First Report of Dollar Spot of Seashore Paspalum (Paspalum vaginatum) Caused by Sclerotinia homoeocarpa in South China

Seashore paspalum (Paspalum vaginatum Swartz), a warm-season perennial grass, is native to tropical and subtropical regions of North and South America (1). Its fine texture and tolerance to low mowing and hypersaline environments make it a commercially promising turfgrass species for coastal regions of south China. In late March 2009, disease symptoms were observed from two golf course fairways in Shenzhen and Foshan, Guangdong Province, China. Small, round patches from 25 to 75 mm in diameter were found to be consisting of bleached, straw color leaf lesions bounded by reddish brown margins. Similar patches had previously been observed on seashore paspalum since 1997 in Guangdong Province, but this turf species has been grown in southern China only since the early 1990s. These symptoms were observed when daytime temperatures were above 25°C and with heavy dew formation at night. Greatest severity was seen in the spring and fall. Several contact and systemic fungicides were applied after first symptoms were observed and they were usually successful in suppressing disease. To confirm the disease as dollar spot, isolates from Shenzhen and Foshan were obtained by plating diseased leaf blades of P. vaginatum (cv. Salam) on potato dextrose agar media. Isolates produced white, fluffy, aerial mycelium, columnar when mature, and usually with a cinnamon base and dark brown or black substratal stroma on and in the agar. One representative isolate from each location was chosen for pathogenicity testing. Six-week-old P. vaginatum (cv. Salam) grown from seed in pots was inoculated, with 5-mm-diameter agar plugs with hyphae from 5-day-old cultures, by direct placement onto leaves and with three replicate pots per isolate. Plants treated with sterile agar plugs served as controls. Inoculated turf was incubated at 25°C with 12-h light/dark conditions. A plastic film was also placed over the pots to retain moisture. Chlorotic leaf lesions started to develop 4 days after inoculation and became a bleached straw color. The same fluffy, white fungus was reisolated from lesions, while no disease was observed on controls, thus completing Koch's postulates. The internal transcribed spacer (ITS) region of the ribosomal DNA was amplified from DNA extracted from two isolates using primers ITS5 and ITS4 (2), and the 610-bp sequences showed 98% similarity with Sclerotinia homoeocarpa F.T. Bennett in GenBank and have been deposited as Accessions GQ386985 and GU002301. Dollar spot on P. vaginatum has been commonly observed in the United States (1). To our knowledge, this is the first confirmed report of dollar spot on P. vaginatum in China or from any host plant in China. References: (1) R. R. Duncan and R. N. Carrow. Seashore Paspalum: The Environmental Turfgrass. John Wiley and Sons, Toronto, ON, Canada. 2000. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press Inc., New York, 1990.

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Genetic Diversity of Sclerotinia homoeocarpa Isolates from Turfgrasses from Various Regions in North America

Plant Disease ◽

10.1094/pdis.2004.88.11.1269 ◽

2004 ◽

Vol 88 (11) ◽

pp. 1269-1276 ◽

Cited By ~ 19

Author(s):

G. Viji ◽

W. Uddin ◽

N. R. O'Neill ◽

S. Mischke ◽

J. A. Saunders

Keyword(s):

United States ◽

Genetic Diversity ◽

Creeping Bentgrass ◽

The United States ◽

Vegetative Compatibility ◽

Major Group ◽

Golf Courses ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Geographical Regions

