scholarly journals Cucurbit Powdery Mildew-resistant Bitter Gourd Breeding Lines Reveal Four Races of Podosphaera xanthii in Asia

HortScience ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 337-341 ◽  
Author(s):  
Narinder P.S. Dhillon ◽  
Supannika Sanguansil ◽  
Supornpun Srimat ◽  
Roland Schafleitner ◽  
B. Manjunath ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Smallholder Farmers ◽  
Bitter Gourd ◽  
Yield Potential ◽  
Podosphaera Xanthii ◽  
Asian Countries ◽  
Sources Of Resistance ◽  
Breeding Lines ◽  
Race 1 ◽  
Cucurbit Powdery Mildew

Bitter gourd (Momordica charantia L.) is a commercially and nutritionally important market vegetable in Asia cultivated mainly by smallholder farmers. Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is a nearly ubiquitous and serious fungal disease of bitter gourd. Five bitter gourd breeding lines (THMC 113, THMC 143, THMC 153, THMC 167, and THMC 170) were selected at the World Vegetable Center for resistance to a local isolate of Px in Kamphaeng Saen, Thailand. We evaluated the resistance potential of these five inbred lines against local isolates of Px at 12 locations in five Asian countries. Plants were inoculated with the respective local Px isolate 15 and 30 days after transplanting and additional Px-infected plants of the inoculated control were interplanted throughout each test. Plants were rated 60 days after transplanting for CPM reaction using a 0 (no evidence of infection) to 5 (>75% infection evident on individual leaves) disease severity scale. THMC 153 and THMC 167 were resistant to the local race of Px in all locations, whereas THMC 143 was observed resistant in all test locations except one in China. THMC 113 was resistant in each location except one in India. THMC 170 was susceptible in three locations in India. The multilocation tests revealed four unique Px races on bitter gourd in different Asian countries and sources of resistance for breeding CPM-resistant bitter gourd cultivars. Six strains of Px isolated from other cucurbits (Cucumis and Cucurbita) and representing five melon CPM races were unable to infect the susceptible M. charantia accession THMC 144 and the five resistant breeding lines, indicating pathotype differences between them and an isolate of M. charantia origin typed as race 1 on melon. THMC 143 and THMC 167, which originated from India, exhibited good yield potential in trials conducted in Thailand, Myanmar, Vietnam, and Bangladesh.

scholarly journals Inheritance of Resistance to Cucurbit Powdery Mildew in Bitter Gourd

HortScience ◽  
2019 ◽  
Vol 54 (6) ◽  
pp. 1013-1016 ◽  
Author(s):  
Narinder P.S. Dhillon ◽  
Supannika Sanguansil ◽  
Supornpun Srimat ◽  
Suwannee Laenoi ◽  
Roland Schafleitner ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Bitter Gourd ◽  
Inheritance Of Resistance ◽  
Breeding Lines ◽  
Resistant Lines ◽  
Recessive Genes ◽  
High Level ◽  
Important Disease ◽  
Level Resistance ◽  
Cucurbit Powdery Mildew

Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is an economically important disease of bitter gourd (BG; Momordica charantia) in Asia. High-level resistance to CPM is known in various BG accessions that have been used to develop BG breeding lines that originated in different countries. BG breeding lines THMC 113 (Belize), THMC 143 (India), THMC 153 (Thailand), THMC 167 (India), and THMC 170 (Taiwan) possess high-level resistance to BG Px race (BG-CPM), designated Mc-1 from a field at Kamphaeng Saen, Thailand, whereas THMC 144 (India) is susceptible. Our objective was to determine the inheritance of resistance to BG-CPM race Mc-1. To that end, THMC 144 (India) was crossed with the five resistant lines. The parents and their respective F1, F2, backcross progenies were evaluated for BG-CPM disease severity in inoculated field and growth chamber tests. Resistance to BG-CPM race Mc-1 in the five resistant lines was controlled by at least two independent, recessive genes. Intercrosses of the BG-CPM–resistant lines revealed allelic resistances in four of the breeding lines: THMC 113, THMC 153, THMC 167, and THMC 170. Resistance in THMC 143 was clearly non-allelic for resistance to BG-CPM with the other four BG-CPM–resistant lines.

scholarly journals Transformation of the cucurbit powdery mildew pathogen Podosphaera xanthii by Agrobacterium tumefaciens

