Pepper mild mottle virus (PMMoV), a member of the genus Tobamovirus, is one of the most threatening pathogens affecting commercial pepper production, and it is classified into pathotypes P1,2 and P1,2,3. As chemical and physical treatments show limited success in controlling PMMoV, resistant pepper varieties are considered the most effective means of disease control. Two hundred pepper germplasms, including 167 accessions of Capsicum chinense and 5 reference accessions known as resistant L alleles, were assessed using a bioassay to select germplasms resistant to PMMoV. Six accessions, including IT261210, were resistant to both PMMoV pathotypes P1,2 and P1,2,3 as they developed necrotic local lesions only on inoculated leaves, whereas no symptoms were observed on the upper leaves. Moreover, RT-PCR results of the upper leaves of these accessions were also negative. Thus, the identified accessions may be a novel source of genetic resistance against present or emerging new pathotypes and may be useful for differentiating L alleles.
Identification of Fusarium oxysporum f. sp. raphani and investigation on fusarium wilt development by isolates and inoculation methods were conducted to establish a screening method for fusarium wilt-resistance in radish (Raphanus sativus L.) germplasm. Pathogenicity of F. oxysporum f. sp. raphani isolate, Heonggye-1 and Heonggye-2, to radish plants was confirmed by seedling test. Radish seedlings were inoculated by root-dipping and soil-drenching with or without root-wounding. For Heonggye-1 isolate, mean disease indexes were 4.13 and 3.91 by root-dipping and soil-drenching with root-wounding, respectively, but those were 1.87 and 1.88 without root-wounding. For Heonggye-2 isolate, mean disease indexes were 3.83 to 4.37 regardless of inoculation methods. Two-hundred sixty accessions of radish germplasm collected from 9 countries of Asia and Europe were evaluated for fusarium wilt-resistance by soil-drenching with root-wounding with Heonggye-2 isolate. Fifty-four resistant accessions with higher than 70% of the percentage of resistant seedlings in accession (PR) and lower than 20% of the percentage of susceptible seedlings in accession (PS) was found. Eighteen susceptible accessions with lower than 20% of PR and higher than 50% of PS were selected. These accessions could be used as breeding and research materials after re-evaluation of disease-resistance and characterization of agronomical traits.