Breeding onion for resistance to Fusarium basal rot: comparison of field selection and artificial inoculation

2020 ◽  
Vol 45 (5) ◽  
pp. 493-498
Author(s):  
Pablo F. Caligiore-Gei ◽  
M. Lucía Ciotti ◽  
Jorge G. Valdez ◽  
Claudio R. Galmarini
Keyword(s):  
Artificial Inoculation ◽  
Basal Rot ◽  
Fusarium Basal Rot

scholarly journals An Artificial Inoculation Method to Select Mature Onion Bulbs Resistant to Fusarium Basal Rot

HortScience ◽  
2020 ◽  
Vol 55 (11) ◽  
pp. 1840-1847
Author(s):  
Subhankar Mandal ◽  
Christopher S. Cramer
Keyword(s):  
Basal Plate ◽  
Artificial Inoculation ◽  
Economic Damage ◽  
Screening Methods ◽  
Field Inoculation ◽  
Inoculation Method ◽  
Short Day ◽  
Onion Bulbs ◽  
Basal Rot ◽  
Fusarium Basal Rot

Fusarium basal rot (FBR) of onion, which is caused by Fusarium oxysporum f.sp. cepae (Hanzawa) Snyder & Hansen (FOC) results in a substantial loss of marketable bulbs worldwide. One of the main reasons for the lack of FBR-resistant short-day cultivars is the unreliable screening methods available for the mature bulb stage when significant economic damage occurs. The objective of this study was to develop an artificial inoculation method with better quantification of inoculum for an effective selection of FBR-resistant mature onion bulbs. Mature bulbs of seven New Mexican short-day onion cultivars, along with susceptible and tolerant controls, were selected and evaluated for FBR resistance using mycelial and conidial inoculation methods, respectively. Transversely cut basal plates of mature bulbs were inoculated artificially with mycelia or conidia (12 × 105 spores/mL in 2014 and 3 × 105 spores/mL in 2015 embedded in potato dextrose agar plug) of a virulent FOC isolate ‘CSC-515’. Mature bulb evaluation using a visual rating scale (1 = no disease; 9 = >70% basal plate infected) revealed a high degree of FBR severity and incidence irrespective of the genetic background of the cultivars, minimizing the chance of disease escape, which is a significant problem in field inoculation. An attempt to inoculate intact basal plates postharvest resulted in minimal disease development, suggesting that mechanical resistance was conferred by the dry outer layer of the basal plate. The high selection pressure conferred by the conidial inoculation method developed in this study can effectively screen FBR-resistant onion bulbs to replace an unreliable field screening. Concentrations of the conidia lower than 3 × 105 spores/mL are recommended to detect subtle genetic differences in FBR resistance among the onion cultivars and their selected population.

scholarly journals Fusarium basal rot: profile of an increasingly important disease in Allium spp.

2021 ◽  
Author(s):  
Dung Le ◽  
Kris Audenaert ◽  
Geert Haesaert
Keyword(s):  
Disease Management ◽  
Cultural Practices ◽  
Current Knowledge ◽  
Management Strategies ◽  
Future Directions ◽  
Basal Rot ◽  
Major Constraint ◽  
Fusarium Basal Rot ◽  
Chemical Pesticides ◽  
Important Disease

AbstractFusarium basal rot (FBR) is a soil-borne disease that affects Allium species worldwide. Although FBR has long been recognized as a major constraint to the production of economically important Allium species, information that could support disease management remains scattered. In this review, the current knowledge on the causal agents, symptomology and epidemiology, impact, and management strategies of FBR is synthesized. We highlight that FPR is associated with different complexes of several Fusarium species, of which Fusarium oxysporum and F. proliferatum are the most prevalent. These pathogenic complexes vary in composition and virulence, depending on sites and hosts, which can be challenging for disease management. Research to improve disease management using chemical pesticides, resistance cultivars, biocontrol agents, and cultural practices has achieved both promising results and limitations. Finally, research needs and future directions are proposed for the development of effective FBR management strategies.

scholarly journals Evaluation of Green Manure Amendments for the Management of Fusarium Basal Rot (Fusarium oxysporumf.sp.cepae) on Shallot