Sixty-seven isolates of Sclerotinia homoeocarpa, causing dollar spot disease in creeping bentgrass, annual bluegrass, Bermudagrass, and perennial ryegrass turf, collected from 23 golf courses in various geographical regions of the United States and Canada between 1972 and 2001, were characterized by vegetative compatibility, genetic diversity, and pathogenicity. Eleven vegetative compatibility groups (VCGs A to K) were identified among the isolates tested in this study, and five of them (VCGs G to K) were new. VCG B was the most predominant group, typifying 33 isolates (51%) tested. S. homoeocarpa isolates collected from golf courses in Pennsylvania belonged to seven VCGs (A, B, E, F, G, I, and K), whereas three groups were observed in those collected from New York (B, E, and G) and New Jersey (E, H, and I). Two isolates, one each from Pennsylvania and Canada, were incompatible when paired with the tester isolates in all possible combinations, and did not fall into any known VCG. An isolate collected from Canada was compatible with tester isolates from two VCGs (C and D). Genetic analyses using amplified fragment length polymorphism (AFLP) showed the presence of two genetically distinct groups, designated as major group and the minor group. The major group included 36 isolates collected from various golf courses in the United States and Canada. Two isolates collected from bermudagrass in Florida formed a separate cluster, the minor group. Isolates that belonged to the major group were further divided into two subgroups (1 and 2). Subgroup 1 consisted of all the isolates that belonged to VCGs A, E, G, H, and I. Three of the four isolates that belonged to VCG K also were clustered with isolates of subgroup 1. Subgroup 2 consisted of all the isolates from VCG B, and one each from VCGs F and K. Pathogenicity assays on Penncross creeping bentgrass showed significant differences (P = 0.05) in virulence among the isolates. Overall, a relationship between virulence and VCGs was observed, in which certain virulence groups corresponded to specific VCGs; however, such a relationship was not observed between virulence and AFLPs. Close similarity among isolates of S. homoeocarpa collected from different locations in the United States and Canada suggests that isolates of the same genotype could be involved in outbreaks of dollar spot epidemics at multiple locations.

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First Report of Dollar Spot of Buffalograss Caused by Sclerotinia homoeocarpa in Oklahoma

Plant Disease ◽

10.1094/pdis-92-8-1249b ◽

2008 ◽

Vol 92 (8) ◽

pp. 1249-1249 ◽

Cited By ~ 2

Author(s):

S. M. Marek ◽

I. R. Moncrief ◽

N. R. Walker

Keyword(s):

Warm Season ◽

Its Region ◽

The United States ◽

Small Subunit ◽

Its Sequences ◽

Type I ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

First Report ◽

Warm Season Grass

Buffalograss (Buchloe dactyloides (Nutt.) Engelm.) is a perennial, warm-season grass native to the central plains of North America and a dominant plant over much of the shortgrass prairie ecosystem. Its prostrate growth habit and excellent drought tolerance make it a commercially promising turfgrass species, and numerous turf-type cultivars have been released. In the spring of 2007, the southern plains states experienced prolonged periods of excessive precipitation during which numerous buffalograss swards throughout north-central Oklahoma exhibited symptoms of dollar spot (1). A fungus morphologically identical to Sclerotinia homoeocarpa Bennett was consistently isolated from diseased buffalograss leaves collected from three locations in Oklahoma, two from Payne County and one from Logan County. Thirty-day-old seedlings of B. dactyloides (‘Cody’ and ‘Topgun’) and Agrostis stolonifera (‘SR1020’) were inoculated by placing potato dextrose agar (PDA) plugs, colonized by mycelia of each S. homoeocarpa isolate, onto the seedlings' leaves. Sterile PDA plugs were placed on plants as controls. Leaf lesions developed after 4 days only on inoculated plants, and S. homoeocarpa was reisolated from lesions, satisfying Koch's postulates. The nuclear ribosomal internal transcribed spacer (ITS) region was amplified from DNA extracted from cultures of the three buffalograss isolates and a bentgrass isolate using primers ITS4 and ITS5 (2) and sequenced. Sequences were similar to one another (97 to 99% identical), however, two isolates shared a 420-bp, type I intron in the 18S small subunit rDNA. A search of GenBank at NCBI found the ITS sequences were most similar to the ITS regions of other S. homoeocarpa accessions (97% identical). The ITS sequences from the four isolates were deposited in GenBank (Accession Nos. EU123800–EU123803). To our knowledge, this is the first report of dollar spot on a native, warm-season grass in the United States and the disease appears to be endemic to buffalograss in Oklahoma and Kansas (N. A. Tisserat, personal communication). References: (1) R. W. Smiley et al. Page 22 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press Inc., New York, 1990.

