Temperature and Humidity Regulate Sporulation of Corynespora cassiicola That Is Associated with Pathogenicity in Cucumber (Cucumis sativus L.)

Simple Summary Cucumber is an important vegetable crop for mankind. Cucumber target leaf spot, caused by Corynespora cassiicola, is a worldwide disease. The disease is commonly treated with fungicides, but due to the emergence of resistance, the efficacy of fungicides has declined. At present, control of this disease has been problematic. Spores of C. cassiicola play a significant role in the epidemiology of the disease. Owing to this, fungus cultivation is necessary to properly understand its life cycle as well as pathogenesis for the possible future development of an efficient and environmentally friendly control method. Therefore, in this study, different temperatures and moistures were evaluated on four substrates to see their impact on the sporulation of C. cassiicola. Furthermore, the relationship between spore size and pathogenicity was determined. The results showed that temperature and moisture affected not only spore production, but also spore size. In addition, spore size was found to be an important virulence determinant in C. cassiicola. Abstract Cucumber target leaf spot, caused by Corynespora cassiicola, is an emerging disease with a high incidence that causes severe damage to cucumbers on a global scale. Therefore, efforts need to be undertaken to limit the spread and infection of this pathogen, preferably by using environmentally friendly methods. In this study, the effects of temperature and moisture on the sporulation of C. cassiicola were investigated in vitro and in vivo. The novelty of our study refers to the observation of spore production and size as well as the revelation of a correlation between spore size and virulence. On potato dextrose agar (PDA) and cucumber−leaf extract agar (CEA), temperature played a critical role in spore production, which was strongly influenced by both temperature and moisture on detached leaves and cucumber seedlings. Maximum spore production was found at 30 °C on PDA and 25 °C on CEA, cucumber detached leaves and living plants. Lower spore productions were observed with a stepwise change of 5 °C. In addition, the largest spore production was found at 100% relative humidity (RH) in comparison to the other tested moisture. Moreover, moisture was found to be the most important factor affecting spore size, accounting for 83.09–84.86% of the total variance in length and 44.72–73.10% of the total variance in width. The longest−narrowest spores were formed at 100% RH, and the shortest−widest spores were formed at 75% RH. Furthermore, the result showed that larger spores of C. cassiicola were more virulent and small spores were avirulent. Our findings will contribute to the development of new strategies for the effective alleviation and control of cucumber target leaf spot.

[1]  V. Garre,et al.  Heterotrimeric G-alpha subunits Gpa11 and Gpa12 define a transduction pathway that control spore size and virulence in Mucor circinelloides , 2019, PloS one.

[2]  N. Cui,et al.  Functional Identification of Corynespora cassiicola-Responsive miRNAs and Their Targets in Cucumber , 2019, Front. Plant Sci..

[3]  Hope A. Gruszewski,et al.  Vortex-induced dispersal of a plant pathogen by raindrop impact , 2019, Proceedings of the National Academy of Sciences.

[4]  Xin‐Gen Zhou,et al.  Plant-Based Culture Media for Improved Growth and Sporulation of Cercospora janseana. , 2019, Plant disease.

[5]  Xiang-li Dong,et al.  Effects of temperature, moisture and nutrition on conidial germination, survival, colonization and sporulation of Trichothecium roseum , 2018, European Journal of Plant Pathology.

[6]  N. Cui,et al.  Transcriptome and miRNA analyses of the response to Corynespora cassiicola in cucumber , 2018, Scientific Reports.

[7]  W. Xiao,et al.  A Role for the Respiratory Chain in Regulating Meiosis Initiation in Saccharomyces cerevisiae , 2018, Genetics.

[8]  Chen Lihe,et al.  Identification and biological characteristics of Corynespora cassiicola causing leaf spot on Sanchezia nobilis. , 2018 .

[9]  A. Clement,et al.  Effect of Drying Temperature on Nutritional Content of Moringa Oleifera Leave , 2017 .

[10]  Dong Liu,et al.  Expression and functional analysis of the transcription factor-encoding Gene CsERF004 in cucumber during Pseudoperonospora cubensis and Corynespora cassiicola infection , 2017, BMC Plant Biology.

[11]  J. Heilmann‐Clausen,et al.  Mean spore size and shape in ectomycorrhizal and saprotrophic assemblages show strong responses under resource constraints , 2017 .

[12]  Su Mei Yew,et al.  Genomic insight into pathogenicity of dematiaceous fungus Corynespora cassiicola , 2017, PeerJ.

[13]  Xiang-li Dong,et al.  Effects of Temperature and Moisture on Sporulation and Infection by Pseudoperonospora cubensis. , 2017, Plant disease.

[14]  S. Ying,et al.  Effect of vacuolar ATPase subunit H (VmaH) on cellular pH, asexual cycle, stress tolerance and virulence in Beauveria bassiana. , 2017, Fungal genetics and biology : FG & B.

[15]  V. Rossi,et al.  Environmental effects on the production of Botrytis cinerea conidia on different media, grape bunch trash, and mature berries , 2016 .

[16]  Kyu Rang Kim,et al.  Effects of Interrupted Wetness Periods on Conidial Germination, Germ Tube Elongation and Infection Periods of Botryosphaeria dothidea Causing Apple White Rot , 2016, The plant pathology journal.

[17]  R. Ahir,et al.  Effect of temperature, relative humidity and pH on mycelial growth and sporulation of Fusarium solani causing root rot of Indian Aloe (Aloe barbadensis Mill.). , 2013 .

[18]  N. Magan,et al.  Comparison of temperature and moisture requirements for sporulation of Aspergillus flavus sclerotia on natural and artificial substrates. , 2012, Fungal biology.

