scholarly journals Genotypic and Phenotypic Variation among Pepper Accessions Resistant to Phytophthora capsici

HortScience ◽  
2011 ◽  
Vol 46 (9) ◽  
pp. 1235-1240 ◽  
Author(s):  
Cecilia McGregor ◽  
Vickie Waters ◽  
Savithri Nambeesan ◽  
Dan MacLean ◽  
Byron L. Candole ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Phytophthora Capsici ◽  
Fruit Size ◽  
Phytophthora Blight ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Phytophthora Root Rot ◽  
Ssr Loci ◽  
Fruit Size And Shape ◽  
Pericarp Thickness

Developing high levels of resistance to Phytophthora blight (Phytophthora capsici Leonian) of pepper (Capsicum annuum L.) is a goal of many pepper breeding programs. Genetic diversity and plant characteristics were evaluated on 21 pepper accessions previously identified as having high levels of Phytophthora root rot resistance. Accessions were evaluated for plant height, fruit size and shape, pericarp thickness, and pungency. Accessions varied widely from very unadapted material to those with more obvious breeding potential. Genetic diversity among the accessions was estimated using 22 simple sequence repeat (SSR) loci. Phytophthora capsici resistant accessions were identified that were not closely related to previously described sources of resistance. This information will allow breeders and researchers to further identify and incorporate novel sources of resistance to P. capsici into breeding programs. Accessions PI 201237 and PI 640532 appear to have the most potential for introgressing P. capcisi resistance into bell pepper.

scholarly journals Potential Sources of Resistance in U.S. Cucumis melo PIs to Crown Rot Caused by Phytophthora capsici

HortScience ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 164-170 ◽  
Author(s):  
Ryan S. Donahoo ◽  
William W. Turechek ◽  
Judy A. Thies ◽  
Chandrasekar S. Kousik
Keyword(s):  
Cucumis Melo ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Fruit Rot ◽  
Broad Host Range ◽  
Post Inoculation ◽  
Vegetable Crops ◽  
Phytophthora Blight ◽  
Sources Of Resistance ◽  
Breeding Programs

Phytophthora capsici is an aggressive pathogen that is distributed worldwide with a broad host range infecting solanaceous, fabaceous, and cucurbitaceous crops. Over the past two decades, increased incidence of Phytophthora blight, particularly in eastern states, has threatened production of many vegetable crops. Cucumis melo L. (honeydew and muskmelon), although especially susceptible to fruit rot, is also highly susceptible to crown rot. Currently, little is known about host resistance to P. capsici in C. melo. To assess crown rot resistance in C. melo seedlings, 308 U.S. PIs, and two commercial cultivars (Athena and Dinero) were grown under greenhouse conditions. Seedlings with three to four true leaves were inoculated with a five-isolate zoospore suspension (1 × 104 zoospores per seedling) at the crown and monitored for 6 weeks. All the susceptible control plants of Athena died within 7 days post-inoculation. The majority of the PIs (281 of 308) were highly susceptible to crown rot and succumbed to the disease rapidly and had less than 20% of the plants survive. Several PIs (PI 181748, PI 182964, and PI 273438) succumbed to crown rot earlier than the susceptible melon cultivars. Eighty-seven PIs selected on the basis of the first screen were re-evaluated and of these PIs, 44 were less susceptible than cultivars Athena and Dinero. Twenty-five of the 87 PIs were evaluated again and of these six PI, greater than 80% of the plants survived in the two evaluations. Disease development was significantly slower on these PIs compared with the susceptible checks. High levels of resistance in S1 plants of PI 420180, PI 176936, and PI 176940 were observed, which suggests that development of resistant germplasm for use in breeding programs can be accomplished. Further screening and careful selection within each of these PIs can provide a framework for the development of resistant germplasm for use in breeding programs.

scholarly journals 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

2015 ◽  
Vol 105 (1) ◽  
pp. 110-118 ◽  
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.

