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1.
Animal ; 15(7): 100244, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34175575

RESUMO

In some lower rainfall regions of the world (300-750 mm), common vetch (Vicia sativa L., hereafter referred to as vetch) has been shown to have yields competitive with alternate crops and provide high-quality hay for ruminant diets, but there are few studies of vetch performance as a livestock feed, or of vetch varietal differences in livestock feeding value. This study evaluated vetch varietal differences in hay nutritive value, ruminal fermentation properties, nutrient digestibility, nitrogen retention and animal performance in fattening lambs consuming a diet comprising 20% vetch. Fifty male Hu lambs with an initial BW of 17.7 ± 0.27 kg and 2-3 months of age were assigned randomly into five groups of 10 lambs, and each allocated one of five dietary treatments for 67 days (10 days of adaptation and a 57 day experimental period). All diets contained 30% maize stover, 50% concentrate, and with a different forage source (on an as-fed basis): 20% alfalfa hay (Control), 20% vetch 333A (C333A) hay, 20% vetch Lanjian No. 1 (CLJ1) hay, 20% vetch Lanjian No. 2 (CLJ2) hay, or 20% vetch Lanjian No. 3 (CLJ3) hay. Hay CLJ3 had greater contents of ash, CP, ether extract, in vitro organic matter digestibility and metabolizable energy, and lower cell wall contents (P < 0.05) than those of C333A and CLJ1 hays, but similar to the CLJ2 hay (P > 0.05). Compared to the Control diet, the CLJ2 and CLJ3 diets resulted in greater (P < 0.05) final BW, average daily gain, total tract apparent digestibility of CP and NDF, and nitrogen balance, both when expressed as g/day and relative to nitrogen intake, while animal performance when fed diets with C333A or CLJ1 diet did not differ (P > 0.05) from the Control diet. No differences (P > 0.05) were observed between dietary treatments with respect to average daily feed intake, ruminal pH, total volatile fatty acid contents and molar proportions of acetate, butyrate, valerate, isobutyrate, and isovalerate, or total tract apparent digestibility of DM, organic matter, and ADF. The feed efficiency of tested feeds ranked CLJ3 = CLJ2 > CLJ1 > Control with C333A intermediate between CLJ1 and Control. In summary, considering hay quality, nutrient digestibility and animal weight gain, performance as a ruminant feed of hays from recently released vetch cultivars Lanjian No. 2 and Lanjian No. 3 was superior to the older cultivar C333A and the alfalfa control.


Assuntos
Vicia sativa , Ração Animal/análise , Animais , Dieta/veterinária , Digestão , Fermentação , Masculino , Nutrientes , Valor Nutritivo , Rúmen/metabolismo , Ovinos , Carneiro Doméstico
2.
Phytopathology ; 109(4): 593-606, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30307801

RESUMO

Rust (Melampsora apocyni) on Apocynum venetum is the major constraint to the commercial development of this medicinal herb. To determine the factors influencing rust intensity (maximum disease index [DImax]), rust was investigated from 2011 to 2015 in both cultivated and wild A. venetum plants. Partial least squares path modeling (PLS-PM) was used to analyze the paths and extent of the factors related to pathogen, environment, and host that affect rust intensity. DImax exhibited considerable variations across years and study sites, with variations linked to various factors fostering disease development. PLS-PM explained 80.0 and 70.1% of variations in DImax in cultivated and wild plants, respectively. Precipitation was the key factor determining DImax in both cultivated and wild plants (path coefficient [PC] = 0.313 and 0.544, respectively). In addition, the topsoil water content in cultivated plants and the total vegetation coverage in wild plants were also critical determinants of DImax via their effects on the microclimatic factor (contribution coefficients [CC] = 0.681 and 0.989, respectively; PC = 0.831 and 0.231, respectively). In both cultivated and wild plants, host factors were mainly dominated by A. venetum density (CC = 0.989 and 0.894, respectively), and their effect on DImax via the microclimatic factor (PC = 0.841 and 0.862, respectively) exceeded that via the inoculum factor (PC = 0.705 and 0.130, respectively). However, the indirect effects led to DImax variation, while the dilution effect on host (CC = 0.154) from weed in wild plants led to the indirect effect size in wild plants of 0.200, which was lower than -0.699 in cultivated plants.


