QTL Mapping for Gummy Stem Blight Resistance in Watermelon (Citrullus spp.)

Watermelon (Citrulluslanatus) is an economically important fruit crop worldwide. Gummy stem blight (GSB) is one of the most damaging diseases encountered during watermelon cultivation. In the present study, we identified quantitative trait loci (QTLs) associated with GSB resistance in an F2 population derived from a cross between maternal-susceptible line ‘920533’ (C. lanatus) and the paternal-resistant line ‘PI 189225’ (C. amarus). The resistance of 178 F2 plants was assessed by two different evaluation methods, including leaf lesion (LL) and stem blight (SB). To analyze the QTLs associated with GSB resistance, a linkage map was constructed covering a total genetic distance of 1070.2 cM. QTL analysis detected three QTLs associated with GSB resistance on chromosome 8 and 6. Among them, two QTLs, qLL8.1 and qSB8.1 on chromosome 8 identified as major QTLs, explaining 10.5 and 10.0% of the phenotypic variations localizing at same area and sharing the same top markers for both LL and SB traits, respectively. A minor QTL, qSB6.1, explains 9.7% of phenotypic variations detected on chromosome 6 only for the SB trait. High-throughput markers were developed and validated for the selection of resistant QTLs using watermelon accessions, and commercial cultivars. Four potential candidate genes were predicted associated with GSB resistance based on the physical location of flanking markers on chromosome 8. These findings will be helpful for the development of watermelon cultivars resistant to GSB.

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Gummy Stem Blight Resistance in Melon: Inheritance Pattern and Development of Molecular Markers

International Journal of Molecular Sciences ◽

10.3390/ijms19102914 ◽

2018 ◽

Vol 19 (10) ◽

pp. 2914 ◽

Cited By ~ 5

Author(s):

Md Zahid Hassan ◽

Md Abdur Rahim ◽

Sathishkumar Natarajan ◽

Arif Hasan Khan Robin ◽

Hoy-Taek Kim ◽

...

Keyword(s):

Molecular Markers ◽

Recessive Gene ◽

Chromosome 9 ◽

Stem Blight ◽

Gummy Stem Blight ◽

F2 Population ◽

First Intron ◽

Frameshift Deletion ◽

Cucumis Melo L ◽

Selection Of

Gummy stem blight (GSB) causes enormous losses to melon (Cucumis melo L.) production worldwide. We aimed to develop useful molecular markers linked to GSB resistance. In this study, 168 F2 plants were obtained from the F1 population of a cross between the GSB-susceptible ‘Cornell ZPPM 339’ and the GSB-resistant ‘PI482399’ lines. A 3:1 ratio of susceptible and resistant genotypes was observed in the F2 population, indicating control by a single recessive gene. Nucleotide-binding site leucine-rich repeat (NBS-LRR) genes confer resistance against insects and diseases in cucurbits including melon. We cloned and sequenced the TIR-NBS-LRR-type resistance gene MELO3C022157, located on melon chromosome 9, from resistant and susceptible lines. Sequence analysis revealed deletions in the first intron, a 2-bp frameshift deletion from the second exon and a 7-bp insertion in the 4th exon of the resistant line. We developed two insertion/deletion (InDel) markers, GSB9-kh-1 and GSB9-kh-2, which were found in the first intron of MELO3C022157 linked to GSB resistance. We validated these markers with the F2 population and inbred lines. These InDels may be used to facilitate marker-assisted selection of GSB resistance in melon. However, functional analysis of overexpressing and/or knock-down mutants is needed to confirm the frameshift mutation.

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Selection of melon genotypes with resistance to Didymella bryoniae using a diallel approach

Acta Scientiarum Agronomy ◽

10.4025/actasciagron.v41i1.42600 ◽

2019 ◽

Vol 41 (1) ◽

pp. 42600

Author(s):

Lucas Da Silva Santos ◽

Guilherme Matos Martins Diniz ◽

Rafaelle Fazzi Gomes ◽

Edgard Henrique Costa Silva ◽

Alysson Jalles da Silva ◽

...

Keyword(s):

Rating Scale ◽

Didymella Bryoniae ◽

Reciprocal Effect ◽

Stem Blight ◽

Gummy Stem Blight ◽

Group I ◽

Diallel Mating Design ◽

Resistant Lines ◽

Selection Of ◽

Partial Diallel

The development of melon lines resistant to gummy stem blight (GSB) is an important strategy for decreasing losses caused by this disease. Thus, selecting the best parents for such a goal is essential. We evaluated the general (GCA) and specific (SCA) combining abilities of lines and accessions to guide the selection of the most promising parents to develop GSB-resistant lines. Six genotypes representing two groups (group I - susceptible: group II - resistant) were crossed in a partial diallel mating design. The genotypes were evaluated for disease expression using a rating scale from 0 (resistant) to 4 (susceptible). Estimates of GCA were negative and significant for the accessions PI 420145 and PI 482398, which can be suggested for crosses aimed at obtaining melon lines resistant to GSB. There is a reciprocal effect for the resistance of melon genotypes to Didymella bryoniae, especially when PI 482398, PI 420145, and PI 140471 are crossed with JAB-20. Such results indicate that maternal effects may be involved in the resistance to gummy stem blight.

