Inheritance of Resistance to Powdery Mildew Race 2 in Citrullus lanatus var. lanatus

Information on the mode of inheritance of powdery mildew resistance in watermelon is important for designing a breeding strategy for the development of new cultivars. Resistance in the watermelon accession PI 270545 was investigated by generation means analysis by crossing it with susceptible PI 267677. The analyses showed involvement of two genes, a recessive resistance gene, pmr-1, and a dominant gene for moderate resistance, Pmr-2. Resistance to powdery mildew in the leaf had a large dominance effect and a heritability of 71%. The additive-dominance model was inadequate in explaining variation in leaf resistance as revealed by the joint scaling test. However, nonallelic interactions could not be detected by the nonweighted six-parameter scaling test. For stem resistance, the additive-dominance model was adequate, and inheritance was controlled mainly by additive effects. A high narrow-sense heritability of 79% suggested that selection for stem resistance in early generations would be effective.

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078 Mapping of the Citrullus Genome using Populations Segregating for Fusarium Wilt Resistance

HortScience ◽

10.21273/hortsci.34.3.454e ◽

1999 ◽

Vol 34 (3) ◽

pp. 454E-454

Author(s):

Leigh K. Hawkins ◽

Fenny Dane ◽

Thomas L. Kubisiak ◽

Billy Rhodes

Keyword(s):

Fusarium Wilt ◽

Citrullus Lanatus ◽

Random Amplified Polymorphic Dna ◽

Dominant Gene ◽

Wilt Resistance ◽

Length Polymorphisms ◽

Amplified Fragment Length Polymorphisms ◽

Race 2 ◽

Serious Disease ◽

Simple Sequence

Fusarium wilt, caused by the soilborne fungus Fusarium oxysporum f.sp. niveum (FON), is a serious disease of the watermelon (Citrullus lanatus). Three races of this pathogen (races 0, 1, and 2) have been identified based on differential pathogenicity assays. Most commercially available cultivars are resistant to races 0 and 1. Inheritance for resistance to these races is thought to be controlled by a single dominant gene. No cultivars are resistant to race 2 and resistance is thought to be a quantitative trait. F2 lines derived from a cross between the Fusarium-resistant Citrullus lanatus PI296341, and the Fusarium-susceptible watermelon cultivar `New Hampshire Midget' were used to generate a RAPD-based map of the Citrullus genome. F2:3 families were assayed in the greenhouse for resistance to races 1 and 2. Those families that were either highly resistant or highly susceptible were used in identifying markers linked to Fusarium wilt resistance. A preliminary map of the Citrullus genome based on random amplified polymorphic DNA (RAPD) markers has been expanded with the inclusion of simple sequence repeats (SSRs), amplified fragment length polymorphisms (AFLPs), and isozymes.

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Inheritance of Resistance to Bacterial Blight in 21 Cultivars of Rice

Phytopathology ◽

10.1094/phyto.2003.93.2.147 ◽

2003 ◽

Vol 93 (2) ◽

pp. 147-152 ◽

Cited By ~ 67

Author(s):

K. S. Lee ◽

S. Rasabandith ◽

E. R. Angeles ◽

G. S. Khush

Keyword(s):

Bacterial Blight ◽

Oryza Sativa L ◽

Dominant Gene ◽

Recessive Gene ◽

Inheritance Of Resistance ◽

Race 1 ◽

Group 2 ◽

Race 2 ◽

Moderate Resistance ◽

Group 1

Genetic analysis for resistance to bacterial blight (Xanthomonas oryzae pv. oryzae) of 21 rice (Oryza sativa L.) cultivars was carried out. These cultivars were divided into two groups based on their reactions to Philippine races of bacterial blight. Cultivars of group 1 were resistant to race 1 and those of group 2 were susceptible to race 1 but resistant to race 2. All the cultivars were crossed with TN1, which is susceptible to all the Philippine races of X. oryzae pv. oryzae. F1 and F2 populations of hybrids of group 1 cultivars were evaluated using race 1 and F1 and F2 populations of hybrids of group 2 cultivars were evaluated using race 2. All the cultivars showed monogenic inheritance of resistance. Allelic relationships of the genes were investigated by crossing these cultivars with different testers having single genes for resistance. Three cultivars have Xa4, another three have xa5, one has xa8, two have Xa3, eight have Xa10, and one has Xa4 as well as Xa10. Three cultivars have new, as yet undescribed, genes. Nep Bha Bong To has a new recessive gene for moderate resistance to races 1, 2, and 3 and resistance to race 5. This gene is designated xa26(t). Arai Raj has a dominant gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as Xa27(t). Lota Sail has a recessive gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as xa28(t).