Assuntos
Apocynum , Basidiomycota , Chuva , Apocynum/crescimento & desenvolvimento , Basidiomycota/patogenicidade , China , Doenças das Plantas , Chuva/microbiologia
3.
J Anim Physiol Anim Nutr (Berl) ; 101(5): 807-823, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28066943

RESUMO

The objective of this review was to systematically evaluate common vetch seeds as a potential feedstuff for animals, by summarizing and discussing the available published literature covering their nutritional composition as well as their content of antinutritional factors and potential techniques for their reduction. In addition, animal feeding studies that have investigated the effect of inclusion of common vetch seeds on animal growth and performance were identified and evaluated to stimulate interest in their use as a good source of nutrients for inclusion in animal diets. The collective literature shows that common vetch seeds are a less costly (in comparison with alternatives) and rich source of protein and minerals for farmed animals, are of high digestibility and have a high energy content, and can be used to partially or totally replace soya bean meal and/or to replace a large proportion of cereals in the diet. Furthermore, the literature shows that common vetch seeds contain a range of antinutritional factors which, if they are to be utilized in non-ruminant diets and to increase their utilizing efficiency, need to be removed or inactivated. This can be achieved via certain pre-processing methods, the combination of which may deliver better results.


Assuntos
Ração Animal/análise , Valor Nutritivo , Vicia sativa/fisiologia , Animais , Análise de Alimentos
4.
Genet Mol Res ; 14(4): 16987-99, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26681046

RESUMO

The relationship between disturbance, biodiversity, and ecosystem function has been a hot topic recently in international ecological research, and a universally applicable model remains elusive. In this study, we assessed the diversity and structure of a bacterial community in grassland soils along a disturbance gradient due to sheep grazing. Bacteria were identified based on 16S rDNA gene libraries prepared from a 12-year field experiment that included four grazing, intensity treatments: no grazing, light grazing, moderate grazing and heavy grazing in the Loess Plateau of northwestern China. We found that diversity indices of bacterial 16S rDNA increased with grazing intensity, suggesting that disturbance led to higher bacterial diversity. The bacterial community structure, measured as species composition, was also affected by grazing. In addition, the change in soil bacterial community composition was maximum under heavy grazing, based on the Sorensen similarity index. Overall, the relationship between disturbance and bacterial diversity is complex, therefore, more studies are required to determine the possibility of using microbial diversity as an indicator of ecosystem stability.


Assuntos
Bactérias/classificação , Biodiversidade , Ecossistema , Herbivoria , Ovinos , Microbiologia do Solo , Animais , Bactérias/genética , China , Biblioteca Gênica , Filogenia , RNA Ribossômico 16S/genética
5.
Genet Mol Res ; 14(4): 12228-39, 2015 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-26505371

RESUMO

Elymus L. is often planted in temperate and subtropical regions as forage. Species in the genus have 5 allopolyploid genomes that are found in the grass tribe Triticeae. To determine the phylogenetic relationships in Elymus species from western China, we estimated phylogenetic trees using sequences from the nuclear ribosomal internal transcribed spacer and non-coding chloroplast DNA sequences from 56 accessions (871 samples) of 9 polyploid Elymus species and 42 accessions from GenBank. Tetraploid and hexaploid Elymus species from western China had independent origins, and Elymus species from the same area or neighboring geographic regions were the most closely related. Based on the phylogenetic tree topology, the St- and Y-genomes were not derived from the same donor and Y-genome likely originated from the H-genome of Hordeum species, or they shared the same origin or underwent introgression. The maternal genome of tetraploid and hexaploid Elymus species originated from species of Hordeum or Pseudoroegneria. Additionally, Elymus species in western China began diverging 17-8.5 million years ago, during a period of increased aridification as a consequence of the Messinian salinity crisis. Elymus species adapted to drought and high salinity may have developed based on the environmental conditions during this period. Elymus evolution in western China may have been affected by the uplift of the Qinghai-Tibetan Plateau (5 million years ago), when Elymus seeds were dispersed by gravity or wind into a newly heterogeneous habitat, resulting in isolation.


