scholarly journals An Inexpensive Disease Screening Technique for Foliar Blight of Chile Pepper Seedlings

HortScience ◽  
1994 ◽  
Vol 29 (10) ◽  
pp. 1182-1183 ◽  
Author(s):  
Tito P. Alcantara ◽  
Paul W. Bosland
Keyword(s):  
Root Rot ◽  
Fungal Pathogen ◽  
Phytophthora Capsici ◽  
Symptom Development ◽  
Sources Of Resistance ◽  
Screening Technique ◽  
Land Race ◽  
Foliar Blight ◽  
Leaf Surfaces ◽  
Test Plants

An inexpensive, rapid, and reliable seedling screening technique was developed to identify sources of resistance to foliar blight of Capsicum annuum L. caused by the fungal pathogen Phytophthora capsici Leon. Leaf surfaces of test plants were inoculated with 500 to 1000 zoospores prepared in distilled water. Seedlings were incubated for 5 days in an easy-to-construct dew chamber and observed for symptom development. `Criollo de Morelos 334' chile seedlings, a Mexican land race resistant to root rot caused by the same fungal pathogen, were highly resistant to foliar blight. All commercial cultivars tested in this study, however, were highly susceptible. No root rot symptoms were observed in any of the foliar-inoculated plants.

scholarly journals Phytophthora Root Rot Resistance and Its Correlation with Fruit Rot Resistance in Capsicum annuum

HortScience ◽  
2020 ◽  
Vol 55 (12) ◽  
pp. 1931-1937
Author(s):  
Rachel P. Naegele ◽  
Mary K. Hausbeck
Keyword(s):  
Broad Spectrum ◽  
Root Rot ◽  
Partial Resistance ◽  
Phytophthora Capsici ◽  
Fruit Rot ◽  
Multiple Sources ◽  
Sources Of Resistance ◽  
Phytophthora Root Rot ◽  
Foliar Blight ◽  
Moderate Resistance

Phytophthora capsici causes root and fruit rot and foliar blight of pepper. Multiple sources of resistance to Phytophthora root rot have previously been identified, but most display only partial resistance. One source, CM334, has broad spectrum root rot resistance to multiple pathogen isolates but has only low to moderate fruit rot resistance. This study evaluated previously identified pepper lines for resistance to two P. capsici isolates, OP97 and 12889, and compared root rot resistance to fruit rot resistance and genetic structure. CM334 was confirmed as a broad spectrum resistance genotype, whereas all other sources of resistance evaluated were susceptible to infection by one or both isolates evaluated. Although not completely resistant, PI 566811 displayed moderate resistance to fruit and root rot to both P. capsici isolates. Fruit rot resistance had a significant but small to moderate positive correlation (r = 0.26–0.63) with root rot resistance depending on the isolate and length of exposure. Pepper accessions with resistance to Phytophthora root and fruit rot belonging to different genetic subpopulations were identified and could serve as candidates for partial-resistance loci to incorporate into pepper breeding programs.

scholarly journals A Rapid Technique for Multiple-race Disease Screening of Phytophthora Foliar Blight on Single Capsicum annuum L. Plants

HortScience ◽  
2010 ◽  
Vol 45 (10) ◽  
pp. 1563-1566 ◽  
Author(s):  
Ariadna Monroy-Barbosa ◽  
Paul W. Bosland
Keyword(s):  
Capsicum Annuum ◽  
Root Rot ◽  
Recombinant Inbred Lines ◽  
Phytophthora Capsici ◽  
Pepper Plant ◽  
Phytophthora Blight ◽  
Chile Pepper ◽  
Physiological Races ◽  
Foliar Blight