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QTL associated with gummy stem blight resistance in watermelon

Theoretical and Applied Genetics ◽

10.1007/s00122-020-03715-9 ◽

2020 ◽

Author(s):

Winnie Gimode ◽

Kan Bao ◽

Zhangjun Fei ◽

Cecilia McGregor

Keyword(s):

Disease Resistance ◽

Phenotypic Variation ◽

Citrullus Lanatus ◽

Genetic Resistance ◽

Blight Resistance ◽

Yield Losses ◽

Stem Blight ◽

Gummy Stem Blight ◽

Cost Of Disease ◽

Selection Of

Abstract Key message We identified QTLs associated with gummy stem blight resistance in an interspecific F2:3Citrullus population and developed marker assays for selection of the loci in watermelon. Abstract Gummy stem blight (GSB), caused by three Stagonosporopsis spp., is a devastating fungal disease of watermelon (Citrullus lanatus) and other cucurbits that can lead to severe yield losses. Currently, no commercial cultivars with genetic resistance to GSB in the field have been reported. Utilizing GSB-resistant cultivars would reduce yield losses, decrease the high cost of disease control, and diminish hazards resulting from frequent fungicide application. The objective of this study was to identify quantitative trait loci (QTLs) associated with GSB resistance in an F2:3 interspecific Citrullus mapping population (N = 178), derived from a cross between Crimson Sweet (C. lanatus) and GSB-resistant PI 482276 (C. amarus). The population was phenotyped by inoculating seedlings with Stagonosporopsis citrulli 12178A in the greenhouse in two separate experiments, each with three replications. We identified three QTLs (ClGSB3.1, ClGSB5.1 and ClGSB7.1) associated with GSB resistance, explaining between 6.4 and 21.1% of the phenotypic variation. The genes underlying ClGSB5.1 includes an NBS-LRR gene (ClCG05G019540) previously identified as a candidate gene for GSB resistance in watermelon. Locus ClGSB7.1 accounted for the highest phenotypic variation and harbors twenty-two candidate genes associated with disease resistance. Among them is ClCG07G013230, encoding an Avr9/Cf-9 rapidly elicited disease resistance protein, which contains a non-synonymous point mutation in the DUF761 domain that was significantly associated with GSB resistance. High throughput markers were developed for selection of ClGSB5.1 and ClGSB7.1. Our findings will facilitate the use of molecular markers for efficient introgression of the resistance loci and development of GSB-resistant watermelon cultivars.

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Identification and Molecular Mapping of a Gummy Stem Blight Resistance Gene in Wild Watermelon (Citrullus amarus) Germplasm PI 189225

Plant Disease ◽

10.1094/pdis-04-19-0753-re ◽

2020 ◽

Vol 104 (1) ◽

pp. 16-24 ◽

Cited By ~ 2

Author(s):

Runsheng Ren ◽

Jinhua Xu ◽

Man Zhang ◽

Guang Liu ◽

Xiefeng Yao ◽

...

Keyword(s):

Resistance Gene ◽

Molecular Mapping ◽

Gene Annotation ◽

Snp Markers ◽

Chromosome 8 ◽

Disease Resistance Gene ◽

Resistance Locus ◽

Annotation Database ◽

Stem Blight ◽

Gummy Stem Blight

Gummy stem blight (GSB), caused by Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae), is a destructive foliar disease of watermelon in areas with hot and humid climates. The wild watermelon germplasm PI 189225 is a known source of resistance to GSB. The identification and use of molecular markers linked to resistance genes in the wild-type germplasm will speed up the introgression of GSB resistance into new watermelon varieties. An F2 segregating population was obtained from a cross between the resistant wild watermelon genotype PI 189225 and the susceptible genotype K3. The F2-derived F3 families were inoculated with a single isolate of S. cucurbitacearum (JS002) from Jiangsu Academy of Agricultural Sciences. The results of the genetic analysis demonstrated that GSB resistance in PI 189225 was controlled by a major quantitative trait locus (QTL), temporarily designated Qgsb8.1. Based on the results of bulk sergeant analysis and sequencing, one associated region spanning 5.7 Mb (10,358,659 to 16,101,517) on chromosome 8 was identified as responsible for the resistance to GSB using the Δ(single-nucleotide polymorphism [SNP]-index) method. The result of a QTL linkage analysis with Kompetitive allele-specific PCR (KASP) SNP markers further mapped the GSB resistance locus between the SNP markers KASP_JS9383 and KASP_JS9168 in a region of 571.27 kb on chromosome 8. According to the watermelon gene annotation database, the region contains approximately 19 annotated genes and, of these 19 genes, 2 are disease resistance gene analogs: Cla001017 (coiled-coil nucleotide-binding site leucine-rich repeat resistance protein) and Cla001019 (pathogenesis related). Reverse-transcription quantitative PCR demonstrated that the expression of the two genes changed following S. cucurbitacearum infection, suggesting that they play important roles in GSB resistance in watermelon. This result will facilitate fine mapping and cloning of the Qgsb8.1 locus, and the linked markers will further provide a useful tool for marker-assisted selection of this locus in watermelon breeding programs.