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CmPMRl and CmPMrs Were Responsible for Resistance to Powdery Mildew Caused by Podosphaera Xanthii Race 1 in Melon

10.21203/rs.3.rs-223835/v1 ◽

2021 ◽

Author(s):

Haonan Cui ◽

Chao Fan ◽

Zhuo Ding ◽

Xuezheng Wang ◽

Lili Tang ◽

...

Keyword(s):

Powdery Mildew ◽

Candidate Gene ◽

Cucumis Melo ◽

Dominant Gene ◽

Recessive Gene ◽

Cellular Membrane ◽

Epistatic Effect ◽

Marker Assisted Breeding ◽

Stem Resistance ◽

Race 1

Abstract Cucumis melo L. is an economically important crop, the production of which is threatened by the prevalence of melon powdery mildew (PM) infections. We herein utilized the MR-1 (P1; resistant to PM) and M4-7 (P2; susceptible to PM) accessions to assess the heritability of PM (race 1) resistance in these melon plants. PM resistance in MR-1 leaves was linked to a dominant gene (CmPMRl), whereas stem resistance was under the control of a recessive gene (CmPMrs), with the dominant gene having an epistatic effect on the recessive gene. The CmPMRl gene was mapped to a 50 Kb interval on chromosome 12, while CmPMrs was mapped to an 89 Kb interval on chromosome 10. The CmPMRl candidate gene MELO3C002441 and the CmPMrs candidate gene MELO3C012438 were identified through sequence alignment, functional annotation, and expression pattern analyses of all genes within these respective intervals. MELO3C002441 and MELO3C012438 were both localized to the cellular membrane and were contained conserved NPR gene-like and MLO domains, respectively, which were linked to PM resistance. In summary, we identified patterns of PM resistance in the disease-resistant MR-1 melon cultivar, and conducted finally-mapping to identify two putative genes linked to resistance. Our results offer new genetic resources and markers guide the future molecular marker-assisted breeding of PM-resistant melon.

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Evaluation of U.S. Plant Introductions of Watermelon for Resistance to Powdery Mildew

HortScience ◽

10.21273/hortsci.40.1.154 ◽

2005 ◽

Vol 40 (1) ◽

pp. 154-156 ◽

Cited By ~ 6

Author(s):

Claude E. Thomas ◽

Amnon Levi ◽

Ellis Caniglia

Keyword(s):

Powdery Mildew ◽

Citrullus Lanatus ◽

Sphaerotheca Fuliginea ◽

Test Results ◽

Plant Introductions ◽

Weighted Averages ◽

True Leaf ◽

Intermediate Resistance ◽

Growth Room ◽

Race 2

Two hundred sixty-six Citrullus lanatus (Thumb.) Matsum. & Nakai accessions (Plant Introductions and named cultivars) were tested against a race 2 Sphaerotheca fuliginea (Schlechtend.: Fr.) Pollacci isolate to evaluate for resistance to powdery mildew disease. Growth room-grown seedlings were artificially inoculated with conidia from watermelon host leaves at 2-day intervals from the appearance of the first true leaf until test results data were taken, when the second true leaf was fully expanded. Plants were evaluated on a 1 to 9 scale of increasing disease severity. Disease indices (DIs) were calculated as weighted averages for each entry. All genotypes with resistant plants (powdery mildew rating 1 to 3) were reevaluated in a replicated test of 3 replications of 10 plants each. Disease indices were again calculated. Twenty-two plant introductions (PIs) and one named variety displayed intermediate resistance to powdery mildew in the replicated test with DIs ranging from 5.0 to 6.0.

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UPDATE ON POWDERY MILDEW RESISTANCE SCREENING IN WATERMELON

HortScience ◽

10.21273/hortsci.40.3.872c ◽

2005 ◽

Vol 40 (3) ◽

pp. 872c-872

Author(s):

Angela R. Davis ◽

Todd C. Wehner ◽

Amnon Levi ◽

Stephen R. King

Keyword(s):

United States ◽

South Carolina ◽

Powdery Mildew ◽

Resistance Genes ◽

Citrullus Lanatus ◽

Germplasm Collection ◽

The United States ◽

The Past ◽

Race 1 ◽

Race 2

Powdery mildew has been reported on Citrullus lanatus in Africa and Europe for the past 9 years, and in the United States for the past 6 years. During this time, it has occurred in the main watermelon production areas in the U.S. and has been documented in nine states (South Carolina, Georgia, Florida, Oklahoma, Texas, Maryland, New York, Arizona, and California). This is of great concern to the watermelon industry since powdery mildew is difficult to control and can have a severe impact on yield and fruit quality due to loss of photosynthetic area and sunscald. Finding resistant C. lanatus germplasm is needed for the development of commercial varieties containing this resistance. This report summarized the status of an ongoing project to screen the entire USDA–ARS C. lanatus germplasm collection. Currently, the collection is being screened for race 1 and race 2 Podosphaera xanthii (syn. Sphaerotheca fuliginea auct. p.p.), the causal agent of powdery mildew in C. lanatus in the United States. Resistance genes appear to exist for both races and the genes conferring resistance to race 1 appear to be different than race 2 resistance genes. Allelism tests are currently in process to determine the number of resistance genes present.