Phytophthora blight, caused by the oomycete Phytophthora capsici Leon., is a major disease that threatens production and long-term viability of the chile pepper (Capsicum annuum L.) industry. For each phytophthora disease syndrome such as root rot, foliar blight, and stem blight separate and independent resistant systems have evolved in the host. In addition, several physiological races of the pathogen have been identified. A novel, effective, and accurate screening technique is described that allows for multiple races to be evaluated on a single plant of C. annuum. The P. capsici resistant line Criollo de Morelos-334, a susceptible cultivar, Camelot, and three New Mexico Recombinant Inbred Lines, -F, -I, -S, were used to evaluate the new technique for phytophthora foliar blight multiple-race screening. Using three P. capsici physiological races, no interaction among the physiological races was observed with this technique. This novel technique provided a rapid disease screen evaluating multiple physiological races for phytophthora foliar blight resistance in a single chile pepper plant and can assist plant breeders in selecting for disease-resistant plants.

Ultrastructural changes in roots of peppers resistant and susceptible to Phytophthora capsici

1995 ◽  
Vol 53 ◽  
pp. 982-983
Author(s):  
H. Ilarslan ◽  
A.S. Ustun ◽  
R. Yilmazer
Keyword(s):  
Root Rot ◽  
Host Plants ◽  
Phytophthora Capsici ◽  
Host Cells ◽  
Ultrastructural Changes ◽  
Ultrastructural Examination ◽  
Susceptible Host ◽  
Ultrastructural Studies ◽  
Foliar Blight ◽  
Crown And Root Rot

The infection by Phytophthora capsici Leonian causes foliar blight and crown and root rot of pepper plants. The ultrastructural examination of resistant and susceptible host-pathogen interactions was conducted in the pepper cultivars Ince Sivri-35, PM217, and PM702=CM 334 following inoculation with Phytophthora capsici. Responses were characterized and compared with healthy non-inoculated controls at 2,4 and 6 days after inoculation. Numerous ultrastructural studies have been made of the interaction of various host plants Phytophthora spp. No ultrastructural studies comparing the resistant and susceptible reactions of pepper cultivars to P. capsici. have been reported. It is important to examine the ultrastructural changes in inoculated and infected tissue of resistant and susceptible pepper cultivars to P. capsici. Information reported here characterizes the processes of pathogen containment in resistant interactions and compares these with the processes occuring in susceptible interactions.After 2 days in susceptible interactions, the pathogen grew intercellularly in roots, whereas in resistant interactions only a few intercellular hyphae were observed penetrating the host cells and forming haustoria.

scholarly journals Inheritance of Phytophthora Root Rot and Foliar Blight Resistance in Pepper

1999 ◽  
Vol 124 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Stephanie J. Walker ◽  
Paul W. Bosland
Keyword(s):  
Root Rot ◽  
Phytophthora Capsici ◽  
Dominant Gene ◽  
Segregation Ratio ◽  
Stem Cutting ◽  
Blight Resistance ◽  
Phytophthora Root Rot ◽  
Resistant Parent ◽  
Foliar Blight ◽  
Foliar Resistance

The inheritance of resistance to Phytophthora capsici Leonian root rot and foliar blight was compared in two different Capsicum annuum L. var. annuum pod types. The seedling was screened for phytophthora root rot, while a genetically identical stem cutting was screened for phytophthora foliar blight to determine if the same gene(s) confer resistance to both disease syndromes. The susceptible parents were `Keystone Resistant Giant #3' (`Keystone'), a bell pepper type, and `Early Jalapeño', while `Criollo de Morelos-334' was the resistant parent. Resistance was observed in both F1 populations screened for phytophthora root and foliar infection indicating dominance for resistance. Reciprocal effects were not detected. To determine if the same gene(s) conferred root rot and foliar resistance, root rot screening results were matched to the corresponding foliar blight stem cutting reaction. The segregation of resistance in the F2 generations was dependent on the susceptible parent. In the F2 generation derived from `Early Jalapeño', root rot resistance and foliar blight resistance segregated in a 9:3:3:1 (root resistant/foliar resistant: root resistant/foliar susceptible: root susceptible/foliar resistant: root susceptible/foliar susceptible) ratio. One independent, dominant gene was necessary for root rot resistance, and a different independent, dominant gene was needed for foliar blight resistance. In the F2 generation derived from `Keystone', root rot and foliar blight resistance segregated in a 7:2:2:5 (root resistant/foliar resistant: root resistant/foliar susceptible: root susceptible/foliar resistant: root susceptible/foliar susceptible) ratio. This segregation ratio is expected when one dominant gene is required for root resistance, and a different dominant gene is required for foliar resistance. In addition to these two genes, at least one dominant allele of a third gene must be present for expression of root rot and foliar blight resistance.

