Ovipositional preferences and larval survival of annual bluegrass weevil,Listronotus maculicollis,on Poa annua and selected bentgrasses (Agrostis spp.)

The annual bluegrass weevil (ABW), Listronotus maculicollis Kirby (Coleoptera: Curculionidae), is a serious and expanding pest of short‐cut turfgrass on golf courses in eastern North America. Increasing problems with the development of insecticide resistance in this pest highlights the need for more sustainable management approaches. Plant resistance is one of the most promising alternative strategies. Bentgrasses are the dominant grass species on golf course fairways, tees, and putting greens in the areas affected by ABW. But Poa annua L. (Poaceae), a highly invasive weed, often constitutes a large percentage of turf stands in short‐mown golf courses and is thought to be particularly susceptible to ABW. We studied resistance to ABW in four cultivars of creeping bentgrass, Agrostis stolonifera L., and two cultivars each of colonial bentgrass, Agrostis capillaris L., and velvet bentgrass, Agrostis canina L. (Poaceae), in comparison with P. annua by addressing the three major components of resistance: antixenosis (adult ovipositional and feeding preferences), antibiosis (larval survival and growth), and grass tolerance (grass damage). Our findings suggest that antixenosis/non‐preference is at least partially involved in bentgrass resistance to ABW. Even though oviposition was observed in all tested grasses, females laid significantly fewer eggs in Agrostis spp. than in P. annua. Compared to P. annua, Agrostis spp. were also less suitable for larval development with lower numbers of ABW immatures recovered and larvae weighing less and being less advanced in development. Resistance levels to ABW larvae varied significantly among Agrostis spp. and cultivars. Agrostis canina was least preferred by females for oviposition and A. stolonifera was the least suitable for larval survival and development. Agrostis spp., especially A. stolonifera, were more tolerant to ABW feeding than P. annua. Our findings suggest that reduction in P. annua and replacement with Agrostis spp., especially A. stolonifera, wherever feasible should be integral to more sustainable approaches to ABW management.     

Genetic diversity in colonial bentgrass (Agrostis capillaris L.) revealed by EcoRI-MseI and PstI-MseI AFLP markers.

Colonial bentgrass (Agrostis capillaris L.) is a potential source for genetic improvement of resistance to environmental stress and disease for other bentgrass species (Agrostis spp.). To conserve and study the existing genetic resources of colonial bentgrass for use in breeding, genetic diversity was investigated using amplified fragment length polymorphism (AFLP) markers. Included in this study were 22 accessions from US Department of Agriculture germplasm collected from 11 countries, in conjunction with 14 accessions from northern Spain and 3 commercial cultivars. Ten EcoRI-MseI and 6 PstI-MseI AFLP primer combinations produced 181 and 128 informative polymorphic bands, respectively. Cluster analysis of genetic similarity estimates revealed a high level of diversity in colonial bentgrass species with averages of 0.51 (EcoRI-MseI) and 0.63 (PstI-MseI). Greater genetic diversity was detected by the EcoRI-MseI AFLP primer combinations. A low but significant positive correlation (r = 0.44, p = 0.0099) between the 2 Jaccard similarity matrices was obtained by the Mantel test. Commercial cultivars of bentgrass showed a narrow genetic background. The assessment of genetic diversity among colonial bentgrass accessions suggested the potential value of the colonial bentgrass germplasm in turfgrass cultivar improvement.     

Colonization by alpine native plants of a stabilized road verge on the Bogong High Plains, Victoria

Summary Although many native species are now used in the revegetation of soil disturbances in Australian alpine areas, exotic species were, until recently, the only components of seed mixes. The use of exotic species and fertilizer was justified by their availability and low cost, and the prediction that native species would replace the exotic sward, presumably once soil nutrient levels dropped to those found in native vegetation. There was no apparent regard for the invasive capacities of the exotic species used. An investigation of a road verge on the Bogong High Plains, revegetated with a mixture of exotic species in the late 1950s, has shown that colonization by native plants can be very slow. Although many native species had colonized by 1993, exotic species still provided 50% of the cover. Agrostis capillaris accounted for most of this. The major native colonizers were Carex spp., Colobanthus affinis , Euchiton spp., Leptinella filicula , Poa hiemata , Ranunculus victoriensis and Scleranthus biflorus . Poa hiemata provided by far the most cover of the native colonizers. There have been considerable increases in the cover and number of native species on the verge since 1989. Cattle grazing and trampling are likely to have limited colonization of native plants prior to the removal of livestock in 1991. Recommendations are made on approaches to future revegetation in the alpine area.     

Early changes in species composition of upland sown grassland under extensive grazing management

Abstract. Due to economic pressures and policy changes Lolium perenne‐Trifolium repens sown swards in upland UK sheep systems are likely to become less intensively managed. We present results from the first 5 yr of a long‐term experiment studying vegetation change under more extensive grazing management at three sites. One treatment was representative of current, intensive management and 5 were unfertilized with different intensities of seasonal grazing. The species composition of unfertilized, ungrazed swards changed dramatically within 2 yr and the sown species had virtually disappeared by year 5. Ranunculus repens, Poa trivialis, Agrostis gigantea, Juncus spp. and Carex spp. became dominant at the wettest site. Grasses were dominant at the other sites. In contrast, the sown species were retained in the unfertilized, grazed treatments; there were small shifts in abundance of the species present initially and few additions or losses of species. Some colonizing species were present in the seed bank whereas others with a transient seed bank appeared to have invaded from neighbouring vegetation. Implications of these results for