Identification of Strains and Inheritance of Pathogenicity in Phytophthora capsici

Polach, F. J.; Webster, R. K.

doi:10.1094/phyto-62-20

Cited by 51 publications

(22 citation statements)

References 3 publications

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“…It has been previously suggested that other species such Phytophthora parasitica var. nicotianae lose virulence in culturing (Apple 1957), and it has been noted that some P. capsici isolates that have been sub-cultured for many years are nonpathogenic or weakly virulent (Aragaki and Uchida 2001;Kim and Hwang 1992;Lee et al 2001;Polach and Webster 1972). Since at least some P. tropicalis and intermediate isolates were pathogenic to each of the hosts included in this study, pathogenicity to cucumber, tomato, zucchini, or pepper fruits should not be used to separate P. tropicalis from P. capsici isolates.…”

Section: Discussionmentioning

confidence: 99%

“…It has been understood since the 1970s (Polach and Webster 1972) that P. capsici populations may differ in pathogenicity, but whether or not virulence may be associated with other isolate characteristics is unknown. Interestingly, when 24 P. capsici isolates from processing pumpkin were used to inoculate pumpkin seedlings, isolates grouped into six virulence groups, which corresponded directly with six random amplified polymorphic DNA (RAPD) groups (Islam et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Differences in virulence of Phytophthora capsici isolates from a worldwide collection on host fruits

2011

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Phytophthora capsici causes root, crown, and fruit rot of vegetable and tropical hosts. Cucumber, zucchini, tomato, and pepper fruits were inoculated using 6-mm-diameter agar plugs of P. capsici, incubated in clear plastic boxes at room temperature (25±2°C and 100% relative humidity), and virulence was estimated by measuring the lesion diameter, pathogen growth diameter, and pathogen sporulation density three (cucumber, zucchini) or four (tomato, pepper) days later. When isolates were grouped by genetic cluster, significant differences in virulence were observed on cucumber and zucchini, with isolates belonging to genetic cluster five causing larger lesions than isolates from genetic cluster six. On tomato, no significant differences were observed for isolates grouped by genetic cluster, but isolates from vegetable crops were generally more virulent than isolates from tropical hosts. Isolates from fabaceous hosts sporulated better on cucumber fruits than isolates from solanaceous hosts. Isolates from vegetable hosts sporulated better on zucchini than isolates from tropical hosts. No significant differences in lesion diameter were noted on pepper when isolates were grouped by host family of origin or genetic cluster, but differences in pathogen sporulation were apparent by host family. Our findings suggest that isolate characteristics such as host family of origin and genetic cluster membership may be used to guide initial isolate selection for cucurbit fruit resistance screening. Final isolate selection should incorporate the phenotypic and genetic diversity of P. capsici, including isolates with differing virulence to the host organ of interest.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Differences in virulence of Phytophthora capsici isolates from a worldwide collection on host fruits

2011

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“…This resistance was later reported to be governed by two, distinct, dominant genes that act independently without additive effects [Smith et al, 1967;Polach and Webster, 1972], or by a single, dominant gene with modifiers [Barksdale, 1984]. However, prolonged incubation periods or very high inoculum concentrations ofP.…”

Section: Introductionmentioning

confidence: 99%

“…Polach and Webster [1972] defined 14 pathogenic strains of P. capsici based on pathogenicity to different hosts, but not to different pepper cultivars. In their study, recombination between pathogenicity and mating type occurred, based on 391 single-oospore progenies from crosses of A 1 and A2 types.…”

Section: Introductionmentioning

confidence: 99%

Differential interactions ofPhytophthora capsici isolates with pepper genotypes at various plant growth stages

Hwang

Kim

1996

Eur J Plant Pathol

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Pepper cultivars from diverse geographic origins were evaluated for resistance to different isolates of Phytophthora capsici under controlled environmental conditions. All accessions tested were susceptible at the four-leaf stage to the six isolates of P. capsici. Inoculation at the eight-leaf stage resulted in significantly different interactions among the accessions and P. capsici isolates. The Korean and U.S. cultivars tested were highly susceptible to the isolates ofP. capsici at this stage. In contrast, PI 201234 and PI 201238 had a differential interaction with some P. capsici isolates. At the twelve-leaf stage, Phytophthorablight developed slowly in the Korean and U.S. cultivars that were highly susceptible at the eight-leaf stage. Furthermore, the accessions from the Asian Vegetable Research and Development Center (AVRDC) became highly resistant to P. capsici at this stage.

