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a Conidia of Golovinomyces cichoracearum (Gc) (bar=10 µm), b Conidia of Podosphaera xanthii (Px) (bar=10 µm), c Golovinomyces cichoracearum cleistothecium with asci and ascospores (bar=20 µm), d Hyperparasitic fungus Ampelomyces quisqualis pycnidium on Golovinomyces cichoracearum basal cell of conidiophore (bar=10 µm)
Source publication
The occurrence and geographic distribution of powdery mildew on cucurbits was studied in the Czech Republic, Austria, France,
Germany, Great Britain, Italy, Slovakia, Slovenia, Spain, Switzerland, the Netherlands, as well as in Turkey and Israel, during
the period 1995–2000. In total, 599 leaf samples with powdery mildew symptoms were collected fro...
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Citations
... PM: Melon PM is often caused by Podosphaera xanthii (Px) and Golovinomyces cichoracearum (Gc) (Křístková et al. 2009, Li et al. 2017. G. cichoracearum occurs powderly in field environments in temperate and cold regions. ...
Genome editing technologies are promising for conventional mutagenesis breeding, which takes a long time to remove unnecessary mutations through backcrossing and create new lines because they directly modify the target genes of elite strains. In particular, this technology has advantages for traits caused by the loss of function. Many efforts have been made to utilize this technique to introduce valuable features into crops, including maize, soybeans, and tomatoes. Several genome-edited crops have already been commercialized in the US and Japan. Melons are an important vegetable crop worldwide, produced and used in various areas. Therefore, many breeding efforts have been made to improve its fruit quality, resistance to plant diseases, and stress tolerance. Quantitative trait loci (QTL) analysis was performed, and various genes related to important traits were identified. Recently, several studies have shown that the CRISPR/Cas9 system can be applied to melons, resulting in its possible utilization as a breeding technique. Focusing on two productivity-related traits, disease resistance, and fruit quality, this review introduces the progress in genetics, examples of melon breeding through genome editing, improvements required for breeding applications, and the possibilities of genome editing in melon breeding.
... However, watermelon faces the persistent threat of powdery mildew, a devastating fungal that can afflict the plant from seedling to maturity. This pathogen manifests as a white, powdery layer on leaves, stems, and petioles, progressively spreading and resulting in premature leaf senescence, diminished fruit yield, and compromised quality, ultimately precipitating substantial economic losses (Keinath 2000;Keinath and DuBose 2004;McGrath 2001;Davis et al. 2007;Křístková et al. 2009). ...
Key message
ClLOX, is located on chromosome 2 and encodes a lipoxygenase gene, which induced watermelon powdery mildew resistance by inhibiting pathogen spread.
Abstract
Powdery mildew is one of the most severe fungal diseases reducing yield and quality of watermelon (Citrullus lanatus L.) and other cucurbit crops. Genes responsible for powdery mildew resistance in watermelon are highly valuable. In this study, we first identified the QTL pm-lox for powdery mildew resistance in watermelon, located within a 0.93 Mb interval of chromosome 2, via XP-GWAS method using two F2 populations. The F2:3 families from one of the F2 populations were then used for fine-mapping the pm-lox locus into a 9,883 bp physical region between 29,581,906 and 29,591,789, containing only two annotated genes. Of these, only ClG42_02g0161300 showed a significant differential expression between the resistant and susceptible lines after powdery mildew inoculation based on RNA sequencing (RNA-seq) and qRT-PCR analysis, and is designated ClLOX. Derived Cleaved Amplified Polymorphic Sequence (dCAPs) markers were developed and validated. In addition, our tests showed that the resistance was anti-spread rather than anti-infection of the pathogen. This study identified a new resistance gene (ClLOX), provided insights into the mechanism of powdery mildew resistance, and developed a molecular marker for watermelon breeding.
... Out of 28, three races-1, 2, and 3-were reported from the USA. Similarly, other races-0, 4, and 5-were reported in France and four races-1, N1 (race 6), N2 (race 7) and 5-were reported in Japan [12,17]. By comparing the interaction of 22 melon accessions against 28 races of P. xanthii, McCreight [18] identified eight variants of race 1 and six variants of race 2. In addition, Kim et al. [19] reported the existence of race N5, based on its distinctive reaction on 10 differential melon lines. ...
Powdery mildew caused by Podosphaera xanthii is a serious fungal disease which causes severe damage to melon production. Unlike with chemical fungicides, managing this disease with resistance varieties is cost effective and ecofriendly. But, the occurrence of new races and a breakdown of the existing resistance genes poses a great threat. Therefore, this study aimed to identify the resistance locus responsible for conferring resistance against P. xanthii race KN2 in melon line IML107. A bi-parental F2 population was used in this study to uncover the resistance against race KN2. Genetic analysis revealed the resistance to be monogenic and controlled by a single dominant gene in IML107. Initial marker analysis revealed the position of the gene to be located on chromosome 2 where many of the resistance gene against P. xanthii have been previously reported. Availability of the whole genome of melon and its R gene analysis facilitated the identification of a F-box type Leucine Rich Repeats (LRR) to be accountable for the resistance against race KN2 in IML107. The molecular marker developed in this study can be used for marker assisted breeding programs.