Assuntos
Elymus/classificação , Elymus/genética , Filogenia , China , Evolução Molecular , Análise de Sequência de DNA
6.
Genet Mol Res ; 14(4): 17463-71, 2015 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-26782389

RESUMO

Epichloë endophytes are widely distributed mutualists of cool-season grasses and can protect their hosts against biotic and abiotic stresses. Previous studies have shown that Epichloë endophytes are specific to their grass hosts in tall Festuca and Lolium species. However, no systematic analysis exists of host specificity of asexual Epichloë endophytes and Chinese Elymus species. We analyzed the phylogenetic relationships between Chinese Elymus species and their diploid donor Hordeum species, using their corresponding Epichloë endophyte sequences. We found that 1) the maternal donor of the Chinese Elymus species was the Chinese Pseudoroegneria (St genome) or Hordeum (H genome); and 2) Chinese Hordeum species probably contained two species of Epichloë endophytes. One Epichloë endophyte was also present in a North American Elymus species. The other Epichloë endophyte was found in a Chinese Elymus species. Our results indicate that Epichloë endophytes isolated from Elymus species did not show grass-host specificity. 3) Plant hybridization could probably transform endophyte-free plants (E-) to endophyte-infected plants (E+). Based on our data, we formulate hypotheses about which Epichloë endophytes were spread via plant hybridization.


Assuntos
Endófitos/genética , Epichloe/genética , Filogenia , Simbiose/genética , Hordeum/genética , Lolium/genética , Especificidade da Espécie
7.
Lett Appl Microbiol ; 60(4): 372-8, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25511534

RESUMO

UNLABELLED: Embellisia astragali is an important seedborne pathogenic fungus responsible for yellow stunt and root rot of standing milk vetch (Astragalus adsurgens). The current detection methods that are based on culture and morphological identification are time-consuming, laborious and not always reliable. A PCR-based diagnostic method was developed with the species-specific primer pairs AatpF and AatpR designed from the sequence of the plasma membrane ATPase gene of E. astragali. The specificity of the primers was verified by PCR analysis of DNA from three strains of E. astragali and 19 isolates of nontarget fungi from other genera. A single 135-bp amplicon was detected only from E. astragali isolates, and no cross-reactions were observed with any other tested isolates. The detection limit of this new method was 5 pg of template DNA. The specific primers enabled the detection of E. astragali from the seed of standing milk vetch. This species-specific PCR method provides quick, simple, powerful and reliable detection of E. astragali. SIGNIFICANCE AND IMPACT OF THE STUDY: PCR-based detection is fast, convenient, precise and sensitive compared to the traditional methods of pathogen detection. This study develops the first PCR method for the detection of Embellisia astragali in standing milk vetch seeds. The species-specific primer set designed from the plasma membrane ATPase gene of E. astragali can detect the pathogen. This assay could be applied in the standing milk vetch seed industry.


Assuntos
Adenosina Trifosfatases/genética , Ascomicetos/genética , Astrágalo/microbiologia , Doenças das Plantas/microbiologia , Sementes/microbiologia , Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Sequência de Bases , Primers do DNA , DNA Fúngico/genética , Dados de Sequência Molecular , Técnicas de Tipagem Micológica/métodos , Raízes de Plantas/microbiologia , Reação em Cadeia da Polimerase/métodos , Sensibilidade e Especificidade , Alinhamento de Sequência
8.
Plant Dis ; 98(10): 1436, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30703946

