• Horticultural Science & Technology
• /
• v.33 no.5
• /
• pp.722-729
• /
• 2015

Powdery mildew (PM) caused by Podosphaera aphanis is a major disease that can result in significant yield losses in strawberry (Fragaria ${\times}$ ananassa Duchesne). For preventing PM, pesticides are usually applied in strawberry. In this study, molecular markers were developed to increase breeding efficiency of PM-resistance cultivars by marker-assisted selection (MAS). An $F_2$ population derived from a cross between PM-resistance 'Seolhyang' and PM-susceptibility 'Akihime' was evaluated for disease resistance to PM and RAPD (random amplification of polymorphic DNA)-BSA (bulked segregant analysis). Among 200 RAPD primers tested, OPE10 primer amplified a 311bp-band present in with 331bp. Sequence alignment performed for searching polymorphisms and six single nucleotide polymorphism (SNP) were found in amplified regions. To develop polymorphic marker for distinguishing between resistant and susceptible, RAPD was converted to cleaved amplified polymorphic sequence (CAPS) marker. Among restriction enzymes associated with six SNPs, Eae I (Y/GGCCR) was successfully digested to 231bp in susceptible. The results suggest that the selected CAPS marker could be used for increasing efficiency of selecting powdery mildew resistant strawberry in breeding system.

• Journal of Plant Biotechnology
• /
• v.43 no.1
• /
• pp.58-65
• /
• 2016

Powdery mildew is an important disease of the melon (Cucumis melo L.). Seven isolates of powdery mildew fungi were collected from five locations in Korea; Anseong (DH487), Icheon (BN103, BN625, BN968), Yeongam (YA141), Changnyeong (CN582), and Suncheon (SN102). All 7 fungi had a similar trend of conidial chain and conidiophore development as Podosphaera xanthii with fibrosin bodies in mature conidia. Among them, 2 isolates of powdery mildew fungi; CN582 and SN102 showed similar responses to resistance against powdery mildew as the previously reported race 1 and race N2. The isolates YA141 and BN103 showed similar responses as like as race A. However, three isolates of powdery mildew fungi (BN625, BN968, and DH487) showed different responses compared to the previously reported races (1, N1, N2, A, S, and 5). Therefore, these three isolates could be designated as new races in melon. Nine out of 15 commercial melon cultivars in Korea showed resistance to race 1 (CN582). However, the new race BN968 invaded all 15 cultivars. Results of the two molecular markers were consistent in response to disease development by race 1 of Podosphaera xanthii in case of the above mentioned cultivars. This study confirmed the presence of new melon powdery mildew fungi in Korea which are similarly notorious as like as the previously reported race 1. Therefore, breeders can use these two molecular markers for breeding melon in Korea that is resistant to race 1 and as well as to some other races.

• Horticultural Science & Technology
• /
• v.32 no.5
• /
• pp.673-683
• /
• 2014

This study was conducted to establish an efficient screening method to identify cucurbits resistant to powdery mildew. Powdery mildew fungus was obtained from a single lesion of infected cucumber leaf in 2010 at Daejeon. The fungus was identified as Podosphaera xanthii race 1 based on morphological characteristics and resistance responses of four melon differentials. Development of powdery mildew caused by the fungal isolate on 34 commercial cultivars of cucumber was investigated at three plant growth stages in a greenhouse. The degree of resistance of cotyledons of each cultivar to the fungus was not correlated with that of whole plant, but powdery mildew occurrence in the first true leaf was highly correlated with resistance at the level of the whole plant. Based on these results, the first true leaf of cucurbit cultivars can be used for screening of resistance to powdery mildew. In addition, variation of resistance of commercial 12 cucumber and 26 melon cultivars to the powdery mildew fungus due to different growing seasons was tested. In the case of cucumber, the resistance response in some cultivars was influenced by growing season. The resistant cultivars showed higher resistance in the warm season than in the cool season. By contrast, the resistant melon cultivars demonstrated strong resistance in all the tested growing seasons. Interestingly, the tested powdery mildew pathogen, a member of P. xanthii race 1, was not pathogenic on seven cultivars of watermelon (Citrullus lanatus). To follow up on this, diverse race 1 isolates of P. xanthii should be collected and tested.