scholarly journals Screening of Cucurbita moschata Duchesne Germplasm for Crown Rot Resistance to Floridian Isolates of Phytophthora capsici Leonian

HortScience ◽  
2011 ◽  
Vol 46 (4) ◽  
pp. 536-540 ◽  
Author(s):  
Dario J. Chavez ◽  
Eileen A. Kabelka ◽  
José X. Chaparro
Keyword(s):  
Root Rot ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Fruit Rot ◽  
Cucurbita Moschata ◽  
Breeding Lines ◽  
Foliar Blight ◽  
Disease Rating ◽  
Crown And Root Rot ◽  
Highly Virulent

Phytophthora capsici causes seedling death, crown and root rot, fruit rot, and foliar blight on squash and pumpkins (Cucurbita spp. L.). A total of 119 C. moschata accessions, from 39 geographic locations throughout the world, and a highly susceptible butternut squash cultivar, Butterbush, were inoculated with a suspension of three highly virulent P. capsici isolates from Florida to identify resistance to crown rot. Mean disease rating (DR) of the C. moschata collection ranged from 1.4 to 5 (0 to 5 scale with 0 resistant and 5 susceptible). Potential resistant and tolerant individuals were identified in the C. moschata collection. A set of 18 PIs from the original screen were rescreened for crown rot resistance. This rescreen produced similar results as the original screen (r = 0.55, P = 0.01). The accessions PI 176531, PI 458740, PI 442266, PI 442262, and PI 634693 were identified with lowest rates of crown infection with a mean DR less than 1.0 and/or individuals with DR = 0. Further selections from these accessions could be made to develop Cucurbita breeding lines and cultivars with resistance to crown rot caused by P. capsici.

scholarly journals Screening Capsicum annuum Accessions for Resistance to Six Isolates of Phytophthora capsici

HortScience ◽  
2010 ◽  
Vol 45 (2) ◽  
pp. 254-259 ◽  
Author(s):  
Byron L. Candole ◽  
Patrick J. Conner ◽  
Pingsheng Ji
Keyword(s):  
Capsicum Annuum ◽  
Root Rot ◽  
Phytophthora Capsici ◽  
Bell Pepper ◽  
Initial Screening ◽  
Phytophthora Blight ◽  
Sources Of Resistance ◽  
Potential Sources ◽  
Bell Peppers ◽  
Seed Increase

Phytophthora blight caused by Phytophthora capsici Leon. is one of the most important diseases of bell peppers (Capsicum annuum L.) in Georgia. The level of resistance in commercial bell pepper cultivars is not effective in managing this disease in moist and humid conditions, and new sources of resistance are needed. A mixture of six Georgia isolates of P. capsici was used for greenhouse mass screening of 2301 accessions of Capsicum annuum. From the initial screening, 77 accessions were identified as resistant to P. capsici-induced root rot. From those 77 accessions, 28 accessions were selected for seed increase and further replicated root inoculation tests. Replicated tests confirmed the resistance of 14 of the 28 accessions, although genetic variability within the accessions hampered the analysis of resistance in some accessions. Two accessions, PI 201237 and PI 640532, demonstrated consistently high levels of resistance to root rot. These two accessions are potential sources of resistance genes that can be incorporated into commercial bell pepper cultivars.

