Tolerance to Virulence Phenotypes of Phytophthora capsici in Pasilla Pepper Cultivars

Phytophthora capsici is the most important limiting factor in the production of chile pepper in Mexico. This pathogen presents virulence phenotypes capable of infecting diverse cultivars of this crop. The search and development of resistance in chile pepper is an excellent alternative for the management of P. capsici. The objective of this work was to evaluate the response of four pasilla pepper cultivars to infection with five virulence phenotypes of P. capsici. Pasilla pepper landraces PAS-1, PAS-2, PAS-3, and PAS-4 were inoculated with P. capsici isolates MX-1, MX-2, MX-7, MX-8, and MX-10. Two experiments were conducted under greenhouse conditions from April through June 2017 and April through June 2018. ‘California Wonder’ was included as a susceptible control, and uninoculated plants were included as a negative control. In each experiment, groups of six 56-day-old plants from each pepper cultivar were inoculated with each virulence phenotype. Disease severity was evaluated 20 days after inoculation using an individual plant severity scale. All pepper cultivars were classified as resistant = R, moderately resistant (MR), tolerant (T), moderately tolerant (MT), or susceptible (S), according to the frequency of resistant plants (severity 0–1). ‘California Wonder’ and ‘PAS-4’ were susceptible to all five virulence phenotypes. The rest had different responses to the virulence phenotypes, but ‘PAS-2’ and ‘PAS-3’ were susceptible to only one of the five virulence phenotypes. Pasilla peppers with low severity exhibited a slow rate of infection, which is a mechanism we have called “slow wilting.” The pasilla pepper cultivars PAS-1, PAS-2, and PAS-3 could be used in plant breeding programs as sources of genetic tolerance and moderate resistance against P. capsici.

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Evaluation of a Diverse, Worldwide Collection of Wild, Cultivated, and Landrace Pepper (Capsicum annuum) for Resistance to Phytophthora Fruit Rot, Genetic Diversity, and Population Structure

Phytopathology ◽

10.1094/phyto-02-14-0031-r ◽

2015 ◽

Vol 105 (1) ◽

pp. 110-118 ◽

Cited By ~ 10

Author(s):

R. P. Naegele ◽

A. J. Tomlinson ◽

M. K. Hausbeck

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Phytophthora Capsici ◽

The United States ◽

Fruit Rot ◽

Sources Of Resistance ◽

Plant Introductions ◽

Genetic Clusters ◽

Commercial Breeding ◽

Moderately Resistant

Pepper is the third most important solanaceous crop in the United States and fourth most important worldwide. To identify sources of resistance for commercial breeding, 170 pepper genotypes from five continents and 45 countries were evaluated for Phytophthora fruit rot resistance using two isolates of Phytophthora capsici. Genetic diversity and population structure were assessed on a subset of 157 genotypes using 23 polymorphic simple sequence repeats. Partial resistance and isolate-specific interactions were identified in the population at both 3 and 5 days postinoculation (dpi). Plant introductions (PIs) 640833 and 566811 were the most resistant lines evaluated at 5 dpi to isolates 12889 and OP97, with mean lesion areas less than Criollo de Morelos. Genetic diversity was moderate (0.44) in the population. The program STRUCTURE inferred four genetic clusters with moderate to very great differentiation among clusters. Most lines evaluated were susceptible or moderately susceptible at 5 dpi, and no lines evaluated were completely resistant to Phytophthora fruit rot. Significant population structure was detected when pepper varieties were grouped by predefined categories of disease resistance, continent, and country of origin. Moderately resistant or resistant PIs to both isolates of P. capsici at 5 dpi were in genetic clusters one and two.

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Resistance to Meloidogyne arenaria in Advanced Generation Breeding Lines of Peanut1

Peanut Science ◽

10.3146/pnut.22.1.0013 ◽

1995 ◽

Vol 22 (1) ◽

pp. 59-61 ◽

Cited By ~ 15

Author(s):

J. L. Starr ◽

C. E. Simpson ◽

T. A. Lee

Keyword(s):