• Research in Plant Disease
• /
• v.14 no.2
• /
• pp.95-101
• /
• 2008

Fungicide resistance of cucumber powdery mildew was screened among the pathogens isolated from diseased plants in main cucumber productuion areas in Gyeonggi Province. Each fungicide from different activity group for the control of powdery mildew were sprayed on cucumber leaves according to application concentration. Each conidia mixed with sterilized water isolated of pathogens were transferred on the cucumber leaf disks treated with each fungicide. At 7 to 9 days after inoculation of pathogen, disease severity was recorded under the microscope. Most of pathogen isolates showed moderate resistance to difenoconazole belonged to DMI group fungicide while some isolates from Osan were resistant even $300{\mu}g/ml$. Isolates from Pyeongtaek, Osan and Yongin area also showed moderate resistance to fenarimol while one isolate showed resistant to fenarimol even $300{\mu}g/ml$. Most of isolates from Pyeongtaek, Osan and Yongin showed highly resistant to azoxystrobin belonged to strobilurin group fungicide. Standard sensitive isolates the minimum inhibition concentration(MIC) value for azoxystrobin showed $200{\mu}g/ml$ while resistance isolates showed above $2000{\mu}g/ml$. Resistant isloates also showed cross resistance among strobilurin group fungicides and low control efficacy in the field test. These results suggest that treatment of strobilurin fungicides should be reduced for the control of powdery mildew.

• Research in Plant Disease
• /
• v.17 no.3
• /
• pp.311-316
• /
• 2011

Pepper powdery mildew causes increasingly economical damage due to increased cultivation of pepper in greenhouses. To assess resistance of pepper resources against pepper powdery mildew, we developed a novel evaluation formula for pepper resistance against powdery mildew. The evaluation formula named S index is as follows; (number of the highest disease leaf/top leaf number)-(number of the lowest disease leaf/top leaf number). Positive correlation (81%, P = 0.01) between S index and authentic disease leaf rate was observed from the pepper plants infected by powdery mildew. Various pepper species from our genetic resources were evaluated to identify pepper varieties conferring resistance against powdery mild using S-index. Capsicum frutescens accessions 3CA131 and C. baccatum accessions 3CA0162, 3CA174, 3CA176 showed high resistance to powdery mildew, but none of C. annuum was resistant. Results suggest that S-index proposed in this study is useful to assess resistance evaluation of powdery mildew in chili pepper breeding.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.4
• /
• pp.35-37
• /
• 1979

To investigate the genetic system in resistance to powdery mildew winter wheat cultivar Diplomat which has stable field resistance was crossed with high yielding susceptible winter type Caribo and Hayman's generation mean analysis technique was employed. Mildewing rate on flag-leaf at both heading-flowering and ripe stages were recorded according to lame's quantitative scale. The result indicated that additive gene effect was more important and significant role in the inheritance of resistance while dominant gene effect was minimum, and digenic interations were absent. Narrow sense heritability of resistance at ripe stage was higher than that of heading-flowering stage.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2021.04a
• /
• pp.17-17
• /
• 2021

곰취는 주로 쌈용, 장아찌, 나물용 등으로 이용되고 있으며 주로 자생 곰취의 일종인 '곤달비' 라고 하는 종이 많이 재배되고 있다. 일반 곰취에 비해 곤달비는 향이 진하지 않고 씁쓸한 맛이 적어 인기가 많은 종이다. 또한 농가에서는 엽수가 많아 수량이 높기 때문에 재배를 선호하게 된 종이기도 하다. 그러나 곤달비는 수확후 여름을 지나면서 고온건조기에 흰가루병과 식물체가 위축되는 로젯현상으로 잎이 작고 진록색으로 되거나 고사하여 다음해의 수량을 저하시키는 원인이 되고 있다. 이렇게 2~3년 재배를 하면 연작장애와 더불어 결주가 생기기 시작하고 수량이 급격히 감소하는 문제가 발생되는 실정이다. 이러한 문제점을 해결하기 위하여 흰가루병에 저항성이면서 세력이 우수한 한대리곰취와 일반곰취를 교배하여 흰가루병에 강하고 수량성이 뛰어난 계통을 선발하여 그 동안 '쌈마니', '다목이', '곰마니', '수마니', '그린베어' 등 5품종을 육성한 바 있다. 이번에는 용도 다양화를 위하여 잎이 매우 커서 김밥처럼 곰취 밥말 이용을 선발하여 품종을 만들고자 하였다. '대마니' 품종은 2007년 7월에서 9월까지 인공교배를 하여 종자를 얻었으며 2008년 3월에 파종하여 육묘후 포장에 정식하여 생육관리를 하였다. 2013년 생육 및 수량특성 조사에서 일반적으로 많이 재배되는 '곤달비' 종보다 우수한 7033-1번 개체를 선발하였다. 선발된 7033-1번 개체는 2014년부터 2020년까지 노지포장에서 증식되면서 고농G-7호로 계통화 되었으며 2019년부터 2년간의 생육특성 검정을 통하여 최종 선발하였다. 그리고 2020년 농작물직무육성 품종선정위원회에서 신품종으로 선정되어 '대마니(Daemani)'로 명명되었다. '대마니' 품종의 특성은 엽병귀의 색이 연녹색을 띠고 엽병에 털이 있으며 잎 뒷면에 털은 없으나 광택이 없고. 엽맥밀도는 보통이다. 쌈용, 데침쌈용, 묵나물용으로 이용이 가능하다. 특히 엽장과 엽폭이 39cm와 49cm로 '잎이 커서 밥말이용으로 적당하다. 주당 엽수는 54개로 '쌈마니' 품종보다 매우 적다. 주당 수량은 4,961g 으로 '쌈마니' 1,362g 보다 3배 정도 많았다. 추대시는 8월 28일, 개화시는 9월 16일로 '쌈마니' 품종보다 약 6일 정도 늦었다. 흰가루병 저항성 정도는 '쌈마니' 품종의 중도 저항성에 비하여 전혀 병에 감염되지 않는 강한 저항성을 보였다. 이와 같은 특성의 흰가루병 저항성 품종이고 잎이 큰 '대마니' 품종이 농가에 보급되어 출하된다면 밥말이용 등 용도다양화를 통한 새로운 소비창출이 가능할 것으로 기대된다.

