Filamentous fungi quiescent in seeds and culm nodes of weedy and forage grass species endemic to the Palouse Region of Washington and Idaho

Asymptomatic seeds of forage and weedy grasses from germplasm accessions and from uncultivated sites in eastern Washington and western Idaho were assayed for the presence of quiescent filamentous fungi. Asymptomatic culm nodes of the same species were similarly assayed. The predominant taxa isolated were strains of dematiaceous hyphomycetes, principally strains of Alternaria and Cladosporium. A. infectoria was the species most frequently isolated from seed. A. tenuissima was common and A. alternata was rare. Aspergillus, Penicillium and Fusarium were very rare or absent in stored germplasm. Pathogenic coelomycetes were common in asymptomatic node samples, occasionally present in asymptomatic field seed, but were not detected in germplasm accessions. Previous reports of frequent occurrence of A. alternata in grass seed are probably the results of misidentification of various small-spored Alternarias, especially A. infectoria, as A. alternata.This revised version was published online in October 2005 with corrections to the Cover Date.     

Diversity within two serogroups of Rhizobium leguminosamm native to soils in the Palouse of eastern Washington*

The effect of plant genotype, soil temperature, and moisture on recovery of Rhizobium leguminosamm serogroups WA01 and WA02 from soil, was evaluated in the greenhouse using three plant genotypes (Pisum sativum cv. Alaska, Pisum sativum cv. Paloma and Lens culinaris cv. Rechief), three temperatures (12, 20 and 24°C) and soil from two different slope positions. The impact of moisture was followed by assessing pea nodulation after incubation of soil at different preplanting moisture levels. Isolates were also evaluated for serogroup, response to low levels of antibiotics and efficacy of symbiotic characters. Of the 33 antibiotic-strain combinations showing growth, 10 permitted 50% or more of the isolates to grow. Of the 24 clusters obtained, all except one were dominated by isolates in either serogroup. WA01 or WA02. There was no relation between either serogroup or cluster groupings and N₂ fixation. Serogroup recovery was influenced by plant genotype and temperature. At root temperatures of 12 and 24°C, serogroup WA02 occurred in a significantly lower fraction of the lentil nodules as compared to the pea species. At 12°C, recovery of WA02 was higher for the Paloma than Alaska pea. Recovery of WA02 in pea nodules generally increased as the soil moisture was preconditioned to drier levels of -0.5 and -1.5 MPa water potential.     

Fleshy fungi in grass fields. Dependence on fertilization, grass species, and age of field

An experimental field with grass had 48 squares which were treated with combinations of NPK fertilizers. The fungus flora was studied 1978–1980 by numerous yearly observations. A total of 40 species were noted: 36 agarics and 4 gasteromycetes. 24 species were confined to squares where nitrate was applied. 5 of these species were recorded as fairy ring formers. The fairy rings developed exclusively in the +N squares. Some common species grew in both +N and –N squares, while a few species were confined to –N squares. None of the latter group was found in abundance. The squares were divided in parcels sown with 4 species of lawn grasses. Several fungi showed preference for one or two grass species. The field consists of two parts, sown in 1977 and 1972 respectively. The immigration pattern into the new field is described.     

Neogene Fallout Tuffs from the Yellowstone Hotspot in the Columbia Plateau Region,Oregon, Washington and Idaho,USA

Sedimentary sequences in the Columbia Plateau region of the Pacific Northwest ranging in age from 16–4 Ma contain fallout tuffs whose origins lie in volcanic centers of the Yellowstone hotspot in northwestern Nevada, eastern Oregon and the Snake River Plain in Idaho. Silicic volcanism began in the region contemporaneously with early eruptions of the Columbia River Basalt Group (CRBG), and the abundance of widespread fallout tuffs provides the opportunity to establish a tephrostratigrahic framework for the region. Sedimentary basins with volcaniclastic deposits also contain diverse assemblages of fauna and flora that were preserved during the Mid-Miocene Climatic Optimum, including Sucker Creek, Mascall, Latah, Virgin Valley and Trout Creek. Correlation of ashfall units establish that the lower Bully Creek Formation in eastern Oregon is contemporaneous with the Virgin Valley Formation, the Sucker Creek Formation, Oregon and Idaho, Trout Creek Formation, Oregon, and the Latah Formation in the Clearwater Embayment in Washington and Idaho. In addition, it can be established that the Trout Creek flora are younger than the Mascall and Latah flora. A tentative correlation of a fallout tuff from the Clarkia fossil beds, Idaho, with a pumice bed in the Bully Creek Formation places the remarkably well preserved Clarkia flora assemblage between the Mascall and Trout Creek flora. Large-volume supereruptions that originated between 11.8 and 10.1 Ma from the Bruneau-Jarbidge and Twin Falls volcanic centers of the Yellowstone hotspot in the central Snake River Plain deposited voluminous fallout tuffs in the Ellensberg Formation which forms sedimentary interbeds in the CRBG. These occurrences extend the known distribution of these fallout tuffs 500 km to the northwest of their source in the Snake River Plain. Heretofore, the distal products of these large eruptions had only been recognized to the east of their sources in the High Plains of Nebraska and Kansas.     