The proportion of individual lucerne plants resistant to Phytophthora medicaginis and Colletotrichum trifolii in Australian cultivars

1998 ◽  
Vol 38 (1) ◽  
pp. 41 ◽  
Author(s):  
J. M. Mackie ◽  
J. A. G. Irwin
Keyword(s):  
Root Rot ◽  
Crown Rot ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Phytophthora Root Rot ◽  
Colletotrichum Trifolii ◽  
Eastern Australia

Summary. Phytophthora root rot (Phytophthora medicaginis) and colletotrichum crown rot (Colletotrichum trifolii) are the 2 most serious pathogens of lucerne in eastern Australia. Work reported in this paper shows that in glasshouse tests of the 11 most commonly grown Australian lucerne cultivars, the proportion of individual plants with resistance to both pathogens ranges from 0 (Hunter River and Aurora) through to a maximum of 19.8% (Sequel HR). Within 9 of the cultivars, the proportion of individual plants resistant to the 2 pathogens was <7%. Since these 2 diseases are known to cause serious losses in eastern Australia, the results indicate further improvement in lucerne production can be obtained by increasing the proportion of individual plants in a cultivar resistant to both pathogens. This would be best achieved by identifying dominant sources of resistance and incorporating this into on-going lucerne breeding programs.

scholarly journals Performance and Tolerance to Phytophthora Blight of Bell Pepper Varieties

2013 ◽  
Vol 23 (3) ◽  
pp. 382-390 ◽  
Author(s):  
Amara R. Dunn ◽  
Lindsay E. Wyatt ◽  
Michael Mazourek ◽  
Stephen Reiners ◽  
Christine D. Smart
Keyword(s):  
New York ◽  
Phytophthora Capsici ◽  
Fruit Size ◽  
Bell Pepper ◽  
Plant Structure ◽  
Phytophthora Blight ◽  
Marketable Yield ◽  
Breeding Lines ◽  
History Of ◽  
Low Incidence

In 2011, total marketable yield, fruit size, and number of lobes; fruit discoloration due to silvering; and plant structure were compared among eight commercial green bell pepper (Capsicum annuum) varieties and four breeding lines at three field sites in central New York. Tolerance to phytophthora blight (Phytophthora capsici) was also assessed at one of these sites. No wilting or plant death due to phytophthora blight was observed on the four breeding lines. ‘Paladin’, ‘Intruder’, and ‘Aristotle’ had the highest levels of tolerance to phytophthora blight, among the commercial varieties and maintained their yields in the presence of disease. In the absence of phytophthora blight, yields from these three varieties were comparable to susceptible varieties, but fruit tended to be smaller, and incidence of silvering was high in ‘Paladin’ and ‘Intruder’. Less silvering was observed on ‘Aristotle’ fruit. Total marketable yields from the breeding lines and percent of fruit with four lobes was comparable to the commercial varieties, and some breeding lines also had a low incidence of silvering, but fruit were smaller and set later in the season. Overall, this study suggests that ‘Paladin’, ‘Intruder’, and ‘Aristotle’ will yield well in fields with a history of severe phytophthora blight, but new large-fruited varieties with low incidence of silvering and good tolerance to phytophthora blight are needed.

scholarly journals Characterizing Sources of Resistance to Phytophthora Blight of Pepper Caused by Phytophthora capsici in North Carolina

2019 ◽  
Vol 20 (2) ◽  
pp. 112-119
Author(s):  
Camilo H. Parada-Rojas ◽  
Lina M. Quesada-Ocampo
Keyword(s):  
North Carolina ◽  
Phytophthora Capsici ◽  
The United States ◽  
Field Trials ◽  
Fruit Rot ◽  
Phytophthora Blight ◽  
Sources Of Resistance ◽  
Crown Root ◽  
Different Levels ◽  
Important Disease

