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McHenry DJ, Aćimović SG. New Species-Specific Real-Time PCR Assays for Colletotrichum Species Causing Bitter Rot of Apple. Microorganisms 2024; 12:878. [PMID: 38792708 PMCID: PMC11123832 DOI: 10.3390/microorganisms12050878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024] Open
Abstract
Bitter rot of apple is an economically important worldwide disease caused by different Colletotrichum species, depending on many factors such as climate, geography, other hosts, and crop management practices. Culture, morphology, and single-locus sequencing-based methods for identifying the Colletotrichum species are severely limited in effectiveness, while the multilocus sequence typing methods available for delineating species are costly, time-intensive, and require high expertise. We developed species-specific hydrolysis probe real-time PCR assays for the following nine Colletotrichum species causing bitter rot in the Mid-Atlantic U.S.A.: C. fructicola, C. chrysophilum, C. noveboracense, C. gloeosporioides s.s., C. henanense, C. siamense and C. theobromicola from the C. gloeosporioides species complex, and C. fioriniae and C. nymphaeae from the C. acutatum species complex. After searching 14 gene regions, we designed primers and probes in 5 of them for the nine target species. Four primer-probe set pairs were able to be duplexed. Sensitivity tests showed as little as 0.5 pg DNA were detectable. These real-time PCR assays will provide rapid and reliable identification of these key Colletotrichum species and will be critically important for studies aiming to elucidate their biology, epidemiology, and management on apples as the number one produced and consumed tree fruit in the U.S.A.
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Affiliation(s)
| | - Srđan G. Aćimović
- Plant Pathology Laboratory, Alson H. Smith Jr. Agricultural Research and Extension Center, School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Winchester, VA 22602, USA
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Emanuel IB, Laird AE, Hand FP. Understanding Environmental and Physiological Factors Affecting the Biology of Diaporthe ilicicola, the Fungus Causing Latent Fruit Rot in Winterberry. PLANT DISEASE 2023; 107:2986-2996. [PMID: 36856642 DOI: 10.1094/pdis-11-22-2759-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Fruit rot in winterberry is associated with a complex of fungal pathogens. Among them, Diaporthe ilicicola plays a unique role by infecting flowers at bloom, resulting in symptom development in mature fruit. This research aimed to identify at what stage of maturation Ilex fruit can develop disease symptoms and correlate changes in fruit physiology (sugar and phenolic content) and environment (temperature and light intensity) with disease incidence. Correlation data informed in vitro studies testing the ability of putative factors to alter growth of D. ilicicola and select opportunistic fungi within the fruit rot complex: Alternaria alternata, Colletotrichum fioriniae, and Epicoccum nigrum. Results indicated that Ilex fruit do not develop symptoms until 81 to 108 days after inoculation. Temperature and fruit phenolic content were negatively correlated with disease incidence, while fruit sugar concentration and light intensity were positively correlated. In vitro assays revealed that sugar concentration had no effect on the growth of D. ilicicola, but increased light intensity increased hyphal growth and pycnidium formation. Additionally, phenolics extracted from fruit inhibited spore germination in A. alternata, induced secondary conidiation in C. fioriniae, and late season phenolic extracts increased hyphal melanization and pycnidial formation in D. ilicicola. Finally, drops in field temperatures, when replicated in vitro, resulted in a decrease in hyphal growth and spore germination for all fungi. These results suggest that changes in Ilex fruit phenolics during maturation and the increased exposure to light following defoliation may play a role in symptom development by altering D. ilicicola growth within the fruit.
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Affiliation(s)
- Isabel B Emanuel
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43201
| | - Aleacia E Laird
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43201
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Feng L, Zhang Y, Chen W, Mao B. Colletotrichum siamense Strain LVY 9 Causing Spot Anthracnose on Winterberry Holly in China. Microorganisms 2023; 11:microorganisms11040976. [PMID: 37110399 PMCID: PMC10146105 DOI: 10.3390/microorganisms11040976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/30/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Winterberry holly (Ilex verticillata) is an economically valuable landscaping ornamental plant. Serious outbreaks have been reported, in its leaf tips curl upward, irregular black brown spots appear on leaves, and extensive defoliation is commonly observed. The incidence in Hangzhou was estimated at 50% and resulted in large economic losses for growers in 2018. Samples were collected from the main cultivation area in Zhejiang Province. In total, 11 fungal isolates were obtained from diseased leaves through a single-spore purification method, and isolate LVY 9 exhibited strong pathogenicity. Based on morphology and molecular phylogenetic analyses based on multilocus sequence typing of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), internal transcribed spacer (ITS) regions, actin (ACT), calmodulin (CAL), and chitin synthase (CHS-1) genes, we identified the pathogen as Colletotrichum siamense, causative agent of anthracnose of winterberry holly.