• Horticultural Science & Technology
• /
• v.30 no.2
• /
• pp.185-191
• /
• 2012

For initiation of resistance breeding program of the red pepper, 21 PR ($Phytophthora$ resistance) cultivars, 36 cultivars collected from USA and 'Supermanitta' which is a susceptible cultivar against phytophthora blight were assayed against phytophthora blight, powdery mildew, and anthracnose. For seedling assay of phytophthora blight, three different mating type strains of $Phytophthora$ $capsici$ were used (A1, A2, Sterile). The result showed that most of the pepper of PR cultivars were resistance or moderately resistance at each mating type. 'Yeokganghongjanggun' was resistant to all three $P.$ $capsici$ strains and 'PR-Datta' and 'PR-Manitta' were resistant or moderately resistant at each type. In case of the collected cultivars, 'NuMex J.E.Parker', 'Omni Color', and 'SCM334' were resistant to all the three types and some cultivars including 'Sweet Banana' and 'Tabasco' were moderately resistant to each type fungi. 'Orange Habanero' and 'Black Cuban' were resistant to powdery mildew and 'Supermanitta' and 'PR Keumdong' were moderately resistant, while 'Santa Fe Grande', 'NuMex Pinata' and 'Puya' were very susceptible. In the case of anthracnose, 'Aji Limon' and 'Capsicum baccatum var. pendulum 3-4' were resistant and 'Pobalno', 'Omni Color', 'Negro', 'Mesilla', 'Mulato', 'Bhut Jolokia', 'Big Dipper', 'Black Cuban', 'NuMex Pinata', and 'NuMex Big Jim' were moderately resistant. The most PR cultivars except 'Taesan' were susceptible or very susceptible. These resistant individuals identified through this experiment can be used as sources of resistance to pepper pathogens in the future breeding programs.

• Research in Plant Disease
• /
• v.18 no.1
• /
• pp.29-34
• /
• 2012

Powdery mildew and root-knot nematode are very important diseases occurred in cucurbits. This study was conducted to evaluate the resistance of commercial cucurbit cultivars (21 cultivars of cucumber, 9 cultivars of watermelon, 7 cultivars of oriental melon, and 2 cultivars of melon) to powdery mildew and root-knot nematode. At 60 days after transplanting, disease severity of powdery mildew of commercial cucurbit cultivars was investigated. Two cucumber cultivars, 'Gangryeogsamcheok' and 'Sunhobaegchimdadagi' were moderately resistant but the rest of cucumber cultivars were susceptible to powdery mildew. All examined watermelon and oriental melon cultivars were susceptible to powdery mildew, while two melon cultivars ('PMR Turbo' and 'PMR Victory') were resistant. At 45 days after inoculation of seedlings, disease severity of root-knot nematode of commercial cucurbit cultivars were investigated. One cucumber cultivars, 'Baegbongdadagi' was moderately resistant and the others were susceptible to root-knot nematode. In case of watermelon, 'Dalgonakkul' was resistant and the others were moderately resistant or susceptible to root-knot nematode. All examined oriental melon and melon cultivars were susceptible to root-knot nematode. On these results, we recommend that resistant cultivars to powdery mildew and/or root-knot nematode will be more suitable in cultivation of cucurbits for organic farming.

• Research in Plant Disease
• /
• v.10 no.1
• /
• pp.78-81
• /
• 2004

The resistance of 10 varieties of cucumber (Cucumis sativus L.) to powdery mildew, caused by Sphaerotheca fusca, was evaluated by a leaf disk assay. Leaf disks (10 mm in diameter) were removed from fully expanded leaves and then placed in petri dishes containing 0.16％ water agar amended with benzimidazole. Leaf disks were inoculated by dropping a 10 $\mu$l of conidia suspension. Conidiophore formation of powdery mildew was the greatest at $25^{\circ}C$. The response of the host to powdery mildew, based on the inoculation onto disks of the first leaf, highly correlated with results obtained from harvesting stage of cucumber plants in greenhouse test (r = 0.99$^{**}$). It is indicating that a leaf disk assay may precisely predict the response of cucumber plant to S. fusca.a.