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Evaluation of a Sclerotinia homoeocarpa Population with Multiple Fungicide Resistance Phenotypes Under Differing Selection Pressures

Plant Disease ◽

10.1094/pdis-06-18-1080-re ◽

2019 ◽

Vol 103 (4) ◽

pp. 685-690 ◽

Cited By ~ 3

Author(s):

Hyunkyu Sang ◽

James T. Popko ◽

Geunhwa Jung

Keyword(s):

Fungicide Resistance ◽

The United States ◽

Golf Courses ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Selection Pressures ◽

Effective Strategies ◽

Benzimidazole Resistance ◽

Dicarboximide Resistance

Dollar spot, caused by Sclerotinia homoeocarpa, is one of the most significant diseases of cool-season turfgrass on golf courses. Resistance to the benzimidazole, dicarboximide, and succinate dehydrogenase inhibitor (SDHI) classes and reduced sensitivity to the sterol-demethylation inhibitor (DMI) in S. homoeocarpa populations have been widely reported in the United States. Moreover, the occurrence of S. homoeocarpa populations with multiple fungicide resistance (MFR) is a growing problem on golf courses. The present study was undertaken to evaluate the efficacy of DMI, dicarboximide, and SDHI against a S. homoeocarpa population with MFR on a Connecticut golf course fairway from 2014 to 2016. Also, because the S. homoeocarpa population consisted of four different phenotypes with differing resistance profiles to benzimidazole, dicarboximide, and DMI, in vitro sensitivity assays were used to understand the dynamics of the MFR population in the presence and absence of fungicide selection pressures. Results indicated that boscalid fungicide (SDHI) was able to provide an acceptable control of the MFR dollar spot population. Propiconazole or iprodione application selected isolates with both DMI and dicarboximide resistance (DMI-R/Dicar-R). In the absence of fungicide selection pressures, the percent frequency of DMI-R/Dicar-R or DMI and benzimidazole resistance (DMI-R/Ben-R) isolates declined in the population. Out of the four phenotypes, the percent frequency of isolates with DMI, dicarboximide, and benzimidazole resistance (DMI-R/Dicar-R/Ben-R) was the lowest in the population regardless of fungicide selection pressures. Our first report of MFR population dynamics will help develop effective strategies for managing MFR and potentially delay the emergence of future resistant populations in S. homoeocarpa.

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Genetic relationships and variation among ecotypes of seashore paspalum (Paspalum vaginatum) determined by random amplified polymorphic DNA markers

Genome ◽

10.1139/g94-143 ◽

1994 ◽

Vol 37 (6) ◽

pp. 1011-1017 ◽

Cited By ~ 37

Author(s):

Zhao-Wei Liu ◽

Robert L. Jarret ◽

Ronny R. Duncan ◽

Stephen Kresovich

Keyword(s):

Rapd Markers ◽

Genetic Relationships ◽

Random Amplified Polymorphic Dna ◽

The United States ◽

Principal Coordinates Analysis ◽

Data Set ◽

Seashore Paspalum ◽

Principal Coordinates ◽

Paspalum Vaginatum ◽

High Level

Random amplified polymorphic DNA (RAPD) markers were used to assess genetic relationships and variation among ecotypes of the turfgrass seashore paspalum (Paspalum vaginatum Swartz). Vegetative tissues or seeds of 46 seashore paspalum ecotypes were obtained from various locations in the United States, Argentina, and South Africa. Leaf DNA extracts were screened for RAPD markers using 34 10-mer random primers. A total of 195 reproducible RAPD fragments were observed, with an average of six fragments per primer. One hundred and sixty-nine fragments (87% of the total observed) were polymorphic, among which 27 fragments (16%) were present in three or less ecotypes, indicating the occurrence of a high level of genetic variation among the examined accessions of this species. Cluster analysis (UPGMA) and principal coordinates analysis were performed on the RAPD data set. The results illustrate genetic relationships among the 46 ecotypes, and between ecotypes and their geographical origins. Ecotypes from southern Africa could be differentiated from the U.S. and most of the Argentinean ecotypes. With a few exceptions, ecotypes collected from Argentina, Hawaii, Florida, and Texas were separated into distinct clusters.Key words: RAPDs, polymerase chain reaction, genetic diversity, phenetic analysis.

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Endophyte-Mediated Suppression of Dollar Spot Disease in Fine Fescues

Plant Disease ◽

10.1094/pd-90-0994 ◽

2006 ◽

Vol 90 (8) ◽

pp. 994-998 ◽

Cited By ~ 106

Author(s):

Bruce B. Clarke ◽

James F. White ◽

Richard H. Hurley ◽

Mónica S. Torres ◽

S. Sun ◽

...