Field Tests ◽

Recurrent Parent ◽

Meloidogyne Arenaria ◽

Root Knot Nematode ◽

Nematode Reproduction ◽

Breeding Lines ◽

Nematode Population Density ◽

Arachis Batizocoi ◽

Moderate Resistance ◽

Moderately Resistant

Abstract Levels of resistance to the root-knot nematode Meloidogyne arenaria in F2 individuals from the second, third, and fourth backcross (BC) generations were compared in seven separate tests to that of the root-knot nematode-resistant peanut germplasm line TxAG-7. Resistance of TxAG-7 was derived from the wild species Arachis batizocoi, A. cardenasii, and A. diogoi. Recurrent susceptible parents were Florunner and Tamnut 74 for the all backcrosses, Tamspan 90 for BC3 and BC4, and NC 7 and VC-1 for BC4. Resistance in these tests was defined as an inhibition of nematode reproduction relative to that of the susceptible recurrent parent. Numerous individuals with a level of resistance similar to that of TxAG-7 were identified from each backcross generation. In three field tests, the resistant BC2 genotype TP-223 supported a lower final nematode population density than did its susceptible recurrent parent Florunner. When rooted cuttings from selected BC4F2 individuals were retested to confirm the original resistance class, ratings were unchanged for those originally identified as resistant or susceptible. Of nine individuals originally identified as having moderate resistance (2.5 to 12.5% of the eggs/g roots as the susceptible recurrent parent), one was identified as susceptible, one as moderately resistant, and seven as resistant (<2.5% of the eggs/g roots) upon retest. These data are evidence that this source of resistance is readily recoverable from advanced back-cross generations.

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Host suitability of different wheat lines to Pratylenchus thornei under naturally infested field conditions in Turkey

Nematology ◽

10.1163/15685411-00003235 ◽

2019 ◽

Vol 21 (6) ◽

pp. 557-571 ◽

Cited By ~ 1

Author(s):

Abdelfattah A. Dababat ◽

Fouad Mokrini ◽

Salah-Eddine Laasli ◽

Şenol Yildiz ◽

Gül Erginbas-Orakci ◽

...

Keyword(s):

Field Experiments ◽

Field Conditions ◽

Nematode Reproduction ◽

Pratylenchus Thornei ◽

Wide Range ◽

Infested Field ◽

Breeding Programmes ◽

Moderate Resistance ◽

Wheat Lines ◽

Moderately Resistant

Summary The root-lesion nematode, Pratylenchus thornei, attacks a wide range of crops and causes significant reductions in global grain production. Breeding programmes are currently restricted to using parents with moderate resistance to P. thornei as cereal cultivars with complete resistance are yet to be identified. This study evaluated 484 of CIMMYT’s spring wheat accessions for resistance to P. thornei of which 56 lines were pre-identified as resistant under controlled growth room conditions. These lines were further evaluated for their resistance and tolerance reactions under field conditions, where 14 accessions maintained their resistance and 16 were moderately resistant against P. thornei. Four lines gave excellent resistant and tolerance reactions to P. thornei. The relationship between the nematode reproduction factor (Pf/Pi) and wheat grain yield in field experiments fits a linear regression model. These findings could be useful for improving P. thornei resistance in wheat.

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Asexual Reproduction of Phytophthora capsici as Affected by Extracts from Agricultural and Nonagricultural Soils

Phytopathology ◽

10.1094/phyto-97-7-0873 ◽

2007 ◽

Vol 97 (7) ◽

pp. 873-878 ◽

Cited By ~ 2

Author(s):

S. Sanogo

Keyword(s):

New Mexico ◽

Chemical Composition ◽

Discriminant Analysis ◽

Phytophthora Capsici ◽

Organic Matter Content ◽

Discriminant Functions ◽

Chile Pepper ◽

Soil Extracts ◽

Significant Difference ◽

History Of

Formation of sporangia and zoospores in species of Phytophthora is known to be influenced by soil microbial and chemical composition. In Phytophthora capsici, the study of the relationship of soil chemical composition to production of sporangia and zoospores has been limited. P. capsici is a soilborne pathogen of a wide array of vegetable crops, including chile pepper (Capsicum annuum) in New Mexico. Production of sporangia and zoospores by P. capsici was evaluated in extracts of soils from three different environments in New Mexico: (i) agricultural environments with a long history of chile pepper cropping and occurrence of P. capsici (CP), (ii) agricultural environments with no history of chile pepper cropping and no occurrence of P. capsici (Non-CP), and (iii) nonagricultural environments consisting of forests and rangelands (Non-Ag). There was a significant difference in production of P. capsici asexual propagules, expressed as natural log (number of sporangia × number of zoospores), among the three environments (P = 0.0298). Production of propagules was 9 to 13% greater in Non-Ag than in CP or Non-CP environments. Stepwise multiple discriminant analysis and canonical discriminant analysis identified the edaphic variables Na, pH, P, organic matter content, and asexual propagule production as contributing the most to the separation of the three environments. Two significant (P < 0.0001) canonical discriminant functions were derived with the first function, accounting for ≈75% of the explained variance. Based on the two discriminant functions, ≈93, 86, and 89% of observations in CP, Non-CP, and Non-Ag environments, respectively, were classified correctly. Soils from agricultural and nonagricultural environments differentially influence production of sporangia and zoospores in P. capsici, and soil samples could be effectively classified into agricultural and nonagricultural environments based on soil chemical properties and the production of asexual propagules by P. capsici in soil extracts.