Diversity within Serogroups of Rhizobium leguminosarum biovar viceae in the Palouse Region of Eastern Washington as Indicated by Plasmid Profiles, Intrinsic Antibiotic Resistance, and Topography

Serology, plasmid profiles, and intrinsic antibiotic resistance (IAR) were determined for 192 isolates of Rhizobium leguminosarum biovar viceae from nodules of peas (Pisum sativum L.) grown on the south slope and bottomland topographic positions in eastern Washington State. A total of 3 serogroups and 18 plasmid profile groups were identified. Nearly all isolates within each plasmid profile group were specific for one of the three serogroups. Cluster analysis of IAR data showed that individual clusters were dominated by one serogroup and by one or two plasmid profile groups. Plasmid profile analysis and IAR analysis grouped 72% of the isolates similarly. Most plasmid profile groups and several IAR clusters favored either the south slope or the bottomland topographic position. These findings show that certain intraserogroup strains possess a greater competitiveness for nodulation and/or possess a greater ability to survive in adjacent soil environments.     

Losses in the conservation and utilisation of grass and forage crops*

Losses occur during the conservation of forage crops as a result of plant respiration post-cutting and post-harvest; as a result of fermentation, surface deterioration, and (in the case of wet crops) effluent production whilst in store. Further losses occur when conserved forages are given to ruminants; the largest being that of undigested material voided in faeces. Losses during conservation and utilisation can be reduced by minimising the period of field drying and using chemical additives to improve preservation or digestibility.     

中国特有的三种榆科植物枝条内生真菌菌群多样性

为了解我国特有的3种古老的野生榆科植物内生真菌菌群多样性及探讨同一生境条件下内生真菌菌群在不同植物之间的组成特征,以安徽琅琊山国家森林公园内的野生青檀、琅琊榆和醉翁榆的当年生健康枝条为研究对象,采用组织分离法和形态分类学方法对其内生真菌进行了分离和鉴定。结果表明,从3种榆科植物的1 778个组织块中,分离内生真菌1 938株,隶属于10目16科22属,未产孢的一类暂归为无孢菌群,占10.2%。3种榆科植物均是以子囊菌类所占比例最高(80.72%–89.71%),目级水平以肉座菌目Hypocreales的相对多度最高,科级水平以间座菌科Diaporthaceae的相对多度最高,属级水平以拟茎点霉属Phomopsis的相对多度最高。琅琊榆枝条中分离的内生真菌菌群最多(14属),醉翁榆菌群最少(10属)。内生真菌菌群组成在3种榆科植物之间存在宿主特异性。Shannon指数(H′)从高到低的顺序为:青檀琅琊榆醉翁榆,Margalef指数(R)从高到低的顺序为:琅琊榆青檀醉翁榆,均匀度指数(E)从高到低的顺序为:青檀醉翁榆琅琊榆。琅琊榆和醉翁榆之间的内生真菌菌群组成相似度最高,相似性系数达0.62,青檀和琅琊榆的相似性系数最低(C_S=0.44)。费舍尔检验(Fisher’s exact test)表明,3种榆科植物在内生真菌菌群组成上无明显差异(P=0.26‐0.500.05)。     

Silicon distribution and accumulation in shoot tissue of the tropical forage grass Brachiaria brizantha

