Advances in Allium Breeding and Genetics

A special issue of Horticulturae (ISSN 2311-7524). This special issue belongs to the section "Genetics, Genomics, Breeding, and Biotechnology (G2B2)".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 15276

Special Issue Editors


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Guest Editor
Department of Plant and Environmental Sciences, New Mexico State University, P.O. Box 30003, MSC 3Q, Las Cruces, NM 88003, USA
Interests: onion breeding; plant disease resistance; Fusarium basal rot; Iris yellow spot; onion thrips
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Guest Editor
Department of Horticultural Sciences, Texas A&M University, College Station, Brazos County, TX 77840, USA
Interests: onion breeding; marker-assisted selection; plant disease resistance; pink root rot; bacterial bulb rot

Special Issue Information

Dear Colleagues,

Allium plant species are important worldwide as crop and ornamental plants. They impact our lives on a daily basis. There are many challenges impacting Allium production worldwide. Through breeding and genetics, these challenges can be addressed and overcome.

In this Special Issue, we hope to highlight the research being undertaken to address these challenges using breeding and genetics. We welcome review articles spotlighting the latest research efforts with Alliums and original research papers that highlight the breeding or genetics research your team has conducted with Alliums.

Prof. Dr. Chris S. Cramer
Dr. Subas Malla
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Horticulturae is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Disease resistance breeding
  • Cultivar development
  • Molecular genetics
  • Marker-assisted selection

Published Papers (7 papers)