scholarly journals New Sources of Resistance in Winter Squash (Cucurbita moschata) to Phytophthora Crown Rot and Their Relationship to Cultivated Squash

2021 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Gregory Vogel ◽  
Jennifer L. Ikerd ◽  
Mihir K. Mandal ◽  
Michael Mazourek ◽  
...  
Keyword(s):  
South Carolina ◽  
Root Rot ◽  
Rating Scale ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Human Consumption ◽  
Cucurbita Moschata ◽  
Sources Of Resistance ◽  
Plant Introductions ◽  
Crown And Root Rot

Butternut squash (Cucurbita moschata) is an important vegetable crop grown and consumed in most states in the USA. Cucurbita moschata lines and interspecific hybrids between Cucurbita species are also used as rootstocks for grafting watermelon and melon. However, currently most commercially available C. moschata squash varieties are highly susceptible to crown and root rot caused by the oomycete pathogen Phytophthora capsici, especially in the southeastern USA. All available plant introductions (PIs) of C. moschata (319 PIs) were evaluated for resistance to crown rot. Four-week-old plants were inoculated with 104 zoospores from a local South Carolina (SC) isolate of P. capsici. Plants were rated for disease severity three weeks after inoculation using a 0-5 rating scale (0=No symptoms and 5=Plant dead). The majority (87%) of the C. moschata PIs were highly susceptible to crown rot in the first evaluation and were rated as 5. Reevaluation of the promising PIs identified several potential new sources of resistance (e.g. Grif 935, PI 442272, PI 442264, PI 512142, PI 438724, PI 438778, PI 442280). Variability in resistance reaction among plants within a PI was also observed, and not all plants exhibited resistance. Further evaluation of S1 generation from the most resistant plants (rated ≤1) demonstrated that highly resistant plants could be selected from these PIs to develop lines for use in breeding programs. These new sources of resistance can be utilized for developing new crown and root rot resistant rootstocks for watermelon grafting and for developing resistant varieties for human consumption.

scholarly journals Inheritance of Phytophthora Stem Blight Resistance as Compared to Phytophthora Root Rot and Phytophthora Foliar Blight Resistance in Capsicum annuum L.

2005 ◽  
Vol 130 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Ousmane Sy ◽  
Paul W. Bosland ◽  
Robert Steiner
Keyword(s):  
Root Rot ◽  
Single Gene ◽  
Phytophthora Capsici ◽  
Blight Resistance ◽  
Limiting Factor ◽  
Stem Cuttings ◽  
Phytophthora Root Rot ◽  
Stem Blight ◽  
Foliar Blight ◽  
Genetic Mechanisms

The pathogen Phytophthora capsici Leon. is known to be a limiting factor of chile pepper (Capsicum L.) production around the world. The genetics of the resistance is becoming better understood due to the specific nature of the host-pathogen interaction, i.e., all plant organs are subject to infection. It has been shown that phytophthora root rot resistance and phytophthora foliar blight resistance are under different genetic mechanisms. This study aimed at understanding the inheritance of resistance of phytophthora stem blight and to determine whether phytophthora stem blight was the same disease syndrome as phytophthora root rot and phytophthora foliar blight. Stem cuttings of a segregating F2 population and testcross progeny facilitated the ability to screen for two disease syndromes concurrently. When the three disease syndromes were compared separately, the F2 populations fit a 3 resistant (R): 1 susceptible (S) ratio and the testcross progenies fit a 1R:1S ratio. When comparative studies were performed (stem vs. foliar and stem vs. root), the F2 populations fit a 9R/R:3R/S:3S/R:1S/S ratio and the testcross fit a 1R/R:1R/S:1S/R:1S/S ratio. These ratios are consistent of a single gene controlling the resistance of each system. Therefore, phytophthora stem blight, root rot, and foliar blight are three separate disease syndromes.

scholarly journals (252) Inheritance of Phytophthora Stem Blight, Root Rot, and Foliar Blight Resistance in Capsicum