... xanthii) and Golovinomyces cichoracearum (de Candolle) Heluta (G. cichoracearum), were identified in melon (Kuzuya et al. 2006;Kristkova et al. 2009;Li et al. 2017;Hong et al. 2018). In P. xanthii, over 28 physiological races have been identified based on their responses to various melon varieties, and which are relatively dispersed across various geographical regions worldwide (Bardin et al. 1999;Hosoya et al. 1999;McCreight 2006). ...
Development of PCR-based markers associated with powdery mildew resistance using bulked segregant analysis (BSA-seq) in melon. Czech J. Genet. Plant Breed. Abstract: Powdery mildew (PM) is a fungus that causes disease in both the field and the greenhouse. Utilizing resistant cul-tivars is the most effective approach of disease management. To develop insertion-deletion (InDel) markers associated to this trait, the whole genomes of the PM resistant line M17050 (P1) and the PM-susceptible line 28-1-1 (P2) were sequenced. A total of 1 200 InDels, with an average of 100 markers per chromosome, were arbitrarily chosen from the sequencing data for experimental validation. One hundred InDel markers were ultimately selected due to their informative genetic bands. Further, an F 2 segregating population of melons generated from these two parents was inoculated by the PM pathogen. Based on bulk segregant analysis (BSA) using these 100 InDel markers, the powdery mildew resistance was associated with the genomic region LVpm12.1 on the melon chromosome 12. This region overlapped the previously described quantitative trait locus (QTL)-hotspot area carrying multiple PM-resistance QTLs. Moreover, conventional QTL mapping analysis was done, which located LVpm12.1 in the region between 22.72 and 23.34 Mb, where three highly polymorphic InDel markers MIn-Del89, MInDel92, and MInDel93 were detected. Therefore, these markers could be used to track this resistance locus in melon while the lines carrying this locus could be employed in PM melon resistance breeding programs after validation tests.
... Ampelomyces spp. naturally parasitized the overwintering chasmothecia of E. necator in conventional, organic, and untreated vineyards of northern Italy(Angeli et al. 2009).The natural parasitism by A. quisqualis was reported on Golovinomyces cichoracearum and P. xanthii responsible for disease development in certain cucurbits plants, for instance, Cucumis melo, C. sativus, Cucurbita pepo, C. maxima, and Citrullus lanatus from the Czech Republic, Austria, France, Germany, Great Britain, Italy, Slovakia, Slovenia, Spain, Switzerland, the Netherlands, as well as in Turkey and Israel(Křístková et al. 2009).Co-existence of A. quisqualis Ces. ex Schlech withOidium euonymi-japonica, a fungal phytopathogen of powdery mildew of Buxus trees, Euonymus japonica was found in Gorgan, the Golestan province, Iran(Naseripour et al. 2014). ...
... Powdery mildew (PM) is a serious disease affecting many crops, including cucurbits in many countries [1][2][3][4][5][6][7][8][9][10][11][12][13]. PM causes leaf damage and significantly reduces cucurbit A single conidium from melon leaves displaying PM symptoms was isolated in 2013 in Japan. ...
In this study, we evaluated the effectiveness of hyperparasitic fungi in controlling powdery mildew (PM). In a greenhouse, we spray-inoculated single colonies of the melon PM-causing fungus Podosphaera xanthii strain KMP-6N at three different fungal developmental stages (i.e., 5, 10, and 15 days old) with spores of the hyperparasitic fungus Ampelomyces sp. strain Xs-q. After spray inoculation, we collected and counted KMP-6N conidia produced as asexual progeny from PM colonies using an electrostatic rotational spore collector. Collector insulator films were replaced at 24 h intervals until KMP-6N ceased to release additional progeny conidia. Conidial releases from each of the single Xs-q-inoculated KMP-6N colonies gradually reduced, then stopped within ca. 4 and 8 days of the first treatment in 5- and 10-day-old KMP-6N colonies, and within ca. 20 days of the second spray treatment in 15-day-old KMP-6N colonies, respectively. The total numbers of asexual progeny conidia collected from single 5-, 10-, and 15-day-old colonies were ca. 156, 1167, and 44,866, respectively. After electrostatic spore collection, conidiophores in Xs-q-uninoculated KMP-6N colonies appeared normal, whereas almost all conidiophores in 5- and 10-day-old Xs-q-inoculated KMP-6N colonies were completely deformed or collapsed due to the infection of the hyperparasitic fungus. This is the first study to apply electrostatic and digital microscopic techniques to clarify the impact of fungal hyperparasitism on mycohost survival, and, in particular, to assess quantitatively and visually the suppression of conidial release from any PM colonies infected with Ampelomyces.