2016 ◽  
Vol 213 (4) ◽  
pp. 1961-1973 ◽  
Author(s):  
Jesús Martínez‐Cruz ◽  
Diego Romero ◽  
Antonio Vicente ◽  
Alejandro Pérez‐García
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Powdery Mildew ◽  
Podosphaera Xanthii ◽  
Powdery Mildew Pathogen ◽  
Cucurbit Powdery Mildew

scholarly journals Resistance to Phytophthora nicotianae in Tobacco Breeding Lines Derived from Variety Beinhart 1000

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Kestrel McCorkle ◽  
Ramsey Lewis ◽  
David Shew
Keyword(s):  
Partial Resistance ◽  
Phytophthora Nicotianae ◽  
Sources Of Resistance ◽  
Black Shank ◽  
Breeding Lines ◽  
Stem Resistance ◽  
Race 1 ◽  
Low Levels ◽  
Dh Lines ◽  
Rapid Emergence

Black shank, caused by Phytophthora nicotianae, is managed primarily by host resistance. The rapid emergence of race 1 eliminated the usefulness of available complete resistance, leading breeders to search for new sources of resistance. Cigar tobacco ‘Beinhart 1000’ (BH) is highly resistant to all races of P. nicotianae. Doubled-haploid (DH) lines from a cross of BH and the susceptible ‘Hicks’ were evaluated for black shank resistance, and quantitative trait loci (QTL) on linkage groups (LGs) 4 and 8 accounted for >43% of the phenotypic variation in resistance. Forty-three DH lines and parents were evaluated, and genotypes with one or both QTL from BH on LGs 4 and 8 had increased incubation periods and decreased root rot but higher final inoculum levels than genotypes with neither QTL. A low level of stem resistance was observed in BH and DH lines with the QTL from BH on LG 4 but not LG 8. Low levels of leaf resistance were seen for Hicks, BH, and DH lines with both QTL from BH on LG 4 and 8. The partial resistance from BH has not been used commercially and may provide an increase in level of partial resistance in future tobacco varieties.

First Report of Resistance to Boscalid in Podosphaera xanthii, Cucurbit Powdery Mildew, in South Carolina

2018 ◽  
Vol 19 (3) ◽  
pp. 220-221 ◽  
Author(s):  
Anthony P. Keinath ◽  
Gabriel Rennberger ◽  
Chandrasekar S. Kousik
Keyword(s):  
South Carolina ◽  
Powdery Mildew ◽  
Fungicide Resistance ◽  
Southern United States ◽  
Podosphaera Xanthii ◽  
Powdery Mildew Fungus ◽  
Action Committee ◽  
Summer Squash ◽  
Laboratory Bioassays ◽  
Cucurbit Powdery Mildew

Resistance to boscalid, one of the older succinate-dehydrogenase inhibitors (SHDI) in Fungicide Resistance Action Committee (FRAC) code 7, was detected in Podosphaera xanthii, the cucurbit powdery mildew fungus, in South Carolina in July 2017. Resistance to the field rate (682 ppm) of boscalid was confirmed in greenhouse experiments and laboratory bioassays conducted on summer squash plants and cotyledons, respectively, that had been treated with a range of boscalid concentrations. This report is the first documentation of resistance to boscalid in P. xanthii in the southern United States.

scholarly journals Monitoring Methyl Benzimidazole Carbamate-Resistant Isolates of the Cucurbit Powdery Mildew Pathogen, Podosphaera xanthii, Using Loop-Mediated Isothermal Amplification

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1515-1524 ◽  
Author(s):  
Alejandra Vielba-Fernández ◽  
Antonio de Vicente ◽  
Alejandro Pérez-García ◽  
Dolores Fernández-Ortuño
Keyword(s):  
Amino Acid ◽  
Powdery Mildew ◽  
Amino Acid Change ◽  
Color Change ◽  
Isothermal Amplification ◽  
Podosphaera Xanthii ◽  
Lamp Product ◽  
Loop Mediated Isothermal Amplification ◽  
Cucurbit Powdery Mildew ◽  
Β Tubulin