Silicon (Si) accumulation in organs and cells is one of the most prominent characteristics of plants of the family Poaceae. Many species from this family are used as forage plants for animal feeding. The present study investigates in Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu: (1) the dry matter production and Si content in shoot due to soil Si fertilizations; (2) the Si distribution among shoot parts; and (3) the silica deposition and localization in leaves. Plants of B. brizantha cv. Marandu were grown under contrasting Si supplies in soil and nutrient solution. Silica deposition and distribution in grass leaf blades were observed using light microscope and scanning electron microscope equipped with an energy dispersive X-ray spectrometer (SEM-EDXS). Silicon concentration in the B. brizantha shoot increased according to the Si supply. Silicon in grass leaves decreased following the order: mature leaf blades > recently expanded leaf blades > non-expanded leaf blades. Silicon accumulates mainly on the upper (adaxial) epidermis of the grass leaf blades and, especially, on the bulliform cells. The Si distribution on adaxial leaf blade surface is non uniform and reflects a silica deposition exclusively on the cell wall of bulliform cells.     

Physiological dormancy in seeds of two endemic species of Begonia from Yunnan Province,China: diagnosis and classification

With the purpose of assessing the status of dormancy in seeds of two Begonia species (Begonia lithophila and Begonia guishanensis), freshly matured seeds were given gibberellic acid and moist chilling and allowed to dry after ripening. The seeds were then germinated on media with or without KNO₃ at 15, 20, 25, 30 and 18/25°C. All three treatments significantly increased germination percentages. Examination by X‐ray revealed that seeds of both species have a fully developed embryo and thus have no morphological component of dormancy; seeds readily imbibed water and KNO₃ solution. Therefore, we conclude that seeds of the two Begonia species have non‐deep physiological dormancy. Although KNO₃ significantly increased germination in both species, alternating temperatures did not, suggesting that the most favorable microhabitat for germination is small‐scale disturbances under the forest canopy.     

Microscopic investigation of changes in histology and digestibility in the rumen of a forage grass and a forage legume during the first growth stage.

An Italian "Dalita" ryegrass (Lolium italicum) and a European lucerne (Medicago sativa) were harvested at 5 different growth stages to determine the anatomical factors limiting their digestibility and in particular the effects of lignification of the tissues. In vitro digestibility, cell wall contents of the whole plant and stem of lucerne and of the whole plant, stem and leaf blade of ryegrass were determined. The rate and the extent of degradation in the rumen of the different tissues were observed by scanning electron microscopy. This degradation occurred very rapidly with the lucerne stems; the xylem of lucerne was the only undegradable tissue whatever the stage. The collenchyma was degraded in the rumen although with acid phloroglucinol it stained positive for the presence of phenolic compounds. Ryegrass stems were digested more slowly than lucerne stems, and the sclerenchyma and xylem of ryegrass were indigestible whatever the stage. The parenchyma located close to the sclerenchyma became indigestible as the cell walls lignified progressively from the third stage. These results contribute to the understanding of the decrease in digestibility over the first growth stage and the variation in rate of digestion of lucerne and ryegrass in the rumen.     

Filamentous fungi from Plantago lanceolata L. leaves: Contribution to the pattern and stability of bioactive metabolites

The aim of this study was to test contribution of plant-associated microorganism (PAMs) to metabolite stability/instability in a medicinal plant matrix.Therefore, PAM strains were isolated and identified based on relevant DNA sequences from Plantago lanceolata leaves. Sterile water extracts of P. lanceolata were incubated with the isolated strains and antioxidants (ascorbic acid (AA), and EDTA) for 15 days, and changes in the concentrations of chief bioactive constituents (aucubin, catalpol, acteoside (=verbascoside)) were quantified by capillary electrophoresis. Phenolic breakdown-products were identified by GC–MS.PAMs were identified from the genera Epicoccum, Bipolaris, Cladosporium, Leptosphaerulina, Aspergillus, Eurotium and Penicillium (pathongens, endophytes, and other species). Some fungi caused significant decomposition of the chief constituents (p < 0.001). Surprisingly, some strains inhibited breakdown of acteoside (p < 0.001). Meanwhile, concentration of several phenolic acids increased in fungi-infested extracts (p < 0.001). Gentisic acid, 4-hydroxyphenyl acetic acid, 4-hydroxybenzoic acid and hydroxytyrosol were only present when the extract was infested with a PAM. The products are powerful antioxidants and chelators. Concentrations of phenolic acids influenced acteoside stability significantly (p < 0.01), as shown by basic data-mining techniques. AA and EDTA also significantly inhibited acteoside breakdown in sterile model solutions (p < 0.05).Our results suggest that the phenolic acid mixture (produced during the fungal proliferation) protected acteoside from breakdown, possibly via its antioxidant activity and metal complexing ability. It was shown that PAMs can increase or decrease the stability of chief metabolites in herbal matrices, and can significantly alter the chemical pattern of the plant matrix.     