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Field screening of common jute (Corchorus olitorius) varieties against major pests in Eastern Terai region of Nepal

International Journal of Agricultural Invention ◽

10.46492/ijai/2019.4.2.2 ◽

2019 ◽

Vol 4 (02) ◽

pp. 130-134

Author(s):

Govinda Prasad Timsina ◽

Sujan Karki

Keyword(s):

Production Capacity ◽

Fibre Production ◽

Economic Damage ◽

Corchorus Olitorius ◽

Field Screening ◽

Major Pest ◽

Moderate Resistance ◽

Moderately Resistant ◽

Spilarctia Obliqua ◽

Varietal Preference

Field screening of eleven most popular jute varieties belonging to Corchorus olitorius species was done against the major pests in the farm of Jute Research Programm, Itahari, Sunsari, Nepal during 2017 and 2018. Different species of pests belonging to insects, mites and nematodes were found feeding on jute. Among them, jute Semilooper (Anomis sabulifera Guen.), Bihar hairy caterpillar (Spilarctia obliqua Wlk.), yellow mite (Polyphagotarson emuslatus Banks), are causing economic damage to the jute crop. Eleven jute varieties were selected to conduct varietal preference and tested against major pest of jute in field condition. Among the eleven varieties JRO-524 was found to be moderately resistant against the Semilooper (A. sabulifera) and Bihar hairy caterpillar (S. oblique) but least susceptible to yellow mites. Likewise, the variety KEN-DS-058, KEN-DS-066, BJRI-1965 and BJRI-1968 showed highly susceptible to major pest Semilooper (A. sabulifera), Bihar hairy caterpillar (S. oblique) and yellow mites. The variety BRD-SRB-061, YA-41, O-4, KEN-BL-130, Itahari-2 showed moderate resistance to Semilooper (A. sabulifera), Bihar hairy caterpillar (S. oblique) but moderately susceptible to yellow mites. Further, the fibre production capacity of the varieties under different pest’s pressure was found relatively higher in variety JRO-524 followed by YA-41, BRD-SRB-061, KEN-BL-130 and O-4 respectively. The relatively higher yield recorded under varying pest levels over two consecutive seasons is an indicative of greater field tolerance of olitorius jute varieties.

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Resistance to Fludioxonil in Botrytis cinerea Isolates from Blackberry and Strawberry

Phytopathology ◽

10.1094/phyto-11-13-0308-r ◽

2014 ◽

Vol 104 (7) ◽

pp. 724-732 ◽

Cited By ~ 36

Author(s):

Xingpeng Li ◽

Dolores Fernández-Ortuño ◽

Anja Grabke ◽

Guido Schnabel

Keyword(s):

South Carolina ◽

Botrytis Cinerea ◽

Resistance Mechanism ◽

Gray Mold ◽

Development Of Resistance ◽

Atp Binding Cassette Transporter ◽

Glycerol Synthesis ◽

Increased Sensitivity ◽

Moderately Resistant ◽

Gene Alterations

Site-specific fungicides, including the phenylpyrrole fludioxonil, are frequently used for gray mold control but are at risk for the development of resistance. In this study, field isolates that were low-resistant (LR) and moderately resistant (MR) to fludioxonil from blackberry and strawberry fields of North Carolina, South Carolina, and Virginia were characterized. Genes involved in osmoregulation, including bcsak1, BcOS4, bos5, and BRRG-1, were cloned and sequenced to detect potential target gene alterations; however, none were found. A previously described mutation (R632I) in transcription factor Mrr1, which is known to increase the expression of ATP-binding cassette transporter AtrB, was found in MR but not in sensitive (S) or LR isolates. Expression of atrB in MR isolates was ≈200-fold increased compared with an S isolate; however, 30- to 100-fold overexpression was also detected in LR isolates. Both MR isolates exhibited increased sensitivity to salt stress in the form of mycelial growth inhibition at 4% NaCl, indicating a disruption of osmoregulatory processes in those strains. However, the glycerol content was indistinguishable between S, LR, and MR isolates with and without exposure to fludioxonil, suggesting that the glycerol synthesis pathway may not be a part of the resistance mechanism in LR or MR strains. An investigation into the origin of LR and MR isolates from blackberry revealed two insertions in the mrr1 gene consistent with those found in the Botrytis clade group S. The emergence of strains overexpressing atrB in European and now in North American strawberry fields underscores the importance of this resistance mechanism for development of resistance to fludioxonil in Botrytis cinerea.

