A genomics perspective on cucurbit-oomycete interactions

Abstract

Pseudoperonospora cubensis and Phytophthora capsici are plant pathogenic oomycetes that are severe threats to cucurbit cultivation because of the their global distribution, their broad host range among the Cucurbitaceae family, and their ability to overcome susceptibilities to host, environment, and chemical management. Historically, these pathogens have been extensively studied in terms of their life cycles and infection strategies in order to determine appropriate methods to manage disease. In recent years, the genomes of both pathogens have been sequenced, which will lead to greater opportunities for pathogen detection and will help researchers to better understand the host-pathogen interaction. In Ps. cubensis, the transcriptomes of both Ps. cubensis and Cucumis sativus (cucumber) have been sequenced, and this data is being analyzed to determine the function of Ps. cubensis effectors and the role of alternative splicing in the regulation of pathogen gene expression. Previous and ongoing work is being done to determine cucumber genes involved in resistance. In P. capsici, effectors have been identified in the genome sequence, and the genome being used to identify variation in different P. capsici isolates. Future work is needed to give biological meaning to genomics data and to determine mechanisms of pathogenicity in oomycetes and resistance in cucurbits. Herein, we will present an overview of the current and future objectives of genome-based research in this area, describing the molecular mechanisms of pathogen virulence and host response to infection.

“Jumping Jack”: Genomic Microsatellites Underscore the Distinctiveness of Closely Related Pseudoperonospora cubensis and Pseudoperonospora humuli and Provide New Insights Into Their Evolutionary Past

“…By using the historical specimens of both pathogens, we gained some evidence for an ongoing speciation within P. cubensis. Recent evidence from -omics research has added several important genomic and metabolic insights to the accumulated molecular and host-pathogen interactions and specificity evidence of oomycetes speciation (Burkhardt and Day, 2013;McGowan and Fitzpatrick, 2020;Rodenburg et al, 2020). These include alternative splicing in the effector genes (Savory et al, 2012;Summers et al, 2015b), recombination and partial reshuffling of the genetic material (Cohen and Rubin, 2012;Thomas et al, 2017b), and functionally, host jumps and geographic separation from the preferred host species, which necessitated the evolution of parasitic behavior by genetic adjustments (Dussert et al, 2019;Rahman et al, 2019;Thines, 2019;Rodenburg et al, 2020;Wallace et al, 2020).…”

Biological Control of the Cucumber Downy Mildew Pathogen Pseudoperonospora cubensis

“…CDM severely affects the quality and yield of cucumber in all growing areas and results in significant economic losses [4][5][6][7][8]. CDM is distributed worldwide and occurs in both the seedling and adult plant stages of cucumber [9][10][11][12][13]. When the cucumber plant is infected by P. cubensis, the upper side of the leaf surface exhibits yellowish-brown lesions with irregular form, and gray sporangium layers appear on the lower side of the leaf surface under high humidity.…”

Development of an ecological strategy for the control of downy mildew (Pseudoperonospora cubensis) in cucumber cultivation (Cucumis sativus L.)

“…The disease cause premature defoliation and then the sunburn of the fruit due to overexposure to direct sunlight. In the United States, host resistance in past decades successfully controlled the downy mildew; however, the pathogen has overcome this resistance and now has become a very severe threat to cucumber growers, mainly because it is also evolving fungicide resistance 8 . In Ecuador, the disease severely affects cucumber production damaging more than 60% of the output 7,9 .…”