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Research

14 pages, 1274 KiB  
Article
Onion Plant Size Measurements as Predictors for Onion Bulb Size
by Seyed Shahabeddin Nourbakhsh and Christopher S. Cramer
Horticulturae 2022, 8(8), 682; https://doi.org/10.3390/horticulturae8080682 - 27 Jul 2022
Cited by 3 | Viewed by 3746
Abstract
Onion is a biennial plant that produces a bulb. The larger the onion bulb, the more valuable it becomes. Therefore, it is important to study bulb weight and plant size components affecting it. For this study, four New Mexico State Univ. breeding lines [...] Read more.
Onion is a biennial plant that produces a bulb. The larger the onion bulb, the more valuable it becomes. Therefore, it is important to study bulb weight and plant size components affecting it. For this study, four New Mexico State Univ. breeding lines and two commercial cultivars, ‘Rumba’ and ‘Stockton Early Yellow’, were selected. These breeding lines and cultivars were evaluated for plant height, leaf number and sheath diameter, at five different dates two weeks apart throughout the growing season, and for bulb weight upon harvest. The experiment was designed as a randomized complete block design with three blocks each containing four replications. Plant size components were all positively correlated with each other and with bulb weight with correlation coefficients above 0.50. NMSU breeding lines also exhibited greater average bulb weights than commercial cultivars. Sheath diameter proved to be the best predictor of bulb size, showing strong positive correlations with bulb weight at around 12 weeks after transplanting, and positive correlations are observed as early as 6–8 weeks after transplanting. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
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11 pages, 279 KiB  
Article
Onion Germplasm Possesses Lower Early Season Thrips Numbers
by Seyed Shahabeddin Nourbakhsh and Christopher S. Cramer
Horticulturae 2022, 8(2), 123; https://doi.org/10.3390/horticulturae8020123 - 29 Jan 2022
Cited by 3 | Viewed by 1993
Abstract
Onion is one of the most valuable vegetable crops in the US. Onion thrips were identified as one of the main threats to the US onion industry. An integrated approach, including host plant tolerance, is required. For this study, four New Mexico State [...] Read more.
Onion is one of the most valuable vegetable crops in the US. Onion thrips were identified as one of the main threats to the US onion industry. An integrated approach, including host plant tolerance, is required. For this study, four New Mexico State University breeding lines, along with two thrips-attractive cultivars, were evaluated for their attractiveness to thrips. In addition, this study observed thrips population dynamics throughout the growing season and the relationship between onion plant size and thrips attractiveness. The experiment was designed as a randomized complete block design with three blocks, each containing four replications. Thrips-infested bulbs were used to ensure the presence of thrips and thrips-attractive plants were used to ensure equal thrips distribution throughout the field. Ten plants were randomly selected from each plot and thrips and leaf numbers were counted multiple times through the growing season. Plants of NMSU breeding lines were observed to have fewer thrips, be more tolerant to thrips pressure and produce more leaves and larger bulbs than thrips-attractive entries. Early in the growing season, leaf number was not a determining factor in thrips population dynamics. The larger bulb weights of the breeding lines allowed them to maintain their market value. A delay in thrips population buildup in plants of the breeding lines may result in the critical threshold for spraying for thrips being reached later in these lines. This would potentially allow for fewer pesticide applications by growers, increasing growers’ profits and ensuring a more environmentally friendly approach to plant production. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
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9 pages, 235 KiB  
Article
Genetic Analyses of Resistance to Fusarium Basal Rot in Onion
by Elizabeth Straley, Jen Colcol Marzu and Michael J. Havey
Horticulturae 2021, 7(12), 538; https://doi.org/10.3390/horticulturae7120538 - 02 Dec 2021
Cited by 3 | Viewed by 1908
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
11 pages, 259 KiB  
Article
Screening of USDA Onion Germplasm for Fusarium Basal Rot Resistance
by Subhankar Mandal and Christopher S. Cramer
Horticulturae 2021, 7(7), 174; https://doi.org/10.3390/horticulturae7070174 - 02 Jul 2021
Cited by 3 | Viewed by 2104
Abstract
Fusarium basal rot (FBR) caused by Fusarium oxysporum f. sp. cepae (FOC) is a major threat to onion (Allium cepa L.) production and marketing worldwide. Finding new sources of FBR-resistance to develop synthetic cultivars is a priority for onion breeders. As there [...] Read more.
Fusarium basal rot (FBR) caused by Fusarium oxysporum f. sp. cepae (FOC) is a major threat to onion (Allium cepa L.) production and marketing worldwide. Finding new sources of FBR-resistance to develop synthetic cultivars is a priority for onion breeders. As there are no FBR-resistant short-day onion cultivars, 85 U.S. National Plant Germplasm System plant introduction onion accessions that originated from 23 different countries were screened for their FBR susceptibility. To compare FBR susceptibility of these accessions at their seedling and mature bulb stages, a susceptible check cultivar, NuMex Crimson, a partially resistant check cultivar, Serrana and its selected population, Serrana-sel, were included in the study. The seedling screening was performed after inoculating silica-sand media with a virulent FOC isolate ‘CSC-515’ at 1.0 × 104 macroconidia g−1 of sand. Each entry was evaluated twice in growth chambers, and percent survival was adjusted to the number of seedlings that germinated in the uninoculated trays. Mature bulbs produced in the field were screened by inoculating transversely cut basal plates with potato dextrose agar plugs containing spores of the same isolate at 3.0 × 104 macroconidia mL−1. FBR severity and incidence were then calculated after 20 days of incubation. Significant variation was found among the accessions for FBR-susceptibility (p < 0.001) at both the seedling and the mature bulb stages. Two sets of 18 accessions were identified either for their higher seedling survival or higher mature bulb FBR-resistance compared to the checks. Among them, PI 256326 (‘Baia Periforme’, the originator cultivar of ‘Serrana’) had a higher seedling survival than both the checks, and a lower mature bulb severity than the susceptible check. Another accession, PI 656956 (‘S015’), exhibited higher seedling survival than the susceptible check and a low FBR severity (4.3 on a 1 to 9 scale) and incidence (41.7%). These two accessions, which were known previously for their high intra-population heterogeneity and root or bulb resistance for FBR, respectively, show promise for incorporating FBR-resistance into short-day onion cultivars. The cultivar rankings could vary in future studies with a range of FOC isolates due to a high cultivar × isolate interaction as observed in past studies. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