RESUMO

Waitea circinata var. zeae was previously reported as the causal agent of leaf and sheath spot on Festuca arundinacea (1) and Panicum tennesseense (2) in the United States. In late May to mid-September 2013, a disease resembling leaf and sheath spot was observed on Paspalum vaginatum in fairways from several golf courses in Hainan Province, China. Affected plants initially had large yellow and brown spots on leaves and sheathes, then the whole plant turned yellowish-brown and eventually died. The same symptoms were also observed on a lawn established with Zoysia tenuifolia in Hainan University. Symptomatic leaves were surface sterilized in 1% hypochlorite for 1 min, rinsed with sterile water three times, and plated onto potato dextrose agar (PDA) amended with 0.01% gentamicin sulfate. Two Rhizoctonia-like fungal isolates were obtained from the diseased P. vaginatum (Isolate no. ML-WC1) and Z. tenuifolia (Isolate no. HNU-1) samples. After incubation on PDA for 1 week at 25°C, white mycelial colonies developed and eventually turned a salmon color with age. Small, white, spherical sclerotia (0.5 to 1 mm in diameter) were observed submerged throughout the agar media after incubation for 1 week and turned a reddish-brown color within 4 weeks. The two isolates were tentatively identified as W. circinata var. zeae based on these characteristics. The internal transcribed spacer (ITS) region of the ribosomal DNA gene was amplified and sequenced using primer pair ITS1/ITS4. The sequences of the two isolates (GenBank Accession Nos. KJ717943 and KJ717944) were more than 99% similar to W. circinata var. zeae (JQ688056 and JQ688059) sequences deposited in GenBank. To confirm pathogenicity, inocula were prepared by incubating autoclaved rye grains with strains ML-WC1 and HNU-1 for 2 weeks at 25°C. Ten colonized rye grains were uniformly spread around the crowns of 6-week-old P. vaginatum and Z. tenuifolia seedlings grown in 10-cm-diameter pots. Each isolate was placed in four separate pots and four control plants were treated with non-inoculated grain. All pots were covered with translucent plastic bags and placed in a greenhouse at 24 ± 2°C with a 12-h light/dark cycle. By 1 week post-inoculation, significant blighting of leaves and sheaths was observed, while non-inoculated plants showed no symptoms. W. circinata var. zeae was successfully re-isolated from symptomatic plants and confirmed by its Rhizoctonia-like mycelium and small, reddish-brown, spherical sclerotia on the PDA. Recently a related species, W. circinata var. circinata, causing brown ring patch on two cool-season grasses was reported in China (3). However, the isolates of W. circinata var. zeae were distinguished from W. circinata var. circinata base on ITS sequence data and morphological characters. To our knowledge, this is the first report of W. circinata var. zeae infecting P. vaginatum and Z. tenuifolia in China. References: (1) S. S. Martin, Jr. and L. T. Lucas. Plant Dis. 67:676, 1983. (2) N. A. Mitkowski. Plant Dis. 87:1006, 2003. (3) X. X. Ni et al. Plant Dis. 96:12, 2012.

9.
Plant Dis ; 98(10): 1429, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30704000

RESUMO

The species of Apocynum venetum and Poacynum pictum grow widely from the middle to northwestern regions of China. During the summers of 2011 to 2013, a spot blight was found in wild and cultivated both species in Altay Prefecture of the Xinjiang Uygur Autonomous Region, China. The spot blight caused leaf yellowing and leaf drop, and serious damage to plant phloem. Lesions were circular to irregular, and the diameter of lesions on A. venetum and P. pictum was 1.84 to 6.84 × 1.23 to 4.24 mm and 2.05 to 7.09 × 1.46 to 5.65 mm, respectively. Pycnidia were 70 to 115 × 52 to 120 µm, scattered, spherical, buried, and had a brown hard shell with a prominent ostiole. Conidia were colorless, needle-shaped, or linear. The conidia base was obtuse, containing 3 to 5 indistinct septa, 46.3 to 110.3 × 2 to 2.5 µm. Fungal cultures were obtained by cutting 1-cm-long infected leaf pieces from the margins of the lesions following routine surface sterilizing procedures. The sections were placed on potato dextrose agar (PDA) in petri dishes and incubated at 23°C for 4 weeks (4). Hyphae had septa, the aerial and base mycelium was white and rufous, and the back of the colony was sunken and cracked after 2 weeks, but no spore was observed. To verify the identity, total DNA was extracted directly from fungal mycelium with a UNIQ-10 fungal genomic DNA extraction kit (Sangon Biotech, Shanghai, China) and PCR amplification performed with primers ITS1/ITS4 (3). A 512-bp PCR product was sequenced and contrasted with GenBank sequences using BLAST, which revealed 99% identity with Septoria sp. (GenBank Accession No. KC134322.1). To confirm pathogenicity, A. venetum and P. pictum were planted in pots and grown in a greenhouse. After 6 weeks of growth, plants were inoculated by spraying a mycelial suspension onto the foliage while control plants received a similar application of sterilized distilled water. Five pots (3 plants per pot) were used for each treatment. The pots were then placed on plates filled with tap water and covered with Plexiglas hoods in the greenhouse at 20 to 25°C. Lesions began to appear 6 to 7 days after inoculation with the mycelial suspension, whereas control plants remained healthy. The average disease incidence was 19.3%. The symptoms and morphology were similar to Septoria apocyni in Teterevnikova (2). It was determined that spot blight of A. venetum and P. pictum was caused by S. apocyni based on morphological comparison. There is one relevant literature report of spot blight on A. venetum and P. pictum in China, but without any details of the pathogenicity or morphology of the pathogen (1). We believe that this is the first report of S. apocyni occurring on the species of A. venetum and P. pictum in China. References: (1) W. Sun et al. Special Economic Animal and Plant 8:23, 2005. (2) D. N. Teterevnikova. Page 79 in: Septoria sp. Fungus of USSR. Armenian Academy of Sciences Publishing, Armenia, USSR, 1987. (3) G. J. M. Verkley et al. Mycologia 96:558, 2004. (4) W. Zhang et al. Plant Dis. 96:1374, 2012.