Phytophthora blight, caused by Phytophthora capsici, is an important disease of peppers in the United States and worldwide. P. capsici causes crown, root, and fruit rot as well as foliar lesions in peppers. Field trials were conducted in 2015 and 2016 to evaluate 32 commercial and experimental pepper cultivars against a mixed-isolate inoculum in North Carolina. Cultivars Martha-R and Meeting were classified as highly resistant to P. capsici, and Paladin was classified as resistant. Intermediate resistance to P. capsici in the field was observed with Fabuloso, Revolution, Vanguard, Archimedes, Aristotle, Ebano-R, and Declaration. Greenhouse experiments were conducted to determine the response of 48 pepper cultivars when inoculated individually with two isolates from North Carolina and an isolate from Michigan. Isolates exhibited different levels of virulence in pepper cultivars screened for resistance. Landraces CM334 and Fidel as well as the cultivars Martha-R, Meeting, and Intruder were categorized as highly resistant or resistant to the three isolates tested. Overall, highly resistant cultivars tended to respond similarly to field mix inoculations and greenhouse single isolate inoculations.

scholarly journals Phenotypic, Genetic, and Epigenetic Variation among Diverse Sweet Cherry Gene Pools

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 680
Author(s):  
Evangelia V. Avramidou ◽  
Theodoros Moysiadis ◽  
Ioannis Ganopoulos ◽  
Michail Michailidis ◽  
Christos Kissoudis ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sweet Cherry ◽  
Allelic Variation ◽  
Sugar Content ◽  
Fruit Size ◽  
Mantel Test ◽  
Phenotypic Traits ◽  
Gene Pools ◽  
Epigenetic Diversity ◽  
Fruit Size And Shape

Sweet cherry germplasm contains a high variety of phenotypes which are associated with fruit size and shape as well as sugar content, etc. High phenotypic variation can be a result of genetic or epigenetic diversity that may interact through time. Recent studies have provided evidence that besides allelic variation, epiallelic variation can establish new heritable phenotypes. Herein we conducted a genetic and an epigenetic study (using amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP) markers, respectively), accompanied by phenotypic traits correlation analysis in sweet cherry gene pools. The mean genetic diversity was greater than the epigenetic diversity (hgen = 0.193; hepi = 0.185), while no significant relationship was found between genetic and epigenetic distance according to a Mantel test. Furthermore, according to correlation analyses our results provided evidence that epigenetic diversity in predefined populations of sweet cherry had a stronger impact on phenotypic traits than their rich genetic diversity.

scholarly journals Resistance to Phytophthora Fruit Rot of Watermelon Caused by Phytophthora capsici in U.S. Plant Introductions

HortScience ◽  
2012 ◽  
Vol 47 (12) ◽  
pp. 1682-1689 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Jennifer L. Ikerd ◽  
Patrick Wechter ◽  
Howard Harrison ◽  
Amnon Levi
Keyword(s):  
Citrullus Lanatus ◽  
Phytophthora Capsici ◽  
Fruit Rot ◽  
Preliminary Evaluation ◽  
Yield Losses ◽  
Mature Fruit ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Plant Introductions ◽  
Agar Plug

Phytophthora fruit rot, caused by Phytophthora capsici, is prevalent in most watermelon-producing regions of southeastern United States and is known to cause pre- and post-harvest yield losses. A non-wound inoculation technique was developed to evaluate detached mature fruit belonging to U.S. watermelon PIs for resistance to fruit rot caused by P. capsici. Mature fruit were harvested and placed on wire shelves in a walk-in humid chamber [greater than 95% relative humidity (RH), temperature 26 ± 2 °C] and inoculated with a 7-mm agar plug from an actively growing colony of P. capsici. Twenty-four PIs that exhibited resistance in a preliminary evaluation of 205 PIs belonging to the watermelon core collection in 2009 were grown in the field and greenhouse in 2010 and 2011 and evaluated in the walk-in humid chamber. Fruit rot development was rapid on fruit of susceptible controls ‘Black Diamond’, ‘Sugar Baby’, and PI 536464. Several accessions including PI 560020, PI 306782, PI 186489, and PI 595203 (all Citrullus lanatus var. lanatus) were highly resistant to fruit rot. One C. colocynthis (PI 388770) and a C. lanatus var. citroides PI (PI 189225) also showed fruit rot resistance. Fruit from PIs that were resistant also had significantly lower amounts of P. capsici DNA/gram of fruit tissue compared with the susceptible commercial cultivars Sugar Baby and Black Diamond. The sources of resistance to Phytophthora fruit rot identified in this study may prove useful in watermelon breeding programs aimed at enhancing disease resistance.