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Affiliation(s)
- Lin Feng
- Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yahui Zhang
- Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Weiliang Chen
- Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Bizeng Mao
- Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou 310058, China
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Liu L, Li X, Guo W, Shi J, Chen W, Lei Y, Ma Y, Dai H. MdWRKY120 Enhance Apple Susceptibility to Alternaria alternata. PLANTS (BASEL, SWITZERLAND) 2022; 11:3389. [PMID: 36501429 PMCID: PMC10004717 DOI: 10.3390/plants11233389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Alternaria alternata (A. alternata) is a common pathogen that greatly influences apples' quantity and quality. However, chemical treatments produce increased health risks along with decreased food and environmental safety. Advancements in plant molecular biology, such as transgenic technology, have increased apple trees' resistance to pathogens and have therefore attracted widespread attention. WRKY transcription factors are involved in abiotic and biotic stress regulation; however, their biological role in non-model plants such as apple, is still unknown. In this investigation, MdWRKY120 was isolated from the 'GL-3' apple to determine its function during Alternaria alternate infection. The MdWRKY120-GFP fusion protein was located in the nucleus. MdWRKY120 in yeast cells exhibited activating transcriptional activity, meaning it is a transcription activator. MdWRKY120 overexpression transgenic plants were more sensitive to A. alternata, while RNAi transgenic plants showed increased resistance to A. alternata. This investigation demonstrates that MdWRKY120 enhances the susceptibility of apples to A. alternata.
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Affiliation(s)
- Lifu Liu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- School of Horticulture, Liaoning Vocational College of Ecological Engineering, Shenyang 110101, China
| | - Xiaoming Li
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Wei Guo
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Jiajun Shi
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Wenjun Chen
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Yingying Lei
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Yue Ma
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Hongyan Dai
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
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Prasannath K, Galea VJ, Akinsanmi OA. Sources, Detection, and Inoculum Quantification of Flower Blight Pathogens in Macadamia. PHYTOPATHOLOGY 2022; 112:2151-2158. [PMID: 35585722 DOI: 10.1094/phyto-08-21-0365-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladosporium spp., and gray mold caused by Botrytis spp., collectively known as flower blight cause significant yield losses in macadamia. Potential sources of inoculum of the various pathogens in macadamia tree canopy were examined using pathogenicity tests and a multiplex quantitative PCR (qPCR) assay developed in this study. The qPCR assay detected and quantified the relative abundance of the inoculum of flower blight pathogens. The assay revealed that remnant racemes contributed a high amount of inoculum of all the three groups of flower blight pathogens, while the yellow halo leaf spot contributed only Pestalotiopsis/Neopestalotiopsis species. The amount of conidia per gram of remnant racemes ranged from 7 × 103 to 2 × 104 for dry flower disease, 3 × 103 to 1 × 104 for green mold, and 5 to 8 × 103 for gray mold pathogens. Conidia of Pestalotiopsis/Neopestalotiopsis species quantified from leaf spots varied from 1 × 102 to 1 × 103 per cm2. Pathogenicity tests performed on developing racemes under field conditions, using conidial suspensions from both sources of inoculum (remnant racemes and yellow halo leaf spot), resulted in severe flower bight symptoms. Disease severity was not significantly different (P > 0.05) when remnant racemes were incubated directly with the developing racemes compared with inoculation with conidial suspension from the material. This suggests that racemes from preceding seasons that remain in the tree canopy carryover inoculum between seasons and should be removed as a control option for flower blights in macadamia orchards.
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Affiliation(s)
- Kandeeparoopan Prasannath
- The University of Queensland, Queensland Alliance for Agriculture & Food Innovation, Centre for Horticultural Science, Dutton Park, QLD 4102, Australia
| | - Victor J Galea
- The University of Queensland, School of Agriculture & Food Sciences, Gatton, QLD 4343, Australia
| | - Olufemi A Akinsanmi
- The University of Queensland, Queensland Alliance for Agriculture & Food Innovation, Centre for Horticultural Science, Dutton Park, QLD 4102, Australia
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Martin PL, Peter KA. Quantification of Colletotrichum fioriniae in Orchards and Deciduous Forests Indicates It Is Primarily a Leaf Endophyte. PHYTOPATHOLOGY 2021; 111:333-344. [PMID: 32729787 DOI: 10.1094/phyto-05-20-0157-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colletotrichum fioriniae of the C. acutatum species complex is an important hemibiotrophic pathogen of vegetables and fruits in temperate regions worldwide. In apple, it is one of the primary species responsible for bitter rot disease. Understanding the disease cycle is complicated because many broadleaf plants can be hosts of C. fioriniae. By detecting and quantifying rain-splashed C. acutatum species complex conidia in more than 500 samples from heavily bitter-rot-infected apple orchards and nearby forested woodlots over two summers, we show that conidial quantities were higher in the woodlots than in the orchards. Testing of more than 1,000 surface-disinfected leaves of apple and 24 different forest plant species showed that overall C. fioriniae was an abundant leaf endophyte, with high variation in leaf colonization area. Endophytic isolates from leaves were pathogenic on apples, and multilocus sequence analysis showed 100% identity between most isolates from leaves and diseased fruits. Apple leaves endophytically infected with C. fioriniae were present in a conventionally managed orchard and abundant in an untreated orchard. These lines of evidence, in the context of previously published research, lead us to hypothesize that the main ecological role of C. fioriniae is that of a leaf endophyte, which we present as a generalized C. fioriniae infection cycle that provides an updated framework for its integrated management in agricultural systems.
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Affiliation(s)
- Phillip L Martin
- Department of Plant Pathology and Environmental Microbiology, Fruit Research and Extension Center, The Pennsylvania State University, Biglerville, PA 17307
| | - Kari A Peter
- Department of Plant Pathology and Environmental Microbiology, Fruit Research and Extension Center, The Pennsylvania State University, Biglerville, PA 17307
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