Keyword(s):

Close Association ◽

The United States ◽

Field Trials ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Red Fescue ◽

Epichloë Festucae ◽

Extensive Field ◽

Wide Range ◽

Fine Fescue

In 1989, a close association was found between single-plant progenies of strong creeping red fescue infected with the endophyte Epichloë festucae and enhanced suppression of dollar spot, a widespread foliar disease of turfgrass caused by Sclerotinia homoeocarpa. From this limited observation, extensive field evaluations were conducted on a wide range of fine fescue germplasm obtained throughout the United States and Europe to determine the frequency and magnitude of this association. In five field trials established between 1985 and 1991, endophyte-infected Chewings, hard, blue, and strong creeping red fescue cultivars, selections, and crosses consistently exhibited endophyte-mediated suppression of dollar spot, when compared with closely related endophyte-free entries. Endophyte-infected Chewings and hard fescue cultivars and selections also had greater turf density and supported less foliar mycelium of S. homoeocarpa than endophyte-free entries.

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First Report of Dollar Spot Caused by Sclerotinia homoeocarpa on Switchgrass in the United States

Plant Disease ◽

10.1094/pdis-04-11-0332 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1585-1585 ◽

Cited By ~ 2

Author(s):

A. L. Vu ◽

K. D. Gwinn ◽

B. H. Ownley

Keyword(s):

Panicum Virgatum ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Leading Edge ◽

The United States ◽

Small Subunit ◽

Grass Species ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

Leaf Spots

Sclerotinia homoeocarpa causes dollar spot on many grass species; however, it has not been described on switchgrass (Panicum virgatum L.) as a host. In August 2010, bleached, tan-to-straw-colored leaf spots with dark brown-to-reddish brown margins were found in patchy distribution in small field plots of ‘Alamo’ switchgrass at the East Tennessee Research and Education Center, Knoxville, TN. The plots had been planted to switchgrass for the past 21 years. Disease lesions covered 75 to 80% of leaf tissue per patch and were also evident on stems. To identify the pathogen, center portions of diseased leaves were cut into 20- to 30-cm segments, surface disinfested (95% ethanol for 30 s, 10% bleach for 1 min, and 95% ethanol for 30 s), and dried. Disinfested leaves (5-cm sections that included a leading edge of a lesion) were plated on potato dextrose agar (PDA). Plates were incubated at 22°C. Within 12 h, white, fluffy, aerial mycelium developed. Viewed from above, colonies were tan to cinnamon in color with a dark brown-to-black substratal stroma on and in the agar, which appeared brown as viewed from below the petri dish. No spores were observed. Morphological characteristics of colony and hyphal growth were identical to those of S. homoeocarpa F.T. Bennett (1). Pathogenicity studies were conducted with 6-week-old ‘Alamo’ switchgrass grown from scarified (2), surface-disinfested seed. Nine (9 × 9-cm2) pots with 18 plants each were inoculated with 20 mycelial plugs (6-mm diameter) per pot, taken from 3-to-5-day-old fungal cultures. Two control pots were inoculated with sterile PDA plugs and subjected to the same conditions. Plugs were placed on leaf surfaces and around the plant crowns. Plants were subjected to high humidity by enclosure in a plastic bag and incubated in a growth chamber at 25/20°C with a 12-h photoperiod. Plastic bags were removed after 48 h. Leaf spots appeared as early as 2 days postinoculation, with full symptoms after 2 weeks for eight of nine replicates. Control plants had no symptoms. The fungus was cultured from leaf spots and stem lesions of inoculated plants as described above. The same disease and fungus were observed, completing Koch's postulates. The internal transcribed spacer (ITS) regions of ribosomal DNA from the original isolate used for inoculation and from the isolate recovered from plants in the pathogenicity assay were amplified with PCR with primers ITS4 and ITS5 (4). PCR amplicons of ~565 bp were sequenced; sequences of amplicons from the original isolate and reisolate were identical and submitted to GenBank (Accession No. HQ850151). The sequence had 99% homology with several S. homoeocarpa isolates in GenBank, including three isolates from buffalograss in Oklahoma (Accession Nos. EU123800, EU123802, and EU123803). The mitochondrial small subunit region was amplified from the original isolate with primers NMS1 and NMS2 (3). The resultant 536-bp fragment was sequenced and submitted to GenBank (Accession No. HQ850152), but no S. homoeocarpa sequences were available for comparison. To our knowledge, this is the first confirmed report of switchgrass as a natural host for S. homoeocarpa, extending the known host range for the pathogen. References: (1) F. T. Bennett. Ann. Appl. Biol. 24:236, 1937. (2) K. D. Gwinn et al. Crop Sci. 31:1369, 1991. (3) K. N. Li et al. Appl. Environ. Microbiol. 60:4324, 1994. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, NY, 1990.