... In the later stage of infection, the leaves gradually turn yellow, die, and fall off, exposing the fruit to sunlight, which will eventually lead to the overall death of the plant late in growth, seriously affecting the quality and yield of melon (Kuzuya et al., 2003). Mainly, Podosphaera xanthii (Px) and Golovinomyes cichoracearum (Gc) are the two main fungi that are mainly responsible for the occurrence of PM disease in Cucurbitaceae crops (Krǐśtkováet al., 2009). ...
Powdery mildew (PM) is one of the main fungal diseases that appear during the cultivation of the melon fruit crop. Mildew Resistance Locus “O” (MLO) is known as a gene family and has seven conserved transmembrane domains. An induced functional loss of a specific MLO gene could mainly confer PM resistance to melons. However, the genomic structure of MLO genes and its main role in PM resistance still remain unclear in melon. In this study, bioinformatic analysis identified a total of 14 MLO gene family members in the melon genome sequence, and these genes were distributed in an uneven manner on eight chromosomes. The phylogenetic analysis divided the CmMLO genes into five different clades, and gene structural analysis showed that genes in the same clade had similar intron and exon distribution patterns. In addition, by cloning the CmMLO gene sequence in four melon lines, analyzing the CmMLO gene expression pattern after infection, and making microscopic observations of the infection pattern of PM, we concluded that the CmMLO5 (MELO3C012438) gene plays a negative role in regulating PM-resistance in the susceptible melon line (Topmark), and the critical time point for gene function was noticed at 24 and 72 hours after PM infection. The mutational analysis exhibited a single base mutation at 572 bp, which further results in loss of protein function, thus conferring PM resistance in melon. In summary, our research evidence provides a thorough understanding of the CmMLO gene family and demonstrates their potential role in disease resistance, as well as a theoretical foundation for melon disease resistance breeding.
... PM disease can be visualized with whitish spots that can significantly infect the aerial plant parts, including petioles, leaves, tendrils, and stems, and ultimately reduce the fruit quality. PM is caused by several fungal pathogens of the Ascomycota phylum, particularly from Podosphaera xanthii (formerly Sphaerotheca fuliginea) and Golovinomyces cichoracearum (formerly Erysiphe cichoracearum) (Křístková et al. 2009). Since then, more than 28 physiological races, including races 0, 1, 2, USA, 2, France, 3, 4, 5, N1 (race 6), N2 (race 7), N3, and N4, have been characterized based on the reactions of P. xanthii isolates to melon differential lines (Harwood and Markarian 1968;Sowell and Corley 1974;Thomas 1978;Floris and Alvarez 1995;Mohamed et al. 1995;Pitrat et al. 1996Pitrat et al. , 1998Alvarez et al. 2000;Cohen et al. 2002;Bertrand 2002;McCreight 2006). ...
Key message
Identified a recessive gene (Cmpmr2F) associated with resistance to infection by the powdery mildew causing agent Podosphaera xanthii race 2F.
Abstract
Powdery mildew (PM) is one of the most destructive fungal diseases of melon, which significantly reduces the crop yield and quality. Multiple studies are being performed for in-depth genetic understandings of PM-susceptibility or -resistance mechanisms in melon plants, but the holistic knowledge of the precise genetic basis of PM-resistance is unexplored. In this study, we characterized the recessive gene “Cmpmr2F” and found its association with resistance against the PM causative agent “Podosphaera xanthii race 2F.” Fine genetic mapping revealed the major-effect region of a 26.25-kb interval on chromosome 12, which harbored the Cmpmr2F gene corresponding to the MELO3C002403, encoding allantoate amidohydrolase. The functional gene annotation, expression pattern, and sequence alignment analyses were carried out using two contrast parent lines of melon “X055” PM-susceptible and “PI 124112” PM-resistant. Further, gene silencing of Cmpmr2F using virus-induced gene silencing (VIGS) significantly increased PM-resistance in the susceptible plant. In contrast to the previously reported studies, we identified that Cmpmr2F-silenced plants showed no impairment in growth due to less apparent negative effects in silenced melon plants. So, it is believed that the Cmpmr2F gene has great potential for further breeding studies to increase the P. xanthii race 2F resistance in melon. In short, our study provides new genetic resources and a solid foundation for further functional analysis of PM-resistance genes in melon, as well as powerful molecular markers for marker-assisted breeding aimed at developing new melon varieties resistant to PM infection.