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Evaluation of Eggplant Rootstocks and Pepper Varieties for Potential Resistance to Isolates of Phytophthora capsici from Michigan and New York

Plant Disease ◽

10.1094/pdis-06-12-0562-re ◽

2013 ◽

Vol 97 (8) ◽

pp. 1037-1041 ◽

Cited By ~ 7

Author(s):

J. M. Foster ◽

R. P. Naegele ◽

M. K. Hausbeck

Keyword(s):

New York ◽

Root Rot ◽

Phytophthora Capsici ◽

Economic Importance ◽

Soilborne Pathogen ◽

Breeding Lines ◽

Wide Range ◽

Moderate Resistance ◽

Fungicide Insensitivity ◽

Pepper Cultivar

Phytophthora capsici is a soilborne pathogen of major economic importance in pepper, and of less importance in tomato and eggplant production. As soil fumigation becomes more expensive and limited, and fungicide insensitivity of P. capsici isolates becomes more prevalent, grafting is quickly becoming an industry-favored method to control soilborne diseases. Greenhouse experiments were performed to evaluate an eggplant cultivar (Classic), two eggplant lines (EG195, EG203), a pepper line (CM334), and three pepper cultivars (Paladin, Camelot, and Red Knight) for root rot resistance to 14 P. capsici isolates. The isolates showed various degrees of virulence between pepper and eggplant in both experiments. Both eggplant and one pepper lines showed moderate resistance to the most virulent isolates tested in experiment one. The partially resistant pepper cultivar, Paladin, was significantly more susceptible than CM334 and the eggplant lines, but was still resistant to most isolates. In the second experiment, the eggplant cultivar Classic and the susceptible pepper cultivar Red Knight were both susceptible to most isolates tested, while EG203 and EG195 were resistant to most isolates. The two eggplant breeding lines, EG195 and EG203, showed moderate resistance to all isolates tested in both experiments. This is the first reported evaluation of eggplant resistance to P. capsici. Further research is warranted to test eggplant lines EG195 and EG203 for resistance to a wide range of soilborne pests and to evaluate their usefulness as P. capsici–resistant rootstocks for peppers, tomatoes, and eggplants.

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Additional East European Pyrus Germplasm with Resistance to Pear Psylla Nymphal Feeding

HortScience ◽

10.21273/hortsci.27.5.412 ◽

1992 ◽

Vol 27 (5) ◽

pp. 412-413 ◽

Cited By ~ 10

Author(s):

R.L. Bell

Keyword(s):

Eastern Europe ◽

Host Resistance ◽

East European ◽

Reduced Frequency ◽

Pear Psylla ◽

Early Instar ◽

Susceptible Control ◽

High Degree ◽

Moderately Resistant

Eight cultivars and wild seedlings of pear (Pyrus spp.) from Eastern Europe were evaluated for resistance to feeding by early instar pear psylla [Cacopsylla pyricola (Foerster)] in a 24-hour assay. All were compared to a susceptible control, `Bartlett' (P. communis L.), and to a moderately resistant control, NY10352 (P. communis × P. ussuriensis Maxim. BC hybrid). Three P. communis cultivars, Bartjarka (PI 483391), Lucele (PI 483402), and Kajzerka (PI 506387), and a wild seedling (PI 506381) of undetermined species, exhibited a high degree of host resistance, measured as reduced frequency of feeding and increased either mortality or movement off of the plants.