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RESISTANCE OF WATERMELON (CITRULLUS LANATUS VAR. CITROIDES) GERMPLASM FOR RESISTANCE TO ROOT-KNOT NEMATODES

HortScience ◽

10.21273/hortsci.41.3.520a ◽

2006 ◽

Vol 41 (3) ◽

pp. 520A-520

Author(s):

J. A. Thies ◽

A. Levi

Keyword(s):

Citrullus Lanatus ◽

Nematode Resistance ◽

Root Knot Nematode ◽

Sources Of Resistance ◽

Root Knot Nematodes ◽

Nematode Reproduction ◽

Plant Introductions ◽

Race 1 ◽

Race 2 ◽

Moderate Resistance

Root-knot nematodes (Meloidogyne incognita, M. arenaria, and M. javanica) cause severe damage to watermelon and resistance has not been identified in any watermelon cultivar. In greenhouse tests, we evaluated 265 U.S. plant introductions (PIs) for nematode resistance (based on root galling and nematode reproduction), and identified 22 PIs of Citrullus lanatus var. citroides as moderately resistant to M. arenaria race 1. In subsequent tests, these 22 PIs exhibited low to moderate resistance to M. incognita race 3 and M. arenaria race 2. Three watermelon (C. lanatus var. lanatus) cultivars (Charleston Gray, Crimson Sweet, and Dixie Lee), three C. colocynthis PIs, and four C. lanatus var. citroides PIs, all previously shown to be susceptible to M. arenaria race 1, were susceptible to M. incognita race 3 and M. arenaria race 2. The C. lanatus var. citroides PIs that are most resistant to both M. incognita and M. arenaria should be useful sources of resistance for developing root-knot nematode resistant watermelon cultivars.

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Implications of Mating Behavior in Watermelon Breeding

HortScience ◽

10.21273/hortsci.48.8.960 ◽

2013 ◽

Vol 48 (8) ◽

pp. 960-964 ◽

Cited By ~ 3

Author(s):

Rakesh Kumar ◽

Mahendra Dia ◽

Todd C. Wehner

Keyword(s):

Mating Behavior ◽

Citrullus Lanatus ◽

Block Design ◽

Dominant Gene ◽

Breeding Strategy ◽

Outcrossing Rate ◽

Genetic Variances ◽

Cross Pollination ◽

Self Pollination ◽

Randomized Complete Block Design

Understanding the natural mating behavior (self- or cross-pollination) in watermelon is important to the design of a suitable breeding strategy. The objective of this study was to measure the rate of self- and cross-pollination in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] using the dominant gene Sp (Spotted leaves and fruit) as a marker. The experiment consisted of two studies and was a split plot in a randomized complete block design with 3 years (2009 to 2011) and four locations (Clinton, Kinston, Oxford, Lewiston, NC). For the intercrossing study, whole plots were the two spacings (1.2 × 0.3 m and 1.2 × 0.6 m) with four replications in 2010. For the inbreeding study, whole plots were two equidistant spacings (3 × 3 m and 6 × 6 m) with four replications in 2009 to 2011. Cultivars Allsweet and Mickylee were subplots within each whole plot. In the inbreeding study, spacing and year had a significant effect on the rate of self-pollination, which was moderate (47% and 54%, respectively) when watermelon plants were trained in a spiral and spaced 3 × 3 m or 6 × 6 m apart. Spacing and cultivar did not have a significant effect on cross-pollination in the intercrossing study. Closely spaced watermelon plants (1.2 × 0.3 m and 1.2 × 0.6 m) had low natural outcrossing rate (31% and 35%, respectively) and was not adequate to intercross families. However, breeders should consider the amount of self-pollination in watermelon to calculate the estimates of component of genetic variances.

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Inheritance of Resistance to Powdery Mildew Race 1W in Watermelon

Phytopathology ◽

10.1094/phyto-02-15-0048-r ◽

2015 ◽

Vol 105 (11) ◽

pp. 1446-1457 ◽

Cited By ~ 5

Author(s):

Yariv Ben-Naim ◽

Yigal Cohen

Keyword(s):