... The disease is caused by two pathogens: Podosphaera xanthii (Castagne) U. Braun and Shishkoff (synonym Sphaerotheca xanthii (Castagne) L. Junell) and Golovinomyces orontii (DC) V.P. Heluta (synonyms Erysiphe cichoracearum DC, G. cichoracearum DC). The most prevalent species is P. xanthii but in some countries, G. orontii can also be found [2,3]. P. xanthii occurs more frequently in temperate subtropical and tropical areas, while G. orontii occurs more frequently in temperate areas under field conditions [2]. ...
... The most prevalent species is P. xanthii but in some countries, G. orontii can also be found [2,3]. P. xanthii occurs more frequently in temperate subtropical and tropical areas, while G. orontii occurs more frequently in temperate areas under field conditions [2]. The infection is evident by the development of white mycelia on leaves and stems and, in severe cases, also affects fruits and floral structures. ...
Powdery mildew caused by Podosphaera xanthii is among the most threatening fungal diseases affecting melons on the Mediterranean coast. Although the use of genetic resistance is a highly recommended alternative to control this pathogen, many races of this fungus have been described and, therefore, resistance is usually overcome; thus, breeding for resistance to this pathogen is a challenge. Several melon genotypes carrying resistance to powdery mildew have been described but their agronomical and fruit characters are usually far away from the required melon types in many commercial markets. Taking this into consideration, looking for novel sources of resistance in Tunisian landraces is a very convenient step to obtain new resistant melon varieties/hybrids suitable for Mediterranean markets. Several Tunisian melon landraces have been tested against three common races in Mediterranean regions (Race 2, Race 3.5, and Race 5), using phenotypic approaches in two independent experiments (artificial inoculations in a growth chamber and natural conditions of infection in a greenhouse). The results of the artificial inoculations showed that all the tested landraces were susceptible to Race 3.5 and Race 5 and several landraces were resistant to Race 2. Under natural conditions of infection, Race 2 of P. xanthii was the race prevalent in the plot and the resistance of TUN-16, TUN-19, and TUN-25 was confirmed. The found resistances were race-specific and underlie a high genetic influence reflected in the high value of the estimated heritability of 0.86. These resistant landraces should be considered as a potential source of resistance in breeding programs of melons belonging to inodorus and reticulatus groups, but further research is necessary to elucidate the genetic control of the found resistances and to provide useful molecular markers linked to P. xanthii Race 2 resistance.
... The pathogen of cucumber powdery mildew, Podosphaera xanthii, identified through a diagnostic guide (Kristkova et al., 2009), was collected from the greenhouse of the Faculty of Fisheries and Protection of Waters (FFPW) in the Czech Republic, where the natural infestation was recorded in August 2020. The pathogen was cultured on leaves of healthy cucumber plants (variety Superstar F1, Semo a.s., Czech Republic) and grown for two weeks in an MLR-352 growth chamber (25 ± 1°C; 16h of light, 60-65% RH (Akribis, UK). ...
Aquaponics has the potential to produce sustainable and accessible quality food through the integration of hydroponics and aquaculture. Plants take up dissolved nutrients in fish wastewater, allowing water reuse for fish. However, the simultaneous presence of fish and plants in the same water loop has made phytosanitary treatments of diseases such as powdery mildew problematic due to risks of toxicity for fish and beneficial bacteria, limiting its commercialization. Entomopathogenic and mycoparasitic fungi have been identified as safe biological control agents for a broad range of pests. This study aimed to investigate the efficacy of entomopathogenic fungi, Lecanicillium attenuatum (LLA), Isaria fumosorosea (IFR), and mycoparasitic fungus Trichoderma virens (TVI) against Podosphaera xanthii. Also, we investigated the possible harmful effects of the three fungal biocontrol agents in aquaponics by inoculating them in aquaponics water and monitoring their survival and growth. The findings showed that the three biocontrol agents significantly suppressed the powdery mildew at 10⁷ CFU/ml concentration. Under greenhouse conditions (65-73% relative humidity (RH)), a significant disease reduction percentage of 85% was recorded in L. attenuatum-pretreated leaves. IFR-treated leaves had the least AUDPC (area under disease progress curve) of ~434.2 and disease severity of 32% under 65-73% RH. In addition, L. attenuatum spores were the most persistent on the leaves, the spores population increased to 9.54 × 10³ CFUmm⁻² from the initial 7.3 CFUmm⁻² under 65-73%. In contrast, in hydroponics water, the LLA, IFR, and TVI spores significantly reduced by more than 99% after 96 hrs. Initial spore concentrations of LLA of 10⁷ CFU/ml spores were reduced to 4 x 10³ CFU after 96 hrs. Though the results from this study were intended for aquaponics systems, relevance of the results to other cultivation systems are discussed.