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Comparative transcriptome profiling provides insights into plant salt tolerance in seashore paspalum (Paspalum vaginatum)

10.21203/rs.2.11244/v3 ◽

2020 ◽

Author(s):

Peipei Wu ◽

Steven Cogill ◽

Yijian Qiu ◽

Zhigang Li ◽

Man Zhou ◽

...

Keyword(s):

Transcription Factors ◽

Salt Stress ◽

Salinity Tolerance ◽

Molecular Mechanisms ◽

Perennial Grass ◽

Differential Expression Analysis ◽

Reduction Process ◽

Salt Treatment ◽

Seashore Paspalum ◽

Paspalum Vaginatum

Abstract Background: Seashore paspalum (Paspalum vaginatum), a halophytic warm-seasoned perennial grass, is tolerant of many environmental stresses, especially salt stress. To investigate molecular mechanisms underlying salinity tolerance in seashore paspalum, physiological characteristics and global transcription profiles of highly (Supreme) and moderately (Parish) salinity-tolerant cultivars under normal and salt stressed conditions were analyzed.Results: Physiological characterization comparing highly (Supreme) and moderately (Parish) salinity-tolerant cultivars revealed that Supreme’s higher salinity tolerance is associated with higher Na+ and Ca2+ accumulation under normal conditions and further increase of Na+ under salt-treated conditions (400 mM NaCl), possibly by vacuolar sequestration. Moreover, K+ retention under salt treatment occurs in both cultivars, suggesting that it may be a conserved mechanism for prevention of Na+ toxicity. We sequenced the transcriptome of the two cultivars under both normal and salt-treated conditions (400 mM NaCl) using RNA-seq. De novo assembly of about 153 million high-quality reads and identification of Open Reading Frames (ORFs) uncovered a total of 82,608 non-redundant unigenes, of which 3,250 genes were identified as transcription factors (TFs). Gene Ontology (GO) annotation revealed the presence of genes involved in diverse cellular processes in seashore paspalum’s transcriptome. Differential expression analysis identified a total of 828 and 2,222 genes that are responsive to high salinity for Supreme and Parish, respectively. “Oxidation-reduction process” and “nucleic acid binding” are significantly enriched GOs among differentially expressed genes in both cultivars under salt treatment. Interestingly, compared to Parish, a number of salt stress induced transcription factors are enriched and show higher abundance in Supreme under normal conditions, possibly due to enhanced Ca2+ signaling transduction out of Na+ accumulation, which may be another contributor to Supreme’s higher salinity tolerance.Conclusion: Physiological and genomics analyses of seashore paspalum reveal major molecular underpinnings contributing to plant response to salt stress in this halophytic warm-seasoned perennial grass. The data obtained provide valuable molecular resources for functional studies and developing strategies to engineer plant salinity tolerance.

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Comparative transcriptome profiling provides insights into plant salt tolerance in seashore paspalum (Paspalum vaginatum)

10.21203/rs.2.11244/v2 ◽

2019 ◽

Author(s):

Peipei Wu ◽

Steven Cogill ◽

Yijian Qiu ◽

Zhigang Li ◽

Man Zhou ◽

...

