Identification of a Causal Pathogen of Watermelon Powdery Mildew in Korea and Development of a Genetic Linkage Marker for Resistance in Watermelon (Citrullus lanatus)

2016 ◽  
Vol 34 (6) ◽  
Keyword(s):  
Powdery Mildew ◽  
Genetic Linkage ◽  
Citrullus Lanatus ◽  
Linkage Marker ◽  
Causal Pathogen

scholarly journals First Report of Erysiphe cichoracearum Infecting Hedera canariensis var. azorica in Italy

Plant Disease ◽  
1999 ◽  
Vol 83 (2) ◽  
pp. 198-198
Author(s):  
C. Nali
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Ornamental Plants ◽  
Morphological Characteristics ◽  
Hedera Helix ◽  
Cucumis Sativus L ◽  
First Report ◽  
Erysiphe Cichoracearum ◽  
English Ivy

A powdery mildew disease of variegated ivy (Hedera canariensis L. var. azorica) was observed on the Tyrrhenian coast in Tuscany (Italy) in spring 1998. Symptoms began as small, nearly circular reddish spots that later enlarged and coalesced. The hyaline mycelium produced abundant, ellipsoid conidia in long chains that ranged from 20 to 40 μm in length and from 12 to 25 μm in width. Cleistothecia were globose (100 to 120 μm diameter), dark brown (when mature) with a basal ring of mycelioid appendages, and contained several (up to 20) ovate asci, each generally containing two ascospores. Ascospores were hyaline, one-celled, ellipsoid (20 to 35 μm in length and 10 to 20 μm in width). The morphological characteristics of this fungus were those given for Erysiphe cichoracearum DC. Infection also was found on English ivy (Hedera helix L.). It is reported that this species is, occasionally, subject to powdery mildew caused by E. cichoracearum (1). Conidia from infected leaves were shaken onto leaves of melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai), lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.) and variegated and English ivy. After 7 days, the disease was observed on cucumber, melon, watermelon, tobacco, and variegated ivy. Examination confirmed that test plants were infected with E. cichoracearum. This is the first report of E. cichoracearum on variegated ivy in Italy. Reference: (1) P. P. Pirone. 1970. Diseases and Pests of Ornamental Plants. The Ronald Press, New York.

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

HortScience ◽  
2013 ◽  
Vol 48 (10) ◽  
pp. 1227-1230 ◽  
Author(s):  
Antonia Y. Tetteh ◽  
Todd C. Wehner ◽  
Angela R. Davis
Keyword(s):  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Dominant Gene ◽  
Breeding Strategy ◽  
Dominance Model ◽  
Narrow Sense Heritability ◽  
Stem Resistance ◽  
Nonallelic Interactions ◽  
Race 2 ◽  
Moderate Resistance

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.

scholarly journals A Genetic Linkage Map for Watermelon Based on Randomly Amplified Polymorphic DNA Markers

2001 ◽  
Vol 126 (6) ◽  
pp. 730-737 ◽  
Author(s):  
Amnon Levi ◽  
Claude E. Thomas ◽  
Xingping Zhang ◽  
Tarek Joobeur ◽  
Ralph A. Dean ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
New Hampshire ◽  
Genetic Linkage ◽  
Rapd Markers ◽  
Citrullus Lanatus ◽  
Randomly Amplified Polymorphic Dna ◽  
Linkage Groups ◽  
Rapd Primer ◽  
Race 1 ◽  
Linkage Distance

A genetic linkage [randomly amplified polymorphic DNA (RAPD)-based] map was constructed for watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] using a BC1 population [PI 296341-fusarium wilt resistant × New Hampshire Midget (fusarium susceptible)] × `New Hampshire Midget'. The map contains 155 RAPD markers, and a 700-base pair sequenced characterized amplified region (SCAR) marker that corresponds to a fragment produced by the RAPD primer GTAGCACTCC. This marker was reported previously as linked (1.6 cM) to race 1 fusarium wilt resistance in watermelon. The markers segregated to 17 linkage groups. Of these, 10 groups included nine to 19 markers, and seven groups included two to four markers. The map covers a genetic linkage distance of 1295 cM. Nine of the 10 large linkage groups contained segments with low (or no) level of recombination (0 to 2.6 cM) among markers, indicating that the watermelon genome may contain large chromosomal regions that are deficient in recombination events. The map should be useful for identification of markers linked closely to genes that control fruit quality and fusarium wilt (races 1 and 2) resistance in watermelon.

