Proteome Profiling of _Cucurbita pepo_ Phyllosphere After Infection by _Podosphaera xanthii_ and Application of _Reynoutriascalalinensis_ Extract  
[PERSON]  
1  
[PERSON]  
2 Biotechnology Division, Biomedical Research Research Foundation of the Academy of Athens, Soranou Efessiou 4, 11527 Athens, Attica, Greece; 2  
[PERSON]  
1  
[PERSON]  
1  
[PERSON]  
2 Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, Soranou Efessiou 4, 11527 Athens, Attica, Greece; 2  
and [PERSON]  
4  
Footnote 1: [[https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci)]([https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci))  
Footnote 2: [[https://www.mdpi.com/journals/article/pdf/11/11/11/11/11/11/11/11/11/11/11/11/11/11/11/111/111/11/11/111/111/111/111/111/111/111/111/11/111/111/111/111/111/111/111](https://www.mdpi.com/journals/article/pdf/11/11/11/11/11/11/11/11/11/11/11/11/11/11/11/111/111/11/11/111/111/111/111/111/111/111/111/11/111/111/111/111/111/111/111)]([https://www.mdpi.com/journals/article/pdf/11/11/11/11/11/11/11/11/11/11/11/11/11/11/11/111/111/11/11/111/111/111/111/111/111/111/111/11/111/111/111/111/111/111/111](https://www.mdpi.com/journals/article/pdf/11/11/11/11/11/11/11/11/11/11/11/11/11/11/11/111/111/11/11/111/111/111/111/111/111/111/111/11/111/111/111/111/111/111/111))  
taxonomically divided into three subspecies: (i) _C. pepo pepo_ including the edible-fruited pumpkin, zucchini, cocozelle, and vegetable marrow cultivar-groups, (ii) C. pepo ovifera including the edible acorn, scallop, crookneck, and straightneck cultivar-groups, along with wild ornamental gourds, and (iii) _C. pepo fraterna_ which comprise only wild populations. Edible cultivars are highly diverse in vine, flower, fruit shape, and color, and are valued globally as high-valued vegetables [2; 3]. Powdery mildew (PM) is one of the most severe fungal diseases affecting more than 10,000 plant hosts globally. PM fungi (_Erysiphaceae_) are plant pathogens with an obligate-biotrophic lifestyle, capable usually of both sexual and asexual reproduction. Currently there are 27 genera including 724 known species reported as PM [4; 5; 6; 7; 8]. Cucurbit PM is considered one of the most reported and severe diseases limiting cucurbit production. The disease is caused by either _Podosphaera xanthii_ or _Golovinomyces cichoracearum_, with the former species being the main causal agent of powdery mildew in cucurbits. It manifests as white mycelium on leaves, petioles, and stems, starting with chlorotic spots that progress to necrotic lesions. This leads to reduced plant growth due to inhibited photosynthesis and leaf desiccation, ultimately lowering fruit quality [5; 6; 7; 8]. Control of PM is typically achieved through regular application of chemical fungicides [5; 8; 9]. However, the prolonged use of fungicides has resulted in the emergence of PM strains that are less susceptible or resistant to different chemical compounds [9; 10; 11]. Breeding programs have developed commercial varieties and breeding lines with resistance or susceptibility loci and genes (i.e., Mildew Locus O (MLO); _Pm-0_) to PM, and to ongoing evaluation of new candidates from wild relative species (i.e., _Run1, Run2, Ren2-4; Pm-36; Ren6, Ren7_) [5; 12; 13; 14; 15; 16]. However, adaptation and evolution of pathogenic races even in tolerant/resistant plant genotypes hamper to a certain extent an effective control of the disease through resistant cultivars. Alternative approaches for mitigation of PM resistance development suggest a combinatory use of resistant crop varieties, limitation of chemical fungicides' applications, along with introduction of plant defense eliciting compounds [17; 18; 19]. Plant defense elicitors are natural compounds that, when applied, prime the plant's innate immune system and induce biochemical signaling cascades leading to defense responses [20; 21; 22].