13 pages, 1591 KiB  
Article
Improving Fusarium Basal Rot Resistance of Onion Cultivars through Artificial Inoculation and Selection of Mature Bulbs
by Subhankar Mandal and Christopher S. Cramer
Horticulturae 2021, 7(7), 168; https://doi.org/10.3390/horticulturae7070168 - 29 Jun 2021
Cited by 3 | Viewed by 2181
Abstract
Fusarium basal rot (FBR) of onion, caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), results in a substantial storage loss of marketable bulbs. Seedling and field screening methods, which were used to generate FBR resistant long-day and intermediate-day onion cultivars, were [...] Read more.
Fusarium basal rot (FBR) of onion, caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), results in a substantial storage loss of marketable bulbs. Seedling and field screening methods, which were used to generate FBR resistant long-day and intermediate-day onion cultivars, were found to be ineffective at increasing FBR resistance in short-day onion cultivars. This study attempted to improve the FBR resistance of seven commercial short-day onion cultivars and two check cultivars when evaluated at their mature bulb stage. Mature bulbs were artificially inoculated with 1 cm diameter potato dextrose agar plugs containing conidia of a virulent FOC isolate, CSC-515, at a concentration of 3 × 104 spore mL−1, after transversely cutting the basal plate tissue. Incubated bulbs, which had few or no FBR symptoms, were selected after 20 d using visual scoring, from 1 (no disease) to 9 (>70% basal plate is infected), and combined in seed production cages to produce the selected generation of a cultivar. Multiple cycles of phenotypic recurrent selection were conducted, and the resultant populations were compared with their respective original populations for FBR severity and incidence, from 2016 to 2019, using the same conidial inoculation method. A variable amount of progress was achieved in reducing FBR severity and incidence in the seven cultivars, with maximum improvement in the most advanced selected populations. FBR development in the advanced selected populations differed between mature bulbs of each entry and was influenced by yearly environmental variation. The progress of FOC infections was slower in resistant bulbs when compared to susceptible bulbs. These results indicated a partial or quantitative resistance against FBR. The partial FBR resistant cultivar populations could be used to develop synthetic short-day FBR resistant cultivars after multi-locational and multi-seasonal field trials. These populations could also be used to study the mechanism(s) of FBR resistance in onion, which has yet to be determined. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
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17 pages, 3513 KiB  
Article
Comparing Visual and Image Analysis Techniques to Quantify Fusarium Basal Rot Severity in Mature Onion Bulbs
by Subhankar Mandal and Christopher S. Cramer
Horticulturae 2021, 7(6), 156; https://doi.org/10.3390/horticulturae7060156 - 19 Jun 2021
Cited by 2 | Viewed by 3929
Abstract
Development of resistant cultivars for Fusarium basal rot (FBR), a fungal disease caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), is a major breeding goal for onion breeding programs around the world. Currently, the selection of FBR-resistant bulbs is based on [...] Read more.
Development of resistant cultivars for Fusarium basal rot (FBR), a fungal disease caused by the soil-borne fungus Fusarium oxysporum f.sp. cepae (FOC), is a major breeding goal for onion breeding programs around the world. Currently, the selection of FBR-resistant bulbs is based on a visual interval or category scale, which is an entirely subjective method. This study aimed to develop an objective approach using digital image analysis to quantify symptom development in the basal plate of dormant bulbs. Digital image analyses were performed after artificially inoculating dormant bulbs of eighty-five United States Department of Agriculture (USDA) Allium cepa accessions with a virulent FOC isolate, ‘CSC-515’. An analysis with confocal microscopy identified bright blue–green autofluorescence from FOC-infected tissue, effectively differentiating diseased from healthy tissue. Visual scoring of the FBR symptom was aided by stereo fluorescence microscopic images captured using a green fluorescence protein dual filter to quantify accurately FBR severity in the basal plate tissue. An automatic stepwise image segmentation method was developed that was relatively more accurate than a visual estimation. This method exhibited comparable reliability and precision to visual scoring, but it tended to underestimate FOC infection. To our best knowledge, this is the first comprehensive study to investigate the potential use of image analysis as a viable alternative to conventional visual scoring for FBR symptom development. This method could be used for developing resistant cultivars for onion breeding programs in the near future. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
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11 pages, 11207 KiB  
Article
Reduced Iris Yellow Spot Symptoms through Selection within Onion Breeding Lines
by Neel Kamal, Seyed Shahabeddin Nourbakhsh and Christopher S. Cramer
Horticulturae 2021, 7(2), 12; https://doi.org/10.3390/horticulturae7020012 - 22 Jan 2021
Cited by 7 | Viewed by 2500
Abstract
Iris yellow spot (IYS) disease in onion (Allium cepa L.) is caused by onion thrips (Thrips tabaci L.) vectored Iris yellow spot virus (IYSV). The absence of cultivars that are resistant/tolerant to thrips and/or IYS is a challenge for onion bulb [...] Read more.
Iris yellow spot (IYS) disease in onion (Allium cepa L.) is caused by onion thrips (Thrips tabaci L.) vectored Iris yellow spot virus (IYSV). The absence of cultivars that are resistant/tolerant to thrips and/or IYS is a challenge for onion bulb and seed production worldwide. To measure selection progress for reduced/delayed IYS symptom expression in onion breeding lines after two selection cycles, selections were performed in 2011 on previously evaluated lines that exhibited a reduced symptom expression after one selection cycle. Selected plants from each line were massed in a cage and the resulted progenies were evaluated in 2013 and 2014 along with their original populations and a susceptible check—’Rumba’. In some comparisons, the selection progress for delayed/reduced IYS symptom expression was observed for some breeding lines. Plants of most selected breeding lines exhibited less disease expression than plants of ‘Rumba’. For some selections, a low disease severity was observed even with a relatively high number of thrips per plant. These results suggest that further improvement might be achievable with additional cycles of selection. Full article
(This article belongs to the Special Issue Advances in Allium Breeding and Genetics)
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