Powdery Mildew ◽

Citrullus Lanatus ◽

Dominant Gene ◽

Inheritance Of Resistance ◽

Resistance Level ◽

Leaf Stage ◽

Cotyledon Stage ◽

Resistant Accession ◽

High Level ◽

Dominant Genes

Powdery mildew caused by Podosphaera xanthii is a major disease of watermelon in Israel. In this study, 291 accessions of Citrullus spp. were evaluated for resistance against P. xanthii race 1W. Only eight accessions exhibited high level of resistance. Inheritance of resistance against P. xanthii race 1W was studied by crossing three resistant accession of Citrullus lanatus var. citroides BIU 119, PI 189225, or PI 482312 with the susceptible cultivar ‘Malali’ or ‘Sugar Baby’. Parents, F1, F2, and back cross progenies were evaluated for resistance in growth chambers at the cotyledon stage and the 4-leaf stage and in the field, at the 15-leaf stage. Resistance at the cotyledon stage was controlled by a single, partially dominant gene, whereas at the 4-leaf stage or the 15-leaf stage resistance was controlled by three complimentary, partially dominant genes. Crosses made among these resistant accessions revealed that BIU 119 and PI 189225 carry the same genes for resistance, whereas PI 482312 shares two out of three genes with both BIU 119 and PI 189225. A breeding line with high resistance level and good fruit qualities was developed from BIU 119 × HA5500.

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UPDATE ON POWDERY MILDEW RESISTANCE SCREENING IN WATERMELON

HortScience ◽

10.21273/hortsci.40.3.871a ◽

2005 ◽

Vol 40 (3) ◽

pp. 871a-871

Author(s):

Angela R. Davis ◽

Todd C. Wehner ◽

Amnon Levi ◽

Stephen R. King

Keyword(s):

United States ◽

South Carolina ◽

Powdery Mildew ◽

Resistance Genes ◽

Citrullus Lanatus ◽

Germplasm Collection ◽

The United States ◽

The Past ◽

Race 1 ◽

Race 2

Powdery mildew has been reported on Citrullus lanatus in Africa and Europe for the past nine years, and in the United States for the past 6 years. During this time, it has occurred in the main watermelon production areas in the U.S. and has been documented in nine states (South Carolina, Georgia, Florida, Oklahoma, Texas, Maryland, New York, Arizona, and California). This is of great concern to the watermelon industry since powdery mildew is difficult to control and can have a severe impact on yield and fruit quality due to loss of photosynthetic area and sunscald. Finding resistant C. lanatus germplasm is needed for the development of commercial varieties containing this resistance. This report summarized the status of an ongoing project to screen the entire USDA–ARS C. lanatus germplasm collection. Currently, the collection is being screened for race 1 and race 2 Podosphaera xanthii (syn. Sphaerotheca fuliginea auct. p.p.), the causal agent of powdery mildew in C. lanatus in the United States. Resistance genes appear to exist for both races and the genes conferring resistance to race 1 appear to be different than race 2 resistance genes. Allelism tests are currently in process to determine the number of resistance genes present.

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Characterization of Watermelon (Citrullus lanatus var. citroides) Germplasm for Resistance to Root-knot Nematodes

HortScience ◽

10.21273/hortsci.42.7.1530 ◽

2007 ◽

Vol 42 (7) ◽

pp. 1530-1533 ◽

Cited By ~ 25

Author(s):

Judy A. Thies ◽

Amnon Levi

Keyword(s):

Root System ◽

Citrullus Lanatus ◽

Sources Of Resistance ◽

Root Knot Nematodes ◽

Plant Introductions ◽

Race 1 ◽

Race 2 ◽

Moderate Resistance ◽

Moderately Resistant

Root-knot nematodes (Meloidogyne spp.) cause extensive damage to watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus], and resistance to root-knot nematodes has not been identified in any watermelon cultivar. Twenty-six U.S. Plant Introductions (PIs) of Citrullus lanatus (Thunb.) Matsum. & Nakai var. citroides (L. H. Bailey) Mansf., one PI of C. lanatus var. lanatus, and three PIs of Citrullus colocynthis (L.) Schrad. were evaluated in greenhouse tests for resistances to Meloidogyne incognita (Kofoid & White) Chitwood race 3 and Meloidogyne arenaria (Neal) Chitwood race 2. Twenty-three of the C. lanatus var. citroides PIs and the C. lanatus var. lanatus PIs were previously identified as moderately resistant to M. arenaria race 1. Overall, the C. lanatus var. citroides PIs exhibited low to moderate resistance, and the C. lanatus var. lanatus and C. colocynthis PIs were susceptible to both M. incognita race 3 and M. arenaria race 2. The C. lanatus var. citroides PI 482303 was the most resistant PI with gall index (GI) = 2.88 and reproductive index (RI) = 0.34 for M. incognita race 3 and GI = 3.46 and RI = 0.38 for M. arenaria race 2 (1 = no galling; 5 = 26% to 38% root system galled; 9 = 81% to 100% root system galled). These results demonstrate that there is significant genetic variability within C. lanatus var. citroides for reaction to M. incognita and M. arenaria race 2, and several C. lanatus var. citroides PIs may provide sources of resistance to root-knot nematodes.

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