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“…고추 역병에 대한 유전자원들의 저항성에 관한 연구가 모두 이해된 것은 아니다. 처음에는 독립적으 로 작용하는 2개의 우성유전자에 의해 (Polach and Webster, 1972;Smith et al, 1967) 혹은 modifier와 함께 단일 우성 유전자 (Barksdale et al, 1984)가 저항성을 나타낸다고 하였 으나, 최근에는 고추의 역병 저항성을 질적 저항성보다는 chromosome 4, 5, 6, 11 및 12에 존재하는 6개 영역이 저항 성을 책임지는 QTL 저항성으로 인식하고 있다 (Lefebvre and Palloix, 1996;Lefebvre et al, 2002;Pflieger et al, 2001;Thabuis et al, 2003Thabuis et al, , 2004. 또한 고추의 역병 저항성은 접 종원 농도와 배양시간에 따라 영향을 받으며, 또 고추의 생 육시기가 증가할수록 저항성 발현이 뚜렷하게 증가한다고 알려져 있어 이를 뒷받침한다 (Barksdale et al, 1984;Hwang, 2002;Kim et al, 1989).…”

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Resistance of Chili Pepper Cultivars to Isolates of Phytophthora capsici

Jo¹,

Shim²,

Jang³

et al. 2014

HST

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Resistance of one hundred commercialized cultivars of chili pepper to four isolates of Phytophthora capsici was evaluated under controlled environmental conditions. The cultivars are commercialized as resistant (59%) and susceptible (41%) to Phytophthora blight in Korea. Mean disease severities of the cultivars on P. capsici MY-1, KPC-1, JHAI1-7, and KPC-7 isolates were 37, 55, 60, and 74%, respectively. In addition, 38 for MY-1, 48 for KPC-1, 56 for JHAI1-7, and 76 cultivars for KPC-7 showed susceptibility. To P. capsici MY-1, the weakest pathogenicity isolate among them, 59 cultivars represented high resistance. By contrast, only six cultivars showed high resistance to P. capsici KPC-7, the strongest isolate. Furthermore, resistance of most cultivars except for three cultivars was negatively correlated with the virulence of P. capsici isolates. And isolate-specific resistance of the chili pepper cultivars could not be found. Among them, six cultivars showing resistance to all the tested isolates were selected for further study. The development of Phytophthora blight on the six cultivars according to inoculum density (5 × 10 4 to 1.5 × 10 6 sporangia/pot) and incubation temperature (25 to 30°C) after inoculation of P. capsici was tested. Resistance of the cultivars to P. capsici KPC-1 and JHAI1-7, moderately pathogenic isolates, was hardly affected. But to KPC-7 isolate, the highly resistant cultivars showed susceptiblility or moderate resistance when the seedlings were inoculated with inoculum density of 1.5 × 10 6 sporangia/pot and incubated at 28 to 30°C. From these results, it is likely that resistance of chili pepper cultivars to Phytophthora blight is affected by the virulence of P. capsici isolate.

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Identification of Strains and Inheritance of Pathogenicity in Phytophthora capsici

Cited by 51 publications

References 3 publications

Differences in virulence of Phytophthora capsici isolates from a worldwide collection on host fruits

Differences in virulence of Phytophthora capsici isolates from a worldwide collection on host fruits

Differential interactions ofPhytophthora capsici isolates with pepper genotypes at various plant growth stages

Resistance of Chili Pepper Cultivars to Isolates of Phytophthora capsici

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