10.
Plant Dis ; 97(4): 561, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30722241

RESUMO

Hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) is widely used on golf course putting greens in southern China. In September 2011, circular pink patches ranging from 10 to 20 cm in diameter were observed on putting greens established with cv. 'Tifgreen' on a golf course in Haikou, Hainan Province. There were approximately 50 pink patches on a putting green. Infected leaves were covered with pink, gelatinous fungal mycelium, which resulted in the production of chlorotic lesions. Lesions expanded, became water-soaked, and leaves died basipetally. A pink fungus, characterized by the presence of clamp connections, was consistently isolated from leaves of infected plants on a potato dextrose agar amended with 0.01% gentamicin sulfate. Based on morphological characteristics, the fungus was preliminary identified as Limonomyces roseipellis Stalpers & Loerakker, the causal agent of pink patch of turfgrass (2,3). To verify the identity, the internal transcribed spacer (ITS) of rDNA was amplified and sequenced using primers ITS1 and ITS4. Comparison with sequences in the GenBank database revealed that the ITS sequence (Accession No. KC193592) showed 98% homology with the sequence of L. roseipellis (EU622846). For pathogenicity tests, inoculum was prepared by culturing the fungus on an autoclaved mixture of 100 g of rye grain and 20 ml water for 3 weeks at 25°C. Six-week-old C. dactylon plants in 10-cm pots were inoculated by placing 2 g of infested grain in the center of the turf canopy, or 2 g sterilized, uninfested grain as a control, with four replications of each treatment. After inoculation, pots were covered with translucent plastic bags and placed in a greenhouse at 24 ± 2°C with a 12-h photoperiod (1). After 3 weeks, more than 70% of leaves in the infested pots showed symptoms identical to those observed under natural conditions while control plants remained asymptomatic. The fungus was reisolated from symptomatic plants. To our knowledge, this is the first report of L. roseipellis causing pink patch on hybrid bermudagrass in China. References: (1) L. L. Burpee and L. G. Goulty. Phytopathology 74:692, 1986. (2) J. D. Kaplan and N. Jackson. Plant Dis. 67:159, 1983. (3) J. A. Stalpers and W. M. Loerakker. Can. J. Bot. 60:529, 1982.

11.
Plant Dis ; 96(3): 454, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30727103

RESUMO

Medicago sativa L. is one of the most important perennial forage crops and has been cultivated for more than 2,000 years in China. A previously unreported sprout wilt disease of M. sativa, affecting as much as 25% of the seedlings, was observed in northwest China (Gansu Province) in March 2011. First symptoms on the sprouts were dehydration and yellowing. Within 24 to 48 h, the sprouts stopped growing, wilted, turned brown, and bacteria began oozing from the material. Three symptomatic sprout samples collected from a grower with the wilt problem were processed for microbiological analysis. Bacteria isolated from symptomatic samples produced a pink, diffusible pigment in King's medium B and nutrient agar supplemented with glucose, sucrose, and maltose. The three isolates were negative for gram stain reaction, oxidase, production of hydrogen sulfide and indole, growth in KCN broth, arginine dihydrolase activity, hydrolysis of casein, hydrolysis of gelatin, and acid production from L-arabinose, dulcitol, glycerol, lyxose, and starch. In contrast, they were positive for catalase, nitrate reduction, Voges-Proskauer, hydrolysis of aesculin, acid production from D-ribose, maltose and sucrose, assimilation of adonitol, L-lactate, mannitol, Myo-inositol, erythritol, sorbitol, and sucrose, and growth in 5% NaCl at 36°C. The 16S rDNA of three isolates (Cp1, Cp2, and Cp3) was amplified using the 7F (5'-CAGAGTTTGATCCTGGCT-3') and 1540R (5'-AGGAGGTGATCCAGCCGCA-3') primers. The sequences for the 1,428-bp amplicon from the isolates were identical (GenBank Accession No. JN900058) and had 99% sequence identity with 16S rDNA of Erwinia persicinus strains (including the type strain LMG 11254 [GenBank Accession No. Z96086.1], GS 04 [GenBank Accession No. DQ365580.1], LPPA 373 [GenBank Accession No. AJ937837.1], LPPA 408 [GenBank Accession No. AM294946.1], LMG 2691 [GenBank Accession No. AJ001190.1], and HK 204 [GenBank Accession No. NR_026049.1]). The three isolates were also evaluated in pathogenicity tests. Bacterial suspensions (108 CFU/ml) were spray inoculated on 7-day-old M. sativa sprouts of cv. Algonquin. The inoculated sprouts were placed onto 2% water agar in petri dishes (five sprouts per 9-cm dish) with four dishes for each bacterial isolate and control. The dishes were sealed with Parafilm for 2 days and held in an incubator at 25°C with a 12-h photoperiod. Assays were repeated twice. Symptoms that developed within 7 days were similar to those originally observed, whereas symptoms did not occur on control sprouts sprayed with sterile distilled water. Bacteria sharing the characteristics of the inoculated isolates were recovered from symptomatic sprouts, hence fulfilling Koch's postulates. E. persicinus has been isolated previously from Phaseolus vulgaris (1), Pisum sativum (2), tomato, banana, and cucumber (3). To our knowledge, this is the first report of E. persicinus from M. sativa. References: (1) A. J. González et al. Plant Dis. 89:109, 2005. (2) A. J. González et al. Plant Dis. 91:460, 2007. (3) M. V. Hao et al. Int. J. Syst. Bacteriol. 40:379, 1990.

12.
Plant Dis ; 96(9): 1374, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30727150

RESUMO

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.

13.
Plant Dis ; 93(6): 673, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30764429

RESUMO

Orchardgrass or cocksfoot (Dactylis glomerata L.) has been widely cultivated as a forage crop in many provinces of China (1). It is also a native perennial forage grass, which grows at the edge of forests, shrubs, and mountainous grasslands in Xinjiang and Sichuan (2). In September of 2007, signs of choke disease on orchardgrass were observed in a native grassland under birch woodland near Altai City, Xinjiang, China. Stromata, which formed on culms of diseased grass, enclosing the inflorescence and leaf sheath, were 4.5 to 5.5 mm long, smooth or wrinkled, white and later becoming yellowish or yellow, tuberculate, dry, and covered with perithecia. Inflorescences surrounded by fungal stromata were choked and failed to mature, thus restricting seed production. Pure cultures were obtained by directly scraping stromata from the surface and incubating it on antibiotic potato dextrose agar (PDA). The colonies were cottony, white on the upper surface, and white to yellow on the reverse. The growth rate was 13 to 21 mm per week at 25°C on PDA. Conidia were hyaline, lunate to reniform, and measured 4.1 ± 0.5 × 2.2 ± 0.5 µm. They accumulated in small globose heads at the tips of conidiogenous cells and were produced singly on conidiophores of 13 to 33 µm long and 2.7 to 4.1 µm wide at the base. Internal transcribed spacer (ITS) sequence by BLAST search had 99% similarity with an Epichloë typhina isolate of orchardgrass in Spain (GenBank Accession No. AM262420.1). Cultural characteristics, microscopic examination, and phylogenetic analysis showed that this choke disease on D. glomerata was caused by the fungus E. typhina (Pers.) Tul. & C. Tul. as described by White (4). To our knowledge, this is the first report of E. typhina causing choke disease on orchardgrass in China. The pathogen has been identified in France, England, Germany, Sweden, Switzerland, and the United States (3,4) with the same symptoms as those reported here. In 1997, choke disease was found in 70% of the fields in the Willamette Valley of Oregon, with disease incidences ranging from 0.05 to 28%. It was predicted to increase and spread under the prevailing climatic conditions (3). This new disease report is to provide observational and diagnostic information to help with recognition and prevention of disease spread in orchardgrass cultivation regions of China. References: (1) X. R. Chao et al. Shandong Agric. Sci. 1:7, 2005. (2) S. X. Jia, ed. China Forage Plant Flora. China Agriculture Press, Beijing, 1987. (3) W. F. Pfender and S. C. Alderman. Plant Dis. 83:754, 1999. (4) J. W. White. Mycologia 85:444, 1993.

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