Powdery mildew, caused by the fungus Podosphaera xanthii, is one of the most economically important diseases affecting cucurbit crops in Spain. Currently, chemical control offers the most efficient management of the disease; however, P. xanthii isolates resistant to multiple classes of site-specific fungicides have been reported in the Spanish cucurbit powdery mildew population. In previous studies, resistance to the fungicides known as methyl benzimidazole carbamates (MBCs) was found to be caused by the amino acid substitution E198A on β-tubulin. To detect MBC-resistant isolates in a faster, more efficient, and more specific way than the traditional methods used to date, a loop-mediated isothermal amplification (LAMP) system was developed. In this study, three sets of LAMP primers were designed. One set was designed for the detection of the wild-type allele and two sets were designed for the E198A amino acid change. Positive results were only obtained with both mutant sets; however, LAMP reaction conditions were only optimized with primer set 2, which was selected for optimal detection of the E198A amino acid change in P. xanthii-resistant isolates, along with the optimal temperature and duration parameters of 65°C for 75 min, respectively. The hydroxynaphthol blue (HNB) metal indicator was used for quick visualization of results through the color change from violet to sky blue when the amplification was positive. HNB was added before the amplification to avoid opening the lids, thus decreasing the probability of contamination. To confirm that the amplified product corresponded to the β-tubulin gene, the LAMP product was digested with the enzyme LweI and sequenced. Our results show that the LAMP technique is a specific and reproducible method that could be used for monitoring MBC resistance of P. xanthii directly in the field.

scholarly journals FIELD EVIDENCE FOR A NEW RACE OF POWDERY MILDEW ON MELON

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 888a-888 ◽  
Author(s):  
James D. McCreight ◽  
Michael D. Coffey ◽  
Thomas A. Turini ◽  
Michael E. Matheron
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Genetic Resistance ◽  
Podosphaera Xanthii ◽  
Sphaerotheca Fuliginea ◽  
Imperial Valley ◽  
Field Evidence ◽  
Race 1 ◽  
New Race ◽  
The U.S

Races 1 and 2 of Podosphaera xanthii (syn. Sphaerotheca fuliginea) were defined in Imperial Valley, Calif. 1938 when P. xanthii overcame genetic resistance in `PMR 45'. Race 3 was first observed in the U.S. in 1976 in Texas; 15 additional races of P. xanthii have been reported in the literature since 1996. Races 1 and 2 have been common in Arizona and California based upon the effectiveness of the powdery mildew resistance genes in commercially available melon cultivars grown in these states. Field data from 11 commonly used melon P. xanthii race differentials in 2001 and 2002 indicated the presence of race 1 in the Imperial Valley and San Joaquin Valley of California, and Yuma, Arizona. In spring 2003, the powdery mildew race situation changed. The first evidence was the occurrence of a severe and widespread infection of powdery mildew in a commercial cantaloupe field. The 11 powdery mildew race differentials were susceptible to powdery mildew in a nearby replicated field test. PI 313970, a melon from India, was resistant to this apparent new race of powdery mildew.

scholarly journals Genetic Resistance of Lactuca spp. against Fusarium oxysporum f. sp. lactucae Race 1

HortScience ◽  
2021 ◽  
pp. 1-13
Author(s):  
Jesse J. Murray ◽  
Gulnoz Hisamutdinova ◽  
Germán V. Sandoya ◽  
Richard N. Raid ◽  
Stephanie Slinski
Keyword(s):  
Fusarium Oxysporum ◽  
Durable Resistance ◽  
Management Strategies ◽  
Genetic Resistance ◽  
Segregation Ratio ◽  
Sources Of Resistance ◽  
Breeding Lines ◽  
Plant Introductions ◽  
Soil Pathogen ◽  
Race 1

Fusarium wilt of lettuce is caused by the pathogen Fusarium oxysporum f. sp. lactucae (Fol) and is a growing threat to global lettuce production. Fol was first detected in Florida in 2017 and was subsequently confirmed as race 1. Management strategies for this long-persisting soil pathogen are limited, time-consuming and expensive, and they may lack efficacy. Identifying diverse sources of genetic resistance is imperative for breeding adapted cultivars with durable resistance. The objectives of this study were to identify sources of resistance against a race 1 isolate of Fol in Florida, delineate the relationship between foliar and taproot symptoms, and investigate the inheritance of resistance and partial resistance in two F2 populations. Thirteen experiments were conducted in greenhouse and field locations to characterize the diversity of genetic resistance in the genus Lactuca. Leaf cultivars Dark Lollo Rossa and Galactic; romaine breeding lines 43007, 60182, and C1145; and iceberg breeding line 47083 consistently exhibited low foliar and taproot disease symptoms. Resistance was not identified among the wildtype Lactuca or primitive plant introductions (PI) in this study based on taproot symptoms. An additional test was conducted to study the segregation pattern of Fol resistance between one resistant and one susceptible accession (R × S) and one partial resistant and one susceptible accession (PR × S). The F2 population from ‘60182 × PI 358001-1’ fit the expected segregation ratio for a single recessive locus model, whereas the ratio for ‘Dark Lollo Rossa × PI 358001-1’ did not fit either recessive or dominant single locus models. These sources of resistance are potential candidates for developing commercial cultivars with multiple resistance loci against Fol race 1, especially for the Florida lettuce production system.