Responses of Tribolium castaneum to olfactory cues from cotton seeds,the fungi associated with cotton seeds,and cereals

We tested, in an olfactometer, whether or not Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) responds preferentially to the volatiles that emanate from the fungi associated with cotton [Gossypium hirsutum L. (Malvaceae)] seed over those that emanate from cereals, because cereals are usually portrayed as the primary resources of these beetles. Pairwise comparisons were conducted between cotton seed, wheat (Triticum aestivum L.), and sorghum [Sorghum bicolor (L.) Moench] (both Poaceae); volatiles were tested from intact seeds and from both water and ethanol extracts. The results demonstrate that T. castaneum is attracted more strongly to cotton seeds with its lint contaminated with fungi, than to the conventional resources of this species (i.e., wheat and sorghum). Further tests prove that it is the fungus on the lint that produces the active volatiles, because the beetles did not respond to sterilized cotton lint (i.e., without the fungi typically associated with it when cotton seed is stored). Tests with five fungal cultures (each representing an unidentified species that was isolated from the field‐collected cotton lint) were variable across the cultures, with only one of them being significantly attractive to the beetles. The others were not attractive and one may even have repulsed the beetles. The results are consistent with the beetles having a strong ecological association with fungi and suggest it would be worth investigating the ecology of T. castaneum from this perspective.     

Phenotypic plasticity and population differentiation in seeds and seedlings of the grass Anthoxanthum odoratum

Summary Seeds of Anthoxanthum odoratum were transplanted reciprocally between a xeric and a mesic field population that were genetically differentiated in adult traits. In one experiment seeds were reciprocally buried in bags in the soil, in a second experiment seeds were reciprocally sown in small plots. For most traits, site effects were much larger than seed-source effects. Germination, emergence, mortality of buried seed and recruitment were significantly higher at the xeric site than at the mesic site, irrespective of population of origin. Seed dormancy, was significantly higher for seed originating from the mesic than from the xeric population. Seedling recruits originating from the xeric population tended to be larger at both sites. Fecundity of seedling recruits depended on the environment; fecundities of plants growing in the xeric site had more than double the fecundity of plants growing in the mesic site. Phenotypic plasticity rather than population differences determined variation in performance in the seed and seedling stages.     

The weedy species of Merretnia (Convolvulaceae) occurring in the Solomon Islands and a description of a new species

The genus Merremia is found in the tropical regions of both hemispheres. The climbing species with fast growth rates can become troublesome weeds of cultivation and forestry. Serveral Merremia species have become serious weeds of forestry plantations in the Solomon Islands. The important species are discussed and a new species, Merremia bracteata , found in Merremia infestations is described.     

Hot alkali-labile linkages in the walls of the forage grass Phalaris aquatica and Lolium perenne and their relation to in vitro wall digestibility

The factors affecting in vitro dry matter digestibility (IVDMD) of fully mature internodes of 150 lines of the forage grass, Phalaris aquatica, and internodes of 100 lines of perennial ryegrass (Lolium perenne), harvested just after anthesis, were investigated. The relationships between IVDMD and the contents of acetyl bromide lignin, and ester-ether linkages between lignin and wall polysaccharides, measured by hydroxycinnamic acids (HCAs) released by 4 M NaOH at 170 degrees C respectively, were determined. The regression analysis gave r(2)=0.05 and 0.03 for the relation between IVDMD and lignin content and r(2)=0.51 and 0.53 for the relation between IVDMD and the content of hot alkali-labile HCA (predominantly ferulic acid) for phalaris and ryegrass, respectively. These observations are interpreted in terms of the restricted accessibility of polysaccharide hydrolysing enzymes to their substrates in the forage cell walls by the covalent cross-linking of wall polymers through HCAs.     