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.

Genetic diversity analysis among selected short duration chickpeacultivars and breeding lines based on STMS markers.

2016 ◽  
Author(s):  
Syeda Asma Koinain ◽  
V S Hegde ◽  
C . Bharadwaj
Keyword(s):  
Genetic Diversity ◽  
Polymorphic Information Content ◽  
Similarity Index ◽  
Breeding Programs ◽  
Breeding Lines ◽  
Upgma Cluster Analysis ◽  
Ssr Loci ◽  
Clustering Pattern ◽  
Selection Of ◽  
Stms Markers

Genetic diversity among 30 chickpea genotypes was evaluated using simple sequence repeat (SSR) molecular markers. The studies using Sequence Tagged Microsatellite Site (STMS) markers markers revealed that among the primers used across the genotypes produced a total of 35 alleles representing 21 SSR loci with frequencies ranging from one to two (mean 1.66) alleles per locus. Polymorphic Information Content (PIC) ranged from 0.098 to 0.500 (CAM0443, CAM0446). These primers might be an effective and useful tool to determine the genetic differences among chickpea genotypes and to study the phylogenetic relationships. Polymorphic percentage was 96.42. Hierarchical neighbour-joining UPGMA cluster analysis based on simple matching similarity matrix resolved the 30 genotypes into seven clusters. Based on STMS markers highest similarity index 0.850 was observed between BGD 72 and Annigeri-1whereas BGD 9920 and ICC 92944 showed the lowest similarity index 0.214 between them. The STMS clustering pattern indicated the presence of wide genetic diversity between the genotypes. Overall, the study ascertained that SSRs provide powerful marker tools in revealing genetic diversity and relationships in chickpeas, thereby proving useful for selection of parents in breeding programs and also for DNA fingerprinting for identification of cultivars.

scholarly journals Genetic and phenotypic analyses reveal major quantitative loci associated to fruit size and shape traits in a non-flat peach collection (P. persica L. Batsch)

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Marco Cirilli ◽  
Irina Baccichet ◽  
Remo Chiozzotto ◽  
Cristian Silvestri ◽  
Laura Rossini ◽  
...  
Keyword(s):  
Linkage Mapping ◽  
Phenotypic Variability ◽  
Fruit Size ◽  
Chromosome 6 ◽  
Breeding Programs ◽  
Major Locus ◽  
Size And Shape ◽  
Peach Breeding ◽  
Genetic Level ◽  
Fruit Size And Shape

AbstractFruit size and shape are critical agronomical and pomological attributes and prime targets in peach breeding programs. Apart from the flat peach type, a Mendelian trait well-characterized at the genetic level, ample diversity of fruit size and shapes is present across peach germplasms. Nevertheless, knowledge of the underlying genomic loci remains limited. In this work, fruit size and shape were assessed in a collection of non-flat peach accessions and selections, under controlled fruit load conditions. The architecture of these traits was then dissected by combining association and linkage mapping, revealing a major locus on the proximal end of chromosome 6 (qSHL/Fs6.1) explaining a large proportion of phenotypic variability for longitudinal shape and also affecting fruit size. A second major locus for fruit longitudinal shape (qSHL5.1), probably also affecting fruit size, was found co-localizing at locus G, suggesting pleiotropic effects of peach/nectarine traits. An additional QTL for fruit longitudinal shape (qSHL6.2) was identified in the distal end of chromosome 6 in a cross with an ornamental double-flower peach and co-localized with the Di2 locus, controlling flower morphology. Besides assisting breeding activities, knowledge of loci controlling fruit size and shape paves the way for more in-depth studies aimed at the identification of underlying genetic variant(s).

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