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Assefa Sintayehu ◽  
Seid Ahmed ◽  
Chemeda Fininsa ◽  
P. K. Sakhuja
Keyword(s):  
Green Manure ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Limiting Factors ◽  
Lepidium Sativum ◽  
Ethiopian Mustard ◽  
Basal Rot ◽  
Fusarium Basal Rot ◽  
Manure Amendments

Shallot (Allium cepaL. var.ascalonicum) is the most traditional vegetable crop in Ethiopia. Shallot is susceptible to a number of diseases that reduce yield and quality, among which fusarium basal rot (FBR) caused byFusarium oxysporumf.sp.cepae (Foc)is one of the most important yield limiting factors in Ethiopia. The present study was designed to evaluate the effectiveness ofBrassicacrops for the management of shallot FBR on shallot. The experiments were carried out at Debre Zeit Agricultural Research Center using cabbage (Brassica oleracea), garden cress (Lepidium sativum), Ethiopia mustard (B. carinata), and rapeseed (B. napus). The evaluations were done underin vitroand greenhouse conditions. Underin vitrotest condition it was confirmed that extracts of Ethiopian mustard and rapeseed showed higher inhibition on the growth ofFocpathogen compared to control. Data on seedling emergence, plant height, plant stand, disease incidence, severity, cull bulbs, and bulb weight were collected in greenhouse experiment. The green manure amendments of rapeseed and Ethiopian mustard significantly reduced disease incidence by 21% and 30% and disease severity by 23% and 29%, respectively. However the plant emergency was not significantly different among treatments in greenhouse test. These results indicated that Ethiopian mustard and rapeseed crops have potential as green manure for the management of FBR disease of shallot crop.

scholarly journals Comparing Efficiencies of Two Selection Approaches for Improving Fusarium Basal Rot Resistance in Short-Day Onion after a Single Cycle of Selection

Horticulturae ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 26
Author(s):  
Subhankar Mandal ◽  
Ashish Saxena ◽  
Christopher S. Cramer ◽  
Robert L. Steiner
Keyword(s):  
Environmental Factors ◽  
Random Distribution ◽  
Single Cycle ◽  
Field Screening ◽  
Selection Cycle ◽  
Short Day ◽  
Basal Rot ◽  
Fusarium Basal Rot ◽  
Consistent Method ◽  
Screening Approaches

The development of Fusarium Basal Rot (FBR)-resistant onion cultivars through field and seedling screening approaches faces tremendous challenges due to non-uniform distribution of the disease pathogen and possible multiple mechanisms of host–plant resistance. This study compared the efficiencies of these two methods for increasing FBR resistance of short-day onion after a single selection cycle. Asymptomatic plants or bulbs of seven onion cultivars were selected using a seedling screen performed in a growth chamber or a field screening of mature bulbs. Original and selected populations were evaluated for their responses to FBR stress thereafter employing the same two methods used for screening. The field screening of mature bulbs was found unreliable in both selection and evaluation, likely due to a non-random distribution of the FBR pathogen and variable environmental factors present in the field. The seedling screening successfully increased FBR resistance in the selected cultivar populations revealed by a seedling evaluation. From the results, it is recommended to use a consistent method for both screening and evaluation to make the most selection progress.

scholarly journals Trait Heritability Estimates of an Open-pollinated Onion Population

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 812A-812
Author(s):  
Christopher S. Cramer*
Keyword(s):  
Selection Response ◽  
Planting Date ◽  
Realized Heritability ◽  
Outer Scale ◽  
Narrow Sense Heritability ◽  
Scale Thickness ◽  
Basal Rot ◽  
Family Analysis ◽  
Fusarium Basal Rot ◽  
Heritability Estimates

