerance or repellence against both aphids and thrips. Data presented in this study could be used to assist further genetic studies and breeding efforts to obtain Botritis and insect resistance for B. rapa.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.365-374
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• 2021

White rot or stem rot caused by Sclerotinia sclerotiorum is one of the most destructive fungal diseases that have become a serious threat to the successful cultivation of oilseed Brassicas. The study was designed with an aim to investigate the association between the pathogenic aggressiveness and pathogenicity determinants of this pathogen specifically in Brassica for the first time. For this, a total of 58 isolates of S. sclerotiorum from different geographical regions were collected and purified. These isolates were inoculated on a Brassica juncea cv. RL-1359 and they exhibited high level of variation in their disease progression. The isolates were grouped and then 24 isolates were selected for the biochemical analysis of pathogenicity determinants. The isolates varied significantly with respect to their total organic acids, oxalic acid production and pectin methyl esterase and polygalacturonase activity. The oxalic acid production corresponded to the disease progression of the isolates; the isolates with higher oxalic acid production were the more aggressive ones and vice-versa. This is, in our knowledge, the first study to establish a correlation between oxalic acid production and pathogenic aggressiveness of S. sclerotiorum on B. juncea. However, the pectinases' enzyme activity did not follow the trend as of disease progression. These suggest an indispensable role of oxalic acid in pathogenicity of the fungus and the potential to be used as biochemical marker for preliminary assessment of pathogenic aggressiveness of various isolates before incorporating them in a breeding program.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.424-433
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• 2018

Watermelon (Citrullus lanatus) is an economically important vegetable crop all over the world, which has functional compounds such as lycopene and citrulline. Gummy stem blight caused by Didymella bryoniae is one of the most devastative diseases in watermelon. Single nucleotide polymorphisms (SNPs), which are genetic variations occurring between individuals with respect to a single base, were often used to construct genetic linkage maps and develop molecular markers linked to a variety of horticultural traits and resistance to several diseases. In this study, we developed high-resolution melting (HRM) markers based on SNPs generated from NGS resequencing of two parents in watermelon. Plant materials were C. lanatus '920533' (female and susceptible parent), C. amarus 'PI 189225' (male and resistant parent), and their $F_1$ and $F_2$ progenies. A total of 13.6 Gbp ('920533') and 13.1 Gbp ('PI 189225') of genomic sequences were obtained using NGS analysis. A total of 6.09 million SNPs between '920533' and 'PI 189225' were detected, and 354,860 SNPs were identified as potential HRM primer sets. From these, a total of 330 primer sets for HRM analysis were designed. As a result, a total of 61 HRM markers that have polymorphic melting curves were developed. These HRM markers can be used for the construction of SNP-based linkage maps and for the analysis of quantitative trait loci (QTLs) related to gummy stem blight resistance.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.212-217
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• 2019

Bacterial wilt caused by Ralstonia solanacearum is a major disease that affects tomato plants widely. R. solanacearum is a soil born pathogen which limits the disease control measures. Therefore, breeding of resistant tomato variety to this disease is important. To identify the susceptible variety, degree of disease resistance has to be determined. In this study, micro sap flow sensor is used for accurate prediction of resistant degree. The sensor is designed to measure sap flow and water use in stems of plants. Using this sensor, the susceptibility to bacterial wilt disease can be identified two to three days prior to the onsite of symptoms after innoculation of R. solanacearum. Thus, this find of diagnosis approach can be utilized for the early detection of bacterial wilt disease.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.512-520
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• 2021

In this study, we report genetic characterization of Orobanche cumana, the causal agent of sunflower wilting in Serbia. The genetic diversity of this parasitic plant in Serbia was not studied before. Random amplified polymorphic DNA (RAPD) markers and partial rbcL gene sequences analysis were used to characterize the O. cumana populations at the molecular level. While phylogenetic analyses of RAPD-PCR amplicons were performed using unweighted pair-group Method analyses, rbcL gene sequences were analyzed using neigbor joining method and minimum spanning tree. Molecular analyses of RAPD-PCR analysis revealed high genetic diversity of O. cumana populations which indicated high adaptive potential of this parasitic weed in Serbia. Further analyses of rbcL gene using minimum spanning tree revealed clear differences among diverse sections of Orobanche genus. Although this molecular marker lacked the resolution to display intrapopulation diversity it could be a useful tool for understanding the evolution of this parasitic plant. Our results suggested that O. cumana has great genetic potential which can lead to differentiation of more virulent races which is important for determining crop breeding strategies for their control.

• Journal of Distribution Science
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• v.16 no.8
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• pp.63-68
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• 2018

Purpose - Lettuce (Lactuca sativ L.) is one of the economically important vegetable crops, which worldwide market value is over 100 billion U.S. dollar. In Korea, about 89.7 kilo ton of lettuce was produced in 3400ha in 2016, recoded as No. 1 vegetable crop in domestic green house production. However, recently, domestic lettuce production and cultivation areas are all getting decreased. Thus, novel approaches are needed to be implemented to revive the production. Research design, data and methodology - In this review paper, we first prioritized the end-user traits which are imperative to positively stimulate the domestic lettuce market and discussed relevant genomics strategies. Especially, we assessed a possibility whether school meal program would be a potential niche market. Results - The genomics technologies, which become widely applied in the crop biotechnology since 2008 when next generation sequencing method was developed, may be a good solution in the crop improvement, efficiently gathering valuable information of agriculturally useful traits. Significantly, in lettuce, the high quality whole genome sequence, based on Lactuca sativa cv. Salinas, is publically available and this genomics platform, thus, would be implemented in lettuce breeding program to innovate relevant end-user traits both for the farmers and customers, including the disease resistance to the Fusarium wilt, productivity under hot weather conditions, various nutritional qualities and so forth. These improvements will boost domestic lettuce industries in the near future. Conclusions - Due to the nutritional distinctions comparing to the western style lettuces, domestic leaf lettuces could be one of the important vegetables in the school meal programs. To make it happen, we would better devise diverse recipes to make a salad with it, instead of only using as a wrap vegetable. Meanwhile, novel lettuce varieties need to be developed, which are favorable to the students and also easy to be handled with while processing. Overall, to achieve international competence in the lettuce industries, we need to create elite lettuce varieties that satisfies domestic farmers as well as customers, suitable to various niche markets, such as school meal program. Thus, efficient breeding programs using genomics approaches should be established in advance and careful monitoring on the preference of the related customers for a niche market be continued persistently.