scholarly journals Outbreak of Cucurbit Powdery Mildew on Watermelon Fruit Caused by Podosphaera xanthii in Southwest Florida

Plant Disease ◽  
2011 ◽  
Vol 95 (12) ◽  
pp. 1586-1586 ◽  
Author(s):  
C. S. Kousik ◽  
R. S. Donahoo ◽  
C. G. Webster ◽  
W. W. Turechek ◽  
S. T. Adkins ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
The United States ◽  
Tween 20 ◽  
Conidial Suspension ◽  
Podosphaera Xanthii ◽  
Its Sequence Analysis ◽  
Fruit Samples ◽  
Cucurbit Powdery Mildew ◽  
Fruit Surface

Cucurbit powdery mildew caused by the obligate parasite Podosphaera xanthii occurs commonly on foliage, petioles, and stems of most cucurbit crops grown in the United States. (3). However, in the field, fruit infection on cucurbits including watermelon (Citrullus lanatus), is rarely, if ever, observed (2). Consequently, it was atypical when severe powdery mildew-like symptoms were observed on seedless and seeded watermelon fruit on several commercial farms in southwestern Florida during November and December 2010. Severe powdery mildew was also observed on ‘Tri-X 313’ and ‘Mickey Lee’ fruit grown at SWFREC, Immokalee, FL. Infected fruit developed poorly and were not marketable. Powdery mildew symptoms were mainly observed on young immature fruit, but not on mature older fruit. Abundant powdery mildew conidia occurred on fruit surface, but not on the leaves. Conidia were produced in chains and averaged 35 × 21 μm. Observation of conidia in 3% KOH indicated the presence of fibrosin bodies commonly found in the cucurbit powdery mildew genus Podosphaera (3). Orange-to-dark brown chasmothecia (formerly cleisthothecia) containing a single ascus were detected on the surface of some fruit samples. Conidial DNA was subjected to PCR using specific primers designed to amplify the internal transcribed spacer (ITS) region of Podosphaera (4). The resulting amplicons were sequenced and found to be 100% identical to the ITS sequences of P. xanthii in the NCBI database (D84387, EU367960, AY450961, AB040322, AB040315). Sequences from the watermelon fruit isolate were also identical to several P. fusca (synonym P. xanthii), P. phaseoli (GQ927253), and P. balsaminae (AB462803) sequences. On the basis of morphological characteristics and ITS sequence analysis, the pathogen infecting watermelon fruit can be considered as P. xanthii (1,3,4). The powdery mildew isolate from watermelon fruit was maintained on cotyledons of squash (Cucurbita pepo, ‘Early Prolific Straight Neck’). Cotyledons and leaves of five plants each of various cucurbits and beans were inoculated with 10 μl of a conidial suspension (105conidia/ml) in water (0.02% Tween 20). Two weeks after inoculation, abundant conidia were observed on cucumber (Cucumis sativus, ‘SMR-58’) and melon (Cucumis melo) powdery mildew race differentials ‘Iran H’ and ‘Vedrantais’. However, no growth was observed on melon differentials ‘PI 414723’, ‘Edisto 47’, ‘PMR 5’, ‘PMR 45’, ‘MR 1’, and ‘WMR 29’ (2,3). The powdery mildew isolate from watermelon fruit behaved as melon race 1 (3). Mycelium and conidia were also observed on fruit surface of watermelon ‘Sugar Baby’ and a susceptible U.S. plant introduction (PI 538888) 3 weeks after inoculation. However, the disease was not as severe as what was observed in the fields in fall 2010. The pathogen did not grow on plants of Impatiens balsamina or on select bean (Phaseolus vulgaris) cultivars (‘Red Kidney’, ‘Kentucky Blue’, and ‘Derby Bush’), but did grow and produce abundant conidia on ‘Pinto bush bean’. Powdery mildew on watermelon fruit in production fields can be considered as a potentially new and serious threat requiring further studies to develop management strategies. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) A. R. Davis et al. J. Am. Soc. Hortic. Sci. 132:790, 2007. (3) M. T. McGrath and C. E. Thomas. In: Compendium of Cucurbit Diseases. American Phytopathological Society, St. Paul, MN, 1996. (4) S. Takamatsu and Y. Kano. Mycoscience 42:135, 2001.

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