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1047B-1047
Author(s):  
Ousmane Sy ◽  
Paul W. Bosland
Keyword(s):  
Root Rot ◽  
Single Gene ◽  
Phytophthora Capsici ◽  
Limiting Factor ◽  
Stem Cuttings ◽  
Specific Nature ◽  
Stem Blight ◽  
Host Pathogen Interaction ◽  
Foliar Blight ◽  
The World

The oomycete fungus Phytophthora capsici Leon. is known to be a limiting factor of chile pepper (Capsicum spp.) production around the world. The genetics of the resistance is becoming better understood due to the specific nature of the host–pathogen interaction; i.e., all plant organs are subject to infection. This study determined whether stem blight was the same disease syndrome as root rot or foliar blight. Stem cuttings of a segregating F2 population and testcross progeny facilitated the ability to screen for two disease syndromes concurrently. When the three disease syndromes were compared separately, the F2 populations fit a 3R:1S ratio and the testcross progeny fit a 1R:1S ratio. When comparative studies were performed (stem vs. foliar and stem vs. root), the F2 populations fit a 9R/R:3R/S:3S/R:1S/S ratio and the testcross fit a 1R/R:1R/S:1S/R:1S/S ratio. These ratios are consistent of a single gene controlling the resistance of each system. Therefore, Phytophthora stem blight, root rot, and foliar blight are three separate disease syndromes.

Construction of 2 intraspecific linkage maps and identification of resistance QTLs for Phytophthora capsici root-rot and foliar-blight diseases of pepper (Capsicum annuum L.)

Genome ◽  
2005 ◽  
Vol 48 (4) ◽  
pp. 698-711 ◽  
Author(s):  
Ebenezer A Ogundiwin ◽  
Terry F Berke ◽  
Mark Massoudi ◽  
Lowell L Black ◽  
Gordon Huestis ◽  
...  
Keyword(s):  
Root Rot ◽  
Random Amplified Polymorphic Dna ◽  
Phytophthora Capsici ◽  
Fruit Shape ◽  
Linkage Maps ◽  
Morphological Markers ◽  
Linkage Groups ◽  
Resistance Qtls ◽  
Foliar Blight ◽  
Pepper Genome

Two linkage maps of pepper were constructed and used to identify quantitative trait loci (QTLs) conferring resistance to Phytophthora capsici. Inoculations were done with 7 isolates: 3 from Taiwan, 3 from California, and 1 from New Mexico. The first map was constructed from a set of recombinant inbred lines (RILs) of the PSP-11 (susceptible) × PI201234 (resistant) cross; and the second map was from a set of F2 lines of the Joe E. Parker' (susceptible) × 'Criollo de Morelos 334' (resistant) cross. The RIL map covered 1466.1 cM of the pepper genome, and it consisted of 144 markers - 91 amplified fragment length polymorphisms (AFLPs), 34 random amplified polymorphic DNA (RAPDs), 15 simple sequence repeats (SSRs), 1 sequence characterized amplified region (SCAR), and 3 morphological markers - distributed over 17 linkage groups. The morphological markers mapped on this population were erect fruit habit (up), elongated fruit shape (fse), and fasciculate fruit clusters (fa). The F2 map consisted of 113 markers (51 AFLPs, 45 RAPDs, 14 SSRs, and 3 SCARs) distributed in 16 linkage groups, covering a total of 1089.2 cM of the pepper genome. Resistance to both root rot and foliar blight were evaluated in the RIL population using the 3 Taiwan isolates; the remaining isolates were used for the root-rot test only. Sixteen chromosomal regions of the RIL map contained single QTLs or clusters of resistance QTLs that had an effect on root rot and (or) foliar blight, revealing a complex set of genetics involved in resistance to P. capsici. Five QTLs were detected in the F2 map that had an effect on resistance to root rot.Key words: Phytophthora capsici, QTLs, fasciculate, resistance, isolates, pepper, fruit shape.

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