• The Plant Pathology Journal
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• v.32 no.1
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• pp.65-69
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• 2016

In plant virus ecology, weeds are regarded as wild reservoirs of viruses and as potential sources for insect-mediated transmission of viruses. During field surveys in 2013-2014, three Leonurus sibiricus plants showing virus-like symptoms were collected from pepper fields in Daegu, Seosan, and Danyang in Korea. Molecular diagnosis assays showed that the collected L. sibiricus samples were infected with either Tomato spotted wilt virus (TSWV), Pepper mild mottle virus (PMMoV), or Beet western yellow virus (BWYV), respectively. Since this is the first identification of TSWV, PMMoV, and BWYV from L. sibiricus, complete genome sequences of three virus isolates were determined to examine their phylogenetic relationships with the previously reported strains and isolates. Phylogenetic analyses performed using full genome sequences of the viruses showed the isolates of TSWV and PMMoV obtained from L. sibiricus are closely related to the pepper isolates of the corresponding viruses. Our results suggest that L. sibiricus could act an alternative host and reservoir of viruses that cause damages in pepper fields.

• The Plant Pathology Journal
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• v.36 no.1
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• pp.67-75
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• 2020

Tomato spotted wilt virus (TSWV) is one of the plant viruses transmitted by thrips and causes severe economic damage to various crops. From 2008 to 2011, to identify natural host species of TSWV in South Korea, weeds and crops were collected from 5 regions (Seosan, Yesan, Yeonggwang, Naju, and Suncheon) where TSWV occurred and were identified as 1,104 samples that belong to 144 species from 40 families. According to reverse transcription-polymerase chain reaction, TSWV was detected from 73 samples from 23 crop species, 5 of which belonged to family Solanaceae. Additionally, 42 weed species were confirmed as natural hosts of TSWV with three different life cycles, indicating that these weed species could play an important role as virus reservoirs during no cultivation periods of crops. This study provides up-to-date comprehensive information for TSWV natural hosts in South Korea.

• Weed & Turfgrass Science
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• v.7 no.1
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• pp.54-61
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• 2018

Zoysiagrass (Zoysia spp.) exists spotly in Indonesia and it has potential to be used in parks, golf courses, and football fields. Many football fields and golf course fairways use sand as top soil over native soil. This study aims to analyze growth and quality of two native zoysiagrasses Zis and Zim. Zis is a native zoysiagrass collected in sea-side and Zim is a native zoysiagrass collected in mountain area. Both types of zoysiagrasses were planted at field with altitude of 300 m with various growing media mixes of sand and reservoir's sediment. Thickness of the growing medium was 10 cm over an alfisol clay soil. Experimental plots were constructed using factorial completely randomized design with two native zoysiagrasses and 5 types of growing media. Two ecotypes of native zoysiagrasses showed different in growth habits combined with mixtures of growth media. Zim showed higher growing speed including more vigor with uniformity and texture than Zis. There were not significanthly differences on leaf color and root length between two ecotypes of native zoysiagrasses collected in Indonesia.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.118-123
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• 2015

Metagenomics is a powerful tool to isolate novel biocatalyst and biomolecules directly from the environmental DNA libraries. Since the metagenomics approach bypasses cultivation of microorganisms, un-cultured microorganisms that are majority of exists can be the richest reservoir for natural products discovery. To discover novel herbicidal substances from soil metagenome, we established three easy, simple and effective high throughput screening methods such as cucumber cotyledon leaf disc assay, microalgae assay and seed germination assay. Employing the methods, we isolated two active single clones (9-G1 and 9-G12) expressing herbicidal activity which whitened leaf discs, inhibited growth of microalgae and inhibited root growth of germinated Arabidopsis seeds. Spraying butanol fraction of the isolated active clones' culture broth led to growth retardation or desiccation of Digitalia sanguinalis (L) Scop. in vivo. These results represent that the screening methods established in this study are useful to screen herbicidal substances from metagenome libraries. Further identifying molecular structure of the herbicidal active substances and analyzing gene clusters encoding synthesis systems for the active substances are in progress.

• Research in Plant Disease
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• v.19 no.4
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• pp.281-287
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• 2013

In surveys of weed occurrence undertaken from 2006 to 2007, near to the Daegu experimental fields of the National Institute of Crop Science, plants belonging to 31 families, 74 genera and 96 species were found. For the investigation of the natural or alternative hosts of Soybean yellow mottle mosaic virus (SYMMV), 495 plant samples belonging to 26 families 84 species were subjected to RT-PCR. SYMMV was detected only from legume plants such as Glycine soja, Vigna angularis var. nipponensis, Trifolium repens, and Lespedeza cuneata. Among legume plants tested, more than a third of G. soja (wild soybean) contained SYMMV, indicating that the wild soybean played an important role as a reservoir of SYMMV. Wild soybeans may be infected with SYMMV as early as mid-July. Considering the results of early infection and the high infection rate of seed and seed transmission of SYMMV in G. soja, wild soybeans may have played an important role in the completion of disease cycle of the virus.

• Research in Plant Disease
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• v.22 no.1
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• pp.25-31
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• 2016

During a field survey in 2014, a Rorippa palustris plant showing virus-like symptom was collected from a pepper field in Dangjin in Korea. The collected sample was subjected to examine infection with pepper-infecting viruses. Molecular diagnosis assay showed that the collected R. palustris sample was co-infected with Pepper mild mottle virus (PMMoV) and Cucumber mosaic virus (CMV). This is the first identification of PMMoV from R. palustris and the first report of CMV infection of R. palustris in Korea. To examine phylogenetic positions of the identified PMMoV and CMV isolates, their complete genome sequences of were determined and compared with those of previously reported isolates of the cognate viruses. Phylogenetic analyses revealed the isolates of PMMoV and CMV obtained from R. palustris are closely related to the pepper isolates of the cognate viruses. Our results suggest that R. palustris could act a weed reservoir of PMMoV and CMV.