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Peningkatan Pertumbuhan Tanaman Cabai dan Pengendalian Busuk Phytophthora melalui Biopriming Benih dengan Rizobakteri Asal Pertanaman Cabai Jawa Timur

Jurnal Hortikultura Indonesia ◽

10.29244/jhi.8.3.171-182 ◽

2017 ◽

Vol 8 (3) ◽

pp. 171 ◽

Cited By ~ 2

Author(s):

Aulia Zakia ◽

Satriyas Ilyas ◽

Candra Budiman ◽

Syamsuddin , ◽

Dyah Manohara

Keyword(s):

Plant Growth ◽

Seed Treatment ◽

Block Design ◽

Phytophthora Capsici ◽

Positive Control ◽

Negative Control ◽

Phytophthora Blight ◽

Blight Disease ◽

And Control ◽

East West

ABSTRACT The objectives of this study was to evaluate biopriming of chili seed with rhizobacteria to improve plant growth and control Phytophthora blight disease in a greenhouse. This experiment used three isolates of rhizobacteria, i.e. E1, E3C2 and F2B1, and isolate Phytophthora capsici (Cb6) isolated from the production center of chili in East Jawa. Laris variety from PT. East West was used in this experiment. This experiment used randomized block design with one factor, i.e. 11 levels of seed treatment (E1 rhizobacteria, E3C2 rhizobacteria, F2B1 rhizobacteria, E1+E3C2 rhizobacteria, E1+F2B1 rhizobacteria, E1+E3C2+F2B1 rhizobacteria, seed soaking in water, without soaking, metalaxyl, positive control and negative control). The result showed that seed treatment with combination of E1+F2B1 isolates when grown in nursery, significantly increased the height and number of leaves in chilli. Besides, seed treatment with F2B1 isolate and combination of E1+F2B1 isolates after transplanting were capable to improve plant growth and control Phytophthora blight disease in greenhouse.Keywords: greenhouse, isolate rhizobacteria, Phytophthora capsici ABSTRAK Tujuan penelitian ini ialah mengevaluasi perlakuan biopriming benih cabai dengan rizobakteri dalam meningkatkan pertumbuhan bibit dan mengendalikan kejadian busuk Phytophthora di rumah kaca. Perlakuan biopriming benih dengan rizobakteri menggunakan tiga isolat rizobakteri E1, E3C2 dan F2B1 dan isolat Phytophthora capsici Cb6 hasil eksplorasi pertanaman cabai Jawa Timur. Benih yang digunakan dalam percobaan merupakan benih varietas Laris produksi PT. East West. Percobaan menggunakan rancangan acak kelompok satu faktor, masing-masing perlakuan diulang empat kali, dengan 11 taraf perlakuan, antara lain R0+ (kontrol positif, benih direndam dalam PDB tanpa perlakuan rizobakteri dengan inokulasi P. capsici), R0- (kontrol negatif, benih direndam dalam PDB tanpa perlakuan rizobakteri dan tanpa inokulasi P. capsici), R1 (perlakuan benih dengan isolat E1), R2 (isolat E3C2), R3 (isolat F2B1), R4 (kombinasi isolat E1+E3C2), R5 (kombinasi isolat E1+F2B1), R6 (kombinasi isolat E1+E3C2+F2B1), R0RA (benih direndam dalam air 24 jam), R0TR (benih tanpa rendam), R0M (benih direndam dalam metalaksil). Tanah inokulum P. capsici diberikan 28 hari setelah pindah-tanam di sekitar pangkal batang tanaman cabai di bawah permukaan tanah. Hasil percobaan menunjukkan, perlakuan dengan kombinasi isolat E1+F2B1 saat persemaian di rumah kaca nyata meningkatkan tinggi dan jumlah daun tanaman cabai. Perlakuan benih dengan isolat F2B1 maupun kombinasi isolat E1+F2B1 setelah pindah-tanam di rumah kaca memiliki kemampuan meningkatkan pertumbuhan tanaman serta mengendalikan penyakit busuk Phytophthora. Kata kunci: isolat rizobakteri, Phytophthora capsici, rumah kaca

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IDENTIFICATION OF COWPEA GENOTYPES RESISTANT TO FUSARIUM WILT1

Revista Caatinga ◽

10.1590/1983-21252021v34n423rc ◽

2021 ◽

Vol 34 (4) ◽

pp. 957-964

Author(s):

RISONEIDE DE CÁSSIA ZEFERINO SILVA ◽

ANTHONY CARLOS DA SILVA ◽

REZANIO MARTINS CARVALHO ◽

ANTONIO FÉLIX DA COSTA ◽

ALESSANDRO NICOLI ◽

...

Keyword(s):

Fusarium Wilt ◽

Conidial Suspension ◽

The North ◽

Randomized Design ◽

Susceptible Control ◽

Bean Yield ◽

Descriptive Scale ◽

The University ◽

Moderately Resistant ◽

Resistant Genotypes

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

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