scholarly journals First Occurrence of Cucurbit Powdery Mildew Caused by Race 3-5 of Podosphaera fusca in Spain

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 1073-1073 ◽  
Author(s):  
J. A. Torés ◽  
J. M. Sánchez-Pulido ◽  
F. López-Ruiz ◽  
A. de Vicente ◽  
A. Pérez-García
Keyword(s):  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Morphological Characteristics ◽  
Fungal Growth ◽  
Powdery Mildew Fungus ◽  
First Occurrence ◽  
New Race ◽  
First Time ◽  
Cucurbit Powdery Mildew ◽  
Podosphaera Fusca

A new race of cucurbit powdery mildew was observed for the first time on melon (Cucumis melo) in three research greenhouses in the Axarquia area of southern Spain during the spring of 2008. Fungal growth appeared as white powdery colonies initially restricted to the upper leaf surfaces. Morphological characteristics of colonies, conidiophores, conidia, germ tubes, and appressoria indicated that the powdery mildew fungus was Podosphaera fusca (also known as P. xanthii) (3), a fungal pathogen extensively reported in the area (1). However, the fungus developed on plants of melon cv. PMR 6, which is resistant to races 1 and 2 of P. fusca, suggesting that the fungus could belong to race 3, a race of P. fusca not yet reported in Spain. Race determination was carried out by inoculating the third true leaf of a set of differential melon genotypes that were maintained in a greenhouse. Symptoms and colonization observed on cvs. Rochet, PMR 45, PMR 6, and Edisto 47 indicated that the isolates belonged to race 3-5 of P. fusca. Fungal strains of races 1, 2, and 5 of P. fusca (all present in Spain) were used as controls. Pathotype designation was determined by inoculating different cucurbit genera and species (2). In addition to melon, the isolates were pathogenic on zucchini (Cucurbita pepo) cv. Diamant F1, but failed to infect cucumber (C. sativus) cv. Marketer and watermelon (Citrullus lanatus) cv. Sugar Baby; therefore, the isolates were pathotype BC (2). Races 1, 2, 4, and 5 of P. fusca have been previously reported in the area (1). The occurrence of race 3-5 represents another challenge in the management of cucurbit powdery mildew in Spain. References: (1) D. del Pino et al. Phytoparasitica 30:459, 2002. (2) E. Křístková et al. Sci. Hortic. 99:257, 2004. (3) A. Pérez-García et al. Mol. Plant Pathol. 10:153, 2009.

scholarly journals Alternative Fungicide Spraying for the Control of Powdery Mildew Caused by Sphaerotheca fusca on Greenhouse Watermelon (Citrullus lanatus)

2014 ◽  
Vol 20 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Hyo-Jung Kang ◽  
Youngsang Kim ◽  
Bongtae Han ◽  
Taeil Kim ◽  
Jaegwan Noh ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Sphaerotheca Fusca

scholarly journals Evaluation of Watermelon and Related Species for Resistance to Race 1W Powdery Mildew

2007 ◽  
Vol 132 (6) ◽  
pp. 790-795 ◽  
Author(s):  
Angela R. Davis ◽  
Amnon Levi ◽  
Antonia Tetteh ◽  
Todd Wehner ◽  
Vincent Russo ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Plant Introduction ◽  
The United States ◽  
Common Disease ◽  
Podosphaera Xanthii ◽  
Sphaerotheca Fuliginea ◽  
Wild Type ◽  
Intermediate Resistance ◽  
Cultivated Species

Powdery mildew [Podosphaera xanthii (Castagne) Braun & Shishkoff (syn. Sphaerotheca fuliginea auct. p.p.)] is now a common disease on watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] in the United States. In this study, the entire available U.S. Plant Introduction collection of Citrullus Schrad. ex Eckl. & Zeyh. species was evaluated for resistance to P. xanthii race 1W. The collection consists of four Citrullus species and one Praecitrullus Pangalo species [C. lanatus var. citroides (L.H. Bailey) Mansf., C. colocynthis (L.) Schrad., C. rehmii De Winter, and P. fistulosus (Stocks) Pangalo]. Wild-type accessions tended to be more resistant more often than the cultivated species, C. lanatus var. lanatus. None were immune, eight of the 1573 accessions exhibited high levels of resistance, and another 86 demonstrated intermediate resistance. Stem and leaf disease severity were weakly correlated (r 2 = 0.64, P = 0.001). The majority of accessions having resistance were collected in Zimbabwe. Resistance was found in four species.

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