Keyword(s):

Transcription Factors ◽

Salt Stress ◽

Salinity Tolerance ◽

Molecular Mechanisms ◽

Perennial Grass ◽

Differential Expression Analysis ◽

Reduction Process ◽

Salt Treatment ◽

Seashore Paspalum ◽

Paspalum Vaginatum

Abstract Background: Seashore paspalum (Paspalum vaginatum), a halophytic warm-seasoned perennial grass, is tolerant of many environmental stresses, especially salt stress. To investigate molecular mechanisms underlying salinity tolerance in seashore paspalum, physiological characteristics and global transcription profiles of highly (Supreme) and moderately (Parish) salinity-tolerant cultivars under normal and salt stressed conditions were analyzed. Results: Physiological characterization comparing highly (Supreme) and moderately (Parish) salinity-tolerant cultivars revealed that Supreme’s higher salinity tolerance is associated with higher Na+ and Ca2+ accumulation under normal conditions and further increase of Na+ under salt-treated conditions (400 mM NaCl), possibly by vacuolar sequestration. Moreover, K+ retention under salt treatment occurs in both cultivars, suggesting that it may be a conserved mechanism for prevention of Na+ toxicity. We sequenced the transcriptome of the two cultivars under both normal and salt-treated conditions (400 mM NaCl) using RNA-seq. De novo assembly of about 153 million high-quality reads and identification of Open Reading Frames (ORFs) uncovered a total of 82,608 non-redundant unigenes, of which 3,250 genes were identified as transcription factors (TFs). Gene Ontology (GO) annotation revealed the presence of genes involved in diverse cellular processes in seashore paspalum’s transcriptome. Differential expression analysis identified a total of 828 and 2,222 genes that are responsive to high salinity for Supreme and Parish, respectively. “Oxidation-reduction process” and “nucleic acid binding” are significantly enriched GOs among differentially expressed genes in both cultivars under salt treatment. Interestingly, compared to Parish, a number of salt stress induced transcription factors are enriched and show higher abundance in Supreme under normal conditions, possibly due to enhanced Ca2+ signaling transduction out of Na+ accumulation, which may be another contributor to Supreme’s higher salinity tolerance. Conclusion: Physiological and genomics analyses of seashore paspalum reveal major molecular underpinnings contributing to plant response to salt stress in this halophytic warm-seasoned perennial grass. The data obtained provide valuable molecular resources for functional studies and developing strategies to engineer plant salinity tolerance.

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Comparative transcriptome profiling provides insights into plant salt tolerance in seashore paspalum (Paspalum vaginatum)

10.21203/rs.2.11244/v1 ◽

2019 ◽

Author(s):

Hong Luo ◽

Peipei Wu ◽

Steven Cogill ◽

Yijian Qiu ◽

Zhigang Li ◽

...

Keyword(s):

Transcription Factors ◽

Salt Stress ◽

Salinity Tolerance ◽

Molecular Mechanisms ◽

De Novo ◽

Perennial Grass ◽

Differential Expression Analysis ◽

Reduction Process ◽

Seashore Paspalum ◽

Paspalum Vaginatum

Abstract Background Seashore paspalum (Paspalum vaginatum), a halophytic warm-seasoned perennial grass, is tolerant of many environmental stresses, especially salt stress. To investigate molecular mechanisms underlying salinity tolerance in seashore paspalum, physiological characteristics and global transcription profiles of highly (Supreme) and moderately (Parish) salinity-tolerant cultivars under normal and salt stressed conditions were analyzed. Results Physiological characterization comparing highly (Supreme) and moderately (Parish) salinity-tolerant cultivars revealed that Supreme’s higher salinity tolerance is associated with higher Na+ and Ca2+ accumulation under normal conditions and further increase of Na+ under salt-treated conditions (400 mM NaCl), possibly by vacuolar sequestration. Moreover, K+ retention under salt treatment occurs in both cultivars, suggesting that it may be a conserved mechanism for prevention of Na+ toxicity. We sequenced the transcriptome of the two cultivars under both normal and salt-treated conditions (400 mM NaCl) using RNA-seq. De novo assembly of about 153 million high-quality reads and identification of Open Reading Frames (ORFs) uncovered a total of 82,608 non-redundant unigenes, of which 3,250 genes were identified as transcription factors (TFs). Gene Ontology (GO) annotation revealed the presence of genes involved in diverse cellular processes in seashore paspalum’s transcriptome. Differential expression analysis identified a total of 828 and 2,222 genes that are responsive to high salinity for Supreme and Parish, respectively. GO enrichment analysis demonstrated that genes involved in “oxidation-reduction process” and “nucleic acid binding” are significantly associated with salinity tolerance in both cultivars. Interestingly, compared to Parish, a number of salt stress induced transcription factors are enriched and show higher abundance in Supreme under normal conditions, possibly due to enhanced Ca2+ signaling transduction out of Na+ accumulation, which may be another contributor to Supreme’s higher salinity tolerance. Conclusion Physiological and genomics analyses of seashore paspalum reveal major molecular underpinnings contributing to plant response to salt stress in this halophytic warm-seasoned perennial grass. The data obtained provide valuable molecular resources for functional studies and developing strategies to engineer plant salinity tolerance.