[19]  N. Lalancette,et al.  Modeling sporulation of Fusicladium carpophilum on nectarine twig lesions: relative humidity and temperature effects. , 2012, Phytopathology.

[20]  Liang Bao-ju.  Research Progress on Cucumber Target Leaf Spot(Corynespora cassiicola) , 2012 .

[21]  J. Heitman,et al.  Sporangiospore Size Dimorphism Is Linked to Virulence of Mucor circinelloides , 2011, PLoS pathogens.

[22]  T. Miyamoto,et al.  Distribution and molecular characterization of Corynespora cassiicola isolates resistant to boscalid , 2010 .

[23]  E. M. Reis,et al.  Effect of substrates, light and filter paper on Corynespora cassiicola sporulation , 2010 .

[24]  L. Dixon,et al.  Host specialization and phylogenetic diversity of Corynespora cassiicola. , 2009, Phytopathology.

[25]  J. Heitman,et al.  Spores as Infectious Propagules of Cryptococcus neoformans , 2009, Infection and Immunity.

[26]  A. Justesen,et al.  Rapid global spread of two aggressive strains of a wheat rust fungus , 2008, Molecular ecology.

[27]  R. Reuveni,et al.  Effect of humidity on epidemiological patterns of the powdery mildew (sphaerotheca fuliginea) on squash , 1974, Phytoparasitica.

[28]  T. Sugiyama,et al.  Molecular Characterization and Diagnosis of QoI Resistance in Cucumber and Eggplant Fungal Pathogens. , 2007, Phytopathology.

[29]  Zhang Changhua,et al.  Effects of temperature on growth, sporification, and germination of flue-cured tobacco leaf spot causing C. cassiicola in Guizhou province , 2006 .

[30]  W. Fry,et al.  Temperature and Leaf Wetness Requirements for Pathogen Establishment, Incubation Period, and Sporulation of Phytophthora infestans on Petunia × hybrida. , 2005, Plant disease.

[31]  K. Phelps,et al.  Development of MILIONCAST, an Improved Model for Predicting Downy Mildew Sporulation on Onions. , 2004, Plant disease.

[32]  R. Durbin,et al.  Increasing sporulation of corynespora cassiicola , 1975, Mycopathologia.

[33]  K. Chee.  Studies on Sporulation , Pathogenicity and Epidemiology of Corynespora cassiicola on Hevea Rubber , 2004 .

[34]  Song Xiao-dong.  Comparative studies on the morphology of Sphaeropsis sapinea spores and mycelia , 2004 .

[35]  N. Lalancette,et al.  Quantitative Models for Describing Temperature and Moisture Effects on Sporulation of Phomopsis amygdali on Peach. , 2003, Phytopathology.

[36]  M. Kwon,et al.  Occurrence of target leaf spot disease caused by Corynespora cassicola on cucumber in Korea , 2003 .

[37]  James K. M. Brown,et al.  Aerial Dispersal of Pathogens on the Global and Continental Scales and Its Impact on Plant Disease , 2002, Science.

[38]  M. Thomas,et al.  Effects of temperature and relative humidity on sporulation of Metarhizium anisopliae var. acridum in mycosed cadavers of Schistocerca gregaria. , 2001, Journal of invertebrate pathology.

[39]  R. Spotts,et al.  Disease Incidence-Inoculum Dose Relationships for Botrytis cinerea and Penicillium expansum and Decay of Pear Fruit Using Dry, Airborne Conidia. , 2001, Plant disease.

[40]  R. Kennedy,et al.  A New Method To Monitor Airborne Inoculum of the Fungal Plant Pathogens Mycosphaerella brassicicola andBotrytis cinerea , 2000, Applied and Environmental Microbiology.

[41]  L. L. Wilson,et al.  Effects of Temperature on Sporulation and Latent Period of Colletotrichum Spp. Infecting Strawberry Fruit. , 1997, Plant disease.

[42]  C. H. Lee,et al.  Relationship between disease occurrence and dispersal of airborne conidia of Corynespora cassiicola on sesame in field. , 1990 .

[43]  P. Walklate,et al.  The Role of Rain in Dispersal of Pathogen Inoculum , 1989 .

[44]  J. E. Lawrence.  Environmental Effects on the Development and Dissemination ofCladosporium carpophilumon Peach , 1982 .

[45]  M. Castro.  Leaf blight caused by Corynespora [cassiicola]: a new disease on cucumber (Cucumis sativus) in the Valley of culiacan, Sinaloa, Mexico and its chemical control , 1979 .

[46]  E. Bashi,et al.  Host and Environmental Influences on Sporulation In Vivo , 1978 .

[47]  J. Rotem,et al.  Effects of temperature, leaf wetness, leaf bacteria and leaf and bacterial diffusates on production and lysis of Rhynchosporium secalis spores☆ , 1976 .

[48]  J. Manners,et al.  Environmental effects on the quantity and viability of conidia produced by Erysiphe graminis , 1974 .

[49]  A. Lang.  Osmotic coefficients and water potentials of sodium chloride solutions from 0 to 40°C , 1967 .

[50]  D. Meredith.  Violent Spore Release in Some Fungi Imperfecti , 1963 .

[51]  P. Winston,et al.  Saturated Solutions For the Control of Humidity in Biological Research , 1960 .

[52]  C. Wei.  Notes on Corynespora. , 1950 .

[53]  H. Barnett,et al.  Sporulation of Colletotrichum lindemuthianum in culture. , 1950 .

[54]  M. A. Curtis,et al.  Fungi Cubenses (Hymenomycetes). , 1868 .