1
|
Newberry EA, Babu B, Roberts PD, Dufault NS, Goss EM, Jones JB, Paret ML. Molecular Epidemiology of Pseudomonas syringae pv. syringae Causing Bacterial Leaf Spot of Watermelon and Squash in Florida. Plant Dis 2018; 102:511-518. [PMID: 30673490 DOI: 10.1094/pdis-07-17-1002-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
From 2013 to 2014, bacterial leaf spot epidemics incited by Pseudomonas syringae pv. syringae affected an estimated 3,000 ha of watermelon and squash in Florida, and caused foliar blighting and transplant losses in severely affected fields. To investigate the diversity of the causal agent, we isolated 28 P. syringae strains from diseased plants grown in 10 Florida and Georgia counties over the course of 2 years. Strains were confirmed as P. syringae through sequence analysis of the 16S ribosomal RNA, phenotypic, and biochemical profiling; however, 20 displayed an atypical phenotype by exhibiting nonfluorescent activity on King's medium B agar and being negative for ice-nucleating activity. Multilocus sequence analysis and BOX polymerase chain reaction revealed the presence of two haplotypes among the collected strains that grouped into two distinct clades within P. syringae phylogroup 2. Pathogenicity testing showed that watermelon, cantaloupe, and squash seedlings were susceptible to a majority of these strains. Although both haplotypes were equally virulent on cantaloupe, they differed in virulence on watermelon and squash. The distribution of one haplotype in 9 of 10 Florida and Georgia counties sampled indicated that these epidemics were associated with the recent introduction of a novel clonal P. syringae lineage throughout major watermelon production areas in Florida.
Collapse
Affiliation(s)
- E A Newberry
- North Florida Research and Education Center, University of Florida, Quincy
| | - B Babu
- North Florida Research and Education Center, University of Florida, Quincy
| | - P D Roberts
- Southwest Florida Research and Education Center, University of Florida, Immokalee
| | - N S Dufault
- Department of Plant Pathology, University of Florida, Gainesville
| | - E M Goss
- Department of Plant Pathology, University of Florida, Gainesville
| | - J B Jones
- Department of Plant Pathology, University of Florida, Gainesville
| | - M L Paret
- North Florida Research and Education Center, University of Florida, Quincy
| |
Collapse
|
2
|
Baltrus DA, McCann HC, Guttman DS. Evolution, genomics and epidemiology of Pseudomonas syringae: Challenges in Bacterial Molecular Plant Pathology. Mol Plant Pathol 2017; 18:152-168. [PMID: 27798954 PMCID: PMC6638251 DOI: 10.1111/mpp.12506] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 05/12/2023]
Abstract
A remarkable shift in our understanding of plant-pathogenic bacteria is underway. Until recently, nearly all research on phytopathogenic bacteria was focused on a small number of model strains, which provided a deep, but narrow, perspective on plant-microbe interactions. Advances in genome sequencing technologies have changed this by enabling the incorporation of much greater diversity into comparative and functional research. We are now moving beyond a typological understanding of a select collection of strains to a more generalized appreciation of the breadth and scope of plant-microbe interactions. The study of natural populations and evolution has particularly benefited from the expansion of genomic data. We are beginning to have a much deeper understanding of the natural genetic diversity, niche breadth, ecological constraints and defining characteristics of phytopathogenic species. Given this expanding genomic and ecological knowledge, we believe the time is ripe to evaluate what we know about the evolutionary dynamics of plant pathogens.
Collapse
Affiliation(s)
| | - Honour C. McCann
- New Zealand Institute for Advanced StudyMassey UniversityAuckland 0632New Zealand
| | - David S. Guttman
- Department of Cell and Systems BiologyUniversity of TorontoTorontoON M5S 3B2Canada
- Centre for the Analysis of Genome Evolution and FunctionUniversity of TorontoTorontoON M5S 3B2Canada
| |
Collapse
|
3
|
Newberry EA, Jardini TM, Rubio I, Roberts PD, Babu B, Koike ST, Bouzar H, Goss EM, Jones JB, Bull CT, Paret ML. Angular Leaf Spot of Cucurbits is Associated With Genetically Diverse Pseudomonas syringae Strains. Plant Dis 2016; 100:1397-1404. [PMID: 30686200 DOI: 10.1094/pdis-11-15-1332-re] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Angular leaf spot of cucurbits is generally considered to be caused by Pseudomonas syringae pv. lachrymans. It has a worldwide distribution and has been observed to emerge sporadically under humid and wet conditions. Reports of multiple P. syringae pathovars associated with the disease and lack of molecular analysis has left the true diversity of populations in the United States unclear. In this study, we collected 27 P. syringae strains causing foliar lesions and blighting on watermelon, cantaloupe, and squash in Florida, Georgia, and California over several years. Strains were fluorescent on King's medium B agar and displayed the typical phenotypic and biochemical characteristics of P. syringae. P. syringae pv. lachrymans is a member of genomospecies 2. However, the genetic profiles obtained through both MLSA (gyrB, rpoD, gapA, and gltA) and BOX-PCR (BOXA1R) identified 26 of the P. syringae strains to be distributed among three clades within genomospecies 1, and phylogenetically distinct from genomospecies 2 member P. syringae pv. lachrymans. A novel MLSA haplotype of the pathogen common to all states and cucurbit hosts was identified. Considerable genetic diversity among P. syringae strains infecting cucurbits is associated with the same disease, and reflects the larger ecological diversity of P. syringae populations from genomospecies 1.
Collapse
Affiliation(s)
- E A Newberry
- North Florida Research & Education Center, University of Florida, Quincy, FL
| | | | - I Rubio
- USDA-ARS, Salinas, CA; and Undergraduate Research Opportunities Center, Seaside, California State University, Monterey Bay, CA
| | - P D Roberts
- Southwest Florida Research and Education Center, University of Florida, Immokalee, FL
| | - B Babu
- North Florida Research & Education Center, University of Florida, Quincy, FL
| | - S T Koike
- University of California Cooperative Extension, Monterey County, Salinas, CA
| | - H Bouzar
- Sakata Seed America, Inc., Salinas, CA
| | - E M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | - J B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | - C T Bull
- USDA-ARS, Salinas, CA (current address: Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA)
| | - M L Paret
- North Florida Research & Education Center, University of Florida, Quincy, FL
| |
Collapse
|