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First Report of Laetisaria fuciformis Causing Red Thread on Seashore Paspalum (Paspalum vaginatum) in South China

Plant Disease ◽

10.1094/pdis-01-12-0053-pdn ◽

2012 ◽

Vol 96 (9) ◽

pp. 1374-1374 ◽

Cited By ~ 2

Author(s):

W. Zhang ◽

Z. B. Nan ◽

G. D. Liu

Keyword(s):

Southern China ◽

Warm Season ◽

Fungal Growth ◽

Small Subunit ◽

Golf Course ◽

Golf Courses ◽

Seashore Paspalum ◽

First Report ◽

Paspalum Vaginatum ◽

Plastic Bag

Seashore paspalum (Paspalum vaginatum Swartz.) is a prostrate-growing, perennial, warm-season turfgrass native to tropical and coastal areas (2). Because of its good texture and natural tolerance to various environmental stresses, seashore paspalum has been introduced to golf courses in coastal regions of southern China. In April 2010, circular or irregular pink patches ranging from 5 to 50 cm in diameter were observed in the golf course fairway and rough established with cv. Salam on two golf courses in Haikou, Hainan Province, China. When morning dew was present or rainfall occurred, a pink layer of gelatinous fungal growth could be observed on leaves and sheaths. The green leaves of infected plants initially became water soaked, then tan to bleached, shriveled, and infested with pink or reddish, gelatinous, stranded hyphae. The hyphae matted together, then formed threadlike or antlerlike stromata from the tips of blighted leaves. Two isolates from each golf course were collected by plating diseased leaf blades, stromata, or hyphal aggregates from the blighted leaves directly onto antibiotic (0.01% gentamicin sulfate) amended potato dextrose agar. To confirm pathogenicity, isolates were inoculated on 6-week-old P. vaginatum (cv. Seaspray) planted (0.5 mg seed/cm–2) in 10-cm pots. Inoculum was prepared by culturing isolates separately on an autoclaved mixture of 100 g of rye grain and 20 ml of water for 3 weeks at 25°C. Pots were inoculated by placing 2 g of infected grain within the center of the turf canopy or 2 g of sterilized, uninfested grains to serve as controls, with four replications of each treatment. After inoculation, each pot was placed in a translucent plastic bag and placed into a greenhouse at 24 ± 2°C with a 12-h photoperiod (1). Two days after inoculation, the fungus was observed on the leaves. Approximately 40% of leaves in inoculated pots were necrotic after 7 days, and this increased to 80% after 21 days. Diseased plants in inoculated pots displayed symptoms similar to those observed in the field and no symptoms were detected on the control plants. The two isolates were successfully reisolated from all symptomatic tissues, completing Koch's postulates. Sequences of mitochondrial small subunit ribosomal RNA (mt-SSU) were amplified from the two isolates by primers MS1 and MS2, and the sequences showed 99% similarity with Laetisaria fuciformis from the NCBI database (Accession No. AY293232). Red thread on turfgrass has been commonly observed in temperate climates during periods of cool and humid weather (3). To our knowledge, this is the first report of L. fuciformis causing red thread on P. vaginatum or from any host plant in China. References: (1) L. L. Burpee and L. G. Goulty. Phytopathology. 74:692, 1984. (2) R. R. Duncan and R. N. Carrow. Seashore Paspalum: The Environmental Turfgrass. John Wiley and Sons, Toronto, ON, Canada, 2000. (3) R. W. Smiley et al. Page 38 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005.

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