Heritability estimates of bolting percentage (BP), pink root (PR) and Fusarium basal rot (FBR) incidences, and percentage of single centered (PSC) bulbs were calculated for an intermediate-day, open-pollinated onion population using selection response and half-sib (HS) family analyses. BP was determined by counting the number of seedstalks per plot when the population was seeded at an earlier planting date to induce bolting. PR and FBR incidences were determined by rating 30 bulbs/plot for the severity of PR and FBR, and calculated an incidence rate from the number of infected bulbs out of 30 rated. The PSC bulbs was determined by cutting transversely 30 bulbs at the vertical center of the bulb and looking for the presence of a single growing point or multiple growing points within 1.3 cm from the center of the bulb. Families were also evaluated for bulb quality that consisted of shape, size, maturity, firmness, number of scale layers, and dry outer scale thickness, adherence, retention, and color. Families were selected based upon an index that equally weighted BP, PR and FBR incidences, PSC bulbs, and bulb quality. No progress was made for BP even though the narrow sense heritability (h2) estimate was 0.51. PR and FBR incidence was reduced by 18% and 12%, respectively, and realized heritability (RH) estimates of 0.65 and 0.60, respectively, were calculated. h2 estimates calculated through HS family analysis was 0.46 and 0.37, respectively, for these two traits. Very little progress was made for the PSC bulbs and this was reflected in a RH estimate of 0.17. However, the h2 estimate was 0.71, suggesting that progress should be possible.

scholarly journals Yield and Dry Weight of Dehydrator Onions after Uprooting at Maturity and Delaying Harvest

HortScience ◽  
1999 ◽  
Vol 34 (6) ◽  
pp. 1068-1070 ◽  
Author(s):  
Arthur D. Wall ◽  
Joe N. Corgan
Keyword(s):  
Treatment Effects ◽  
Dry Weight ◽  
Yield Losses ◽  
Time Intervals ◽  
Basal Rot ◽  
Fusarium Basal Rot ◽  
Dry Climates

In dry climates, onions usually have the roots undercut at maturity before harvest. In a 2-year study, dehydrator onions were uprooted at maturity to simulate undercutting, and harvest was delayed for several time intervals. Treatment effects on fresh and dry yield, the number of bulbs per plot, bulb fresh and dry weights, and percent dry weight of bulbs were measured. Plots were considered mature when 80% of the tops had fallen. Delaying harvest 15 days after maturity without uprooting did not reduce yield significantly. Yield and both bulb weight and percent dry weight tended to decline when harvest was delayed >15 days after maturity, especially if plants were uprooted. This suggests that undercutting of onions should not be performed until just prior to harvest and that harvest should not be delayed >15 days past maturity. Yield losses in delayed harvest treatments were attributed primarily to Fusarium basal rot.

scholarly journals Genetic Analyses of Resistance to Fusarium Basal Rot in Onion

Horticulturae ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 538
Author(s):  
Elizabeth Straley ◽  
Jen Colcol Marzu ◽  
Michael J. Havey
Keyword(s):  
Combining Ability ◽  
Specific Combining Ability ◽  
Chromosome 4 ◽  
Male Sterile ◽  
Basal Rot ◽  
Percentage Survival ◽  
Fusarium Basal Rot ◽  
High Heritability ◽  
Serious Disease ◽  
Genomic Regions

Fusarium basal rot (FBR) is a serious disease of onion (Allium cepa). We identified sources of FBR resistance, assessed efficacy of selection for increased resistance, and investigated its genetic control. Onion accessions were evaluated for FBR resistance, and percentage survival ranged from 0% to 78%. Survivors were intercrossed, and progenies from one cycle of selection showed increased survival by 18% to 52%. Selections were crossed to male-sterile lines, and hybrids showed specific combining ability for FBR resistance. Segregating families were produced, and quantitative trait loci (QTLs) were identified on chromosomes 2 and 4 conditioning FBR resistance. A second QTL on chromosome 4 was identified that decreased FBR resistance. Plants from families with different genotypes across the 1.5 logarithm of odds (LOD) regions on chromosomes 2 and 4 were self-pollinated, and resulting families were evaluated for FBR survival. Genomic regions on chromosomes 2 and 4 associated with resistance were validated at p = 0.05 and 0.10, respectively. The region on chromosome 4 associated with increased susceptibility was validated at p = 0.05. These results are in agreement with previous studies reporting high heritability and specific combining ability for FBR resistance and should be useful for selection of FBR-resistant onion.

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