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Molecular Tagging of Gummy Stem Blight Resistance in Watermelon

HortScience ◽

10.21273/hortsci.33.3.472e ◽

1998 ◽

Vol 33 (3) ◽

pp. 472e-472

Author(s):

Young-Seok Kwon ◽

Young Hyun Om ◽

Leigh Hawkins ◽

Fenny Dane

Keyword(s):

Plant Introduction ◽

Aflp Markers ◽

Blight Resistance ◽

Didymella Bryoniae ◽

Molecular Tagging ◽

Stem Blight ◽

Gummy Stem Blight ◽

Blight Disease ◽

Fungus Disease ◽

Selection Of

The fungus Didymella bryoniae causes gummy stem blight (foliar phase) and black rot (fruit phase) in cucurbits. As resistance to other diseases have been incorporated into cucurbits, losses due to gummy stem blight have increased. Populations derived from crosses between a cultivated watermelon (SS-4), susceptible to the fungus Didymella bryoniae and resistant plant introduction accessions (PI 189225 and PI 272778) are used to detect molecular markers linked to gummy stem blight disease resistance. Genomic DNA was purified from primary leaves of watermelon seedlings before seedlings were inoculated with a spore suspension of the fungus. Disease severity was rated 4 days after inoculation. DNA bulked from resistant or susceptible BC seedlings was amplified to detect AFLP markers. Linkages between gummy stem blight resistance and AFLP markers were identified and should facilitate evaluation and selection of watermelon populations segregating for gummy stem blight resistance.

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Factors Promoting Pycnidia Production of Didymella bryoniae, the Causal of Gummy Stem Blight in Cucurbits

Egyptian Journal of Phytopathology ◽

10.21608/ejp.2017.89736 ◽

2017 ◽

Vol 45 (1) ◽

pp. 173-187

Author(s):

Abdel-Fattah El-Wakil ◽

Amal Khalil ◽

Ibrahim El -Abbasi

Keyword(s):

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight

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Temporal and spatial dynamics of watermelon gummy stem blight epidemics

European Journal of Plant Pathology ◽

10.1007/s10658-010-9674-1 ◽

2010 ◽

Vol 128 (4) ◽

pp. 473-482 ◽

Cited By ~ 5

Author(s):

Adalberto C. Café-Filho ◽

Gil R. Santos ◽

Francisco F. Laranjeira

Keyword(s):

Spatial Dynamics ◽

Stem Blight ◽

Gummy Stem Blight ◽

Temporal And Spatial

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Boscalid Insensitivity Documented in Didymella bryoniae Isolated from Watermelon in Florida and North Carolina

Plant Health Progress ◽

10.1094/php-2012-0518-01-br ◽

2012 ◽

Vol 13 (1) ◽

pp. 42

Author(s):

Katherine L. Stevenson ◽

Anthony P. Keinath ◽

Anna Thomas ◽

David B. Langston ◽

Pamela D. Roberts ◽

...

Keyword(s):

North Carolina ◽

South Carolina ◽

High Frequency ◽

In Vitro Assays ◽

Didymella Bryoniae ◽

Triazole Fungicides ◽

Stem Blight ◽

Gummy Stem Blight ◽

Commercial Mixture

The fungicide Pristine, a commercial mixture of pyraclostrobin and boscalid, has been used widely on watermelon and other cucurbits to control gummy stem blight, caused by the fungus Didymella bryoniae. Since 2007, isolates of D. bryoniae insensitive to boscalid have been found in Georgia, Indiana, and South Carolina. Most isolates of D. bryoniae obtained in 2009 and 2010 from diseased watermelon leaves collected in several counties in Florida and North Carolina were found to be insensitive to boscalid using in vitro assays. Gummy stem blight would not be effectively managed with Pristine in any of the counties where samples were collected due to the high frequency of insensitivity to boscalid. Fortunately growers can instead use several triazole fungicides registered for use on cucurbits since 2009. Accepted for publication 30 March 2012. Published 18 May 2012.

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