A comparative study of the expression of serine proteinases in quiescent seeds and in developing Canavalia ensiformis plants

An alkaline proteinase activity is present in quiescent seeds and up to the 24th day of development of Canavalia ensiformis DC (L.) plants. By a simple protocol consisting of cation exchange chromatography, followed by an anion exchange column, a serine proteinase (Q-SP) was purified to homogeneity from quiescent seeds. Q-SP consists of a 33 kDa chain with an optimum pH between 8.0 and 9.0. Arginine residues at P1 and P2 subsites favour binding to the substrate, as shown by the KM assay with N-alpha-benzoyl-DL-arginine-4-nitroanilide-hydrochloride and N-benzoylcarboxyl-L-arginyl-L-arginine-7-amido-4-methylcoumarin. The same protocol was used for partial purification of benzamidine-sensitive enzymes from the developing plant. On the 7th day, a new benzamidine-sensitive enzyme is synthesized in the seedling, seen as the second active peak appearing in anion exchange chromatography. A benzamidine-sensitive enzyme purified from cotyledons presented a similar gel filtration profile as Q-SP, although it was eluted at different salt concentrations in the anion exchange chromatography. None of the enzymes was inhibited by PMSF, APMSF, or SBTI, but they were inactivated by benzamidine, TLCK, and leupeptin. Q-SP did not cleave in vitro C. ensiformis urease, concanavalin A, or its main storage protein, canavalin. In conclusion, a ubiquitous benzamidine-sensitive proteolytic activity was found in C. ensiformis from quiescent seeds up to 24 d of growth, which apparently is not involved in the hydrolysis of storage proteins and might participate in an as yet unidentified limited proteolysis event.     

Triterpene saponins and flavonoids in the seeds of Trifolium species

Seeds of 57 species of the genus Trifolium have been studied for the occurrence and concentration of soyasapogenol B glycosides and flavonoids. It was shown that all tested species contained soyasaponin I and in some species astragaloside VIII and/or 22-O-glucoside and 22-O-diglucoside of soyasaponin I were also present. Total concentration of saponins ranged from trace amounts up to 10 mg/g(DM). It was suggested that soyasapogenol B glycosides could be recognized as chemotaxonomic character of Fabaceae family. All but three tested species contained flavonoids. The majority of species contained quercetin as a sole flavonoid or in the mixture with a number of unidentified flavonoid components. Concentration of quercetine in some species was at the level of about 3 mg/g(DM). This high quercetin concentration and soyasaponin occurrence makes the seeds of some Trifolium species a potential source of health beneficial phytochemicals, to be used in human nutrition.     

Dichotomy in the NRT gene families of dicots and grass species

A large proportion of the nitrate (NO(3)(-)) acquired by plants from soil is actively transported via members of the NRT families of NO(3)(-) transporters. In Arabidopsis, the NRT1 family has eight functionally characterised members and predominantly comprises low-affinity transporters; the NRT2 family contains seven members which appear to be high-affinity transporters; and there are two NRT3 (NAR2) family members which are known to participate in high-affinity transport. A modified reciprocal best hit (RBH) approach was used to identify putative orthologues of the Arabidopsis NRT genes in the four fully sequenced grass genomes (maize, rice, sorghum, Brachypodium). We also included the poplar genome in our analysis to establish whether differences between Arabidopsis and the grasses may be generally applicable to monocots and dicots. Our analysis reveals fundamental differences between Arabidopsis and the grass species in the gene number and family structure of all three families of NRT transporters. All grass species possessed additional NRT1.1 orthologues and appear to lack NRT1.6/NRT1.7 orthologues. There is significant separation in the NRT2 phylogenetic tree between NRT2 genes from dicots and grass species. This indicates that determination of function of NRT2 genes in grass species will not be possible in cereals based simply on sequence homology to functionally characterised Arabidopsis NRT2 genes and that proper functional analysis will be required. Arabidopsis has a unique NRT3.2 gene which may be a fusion of the NRT3.1 and NRT3.2 genes present in all other species examined here. This work provides a framework for future analysis of NO(3)(-) transporters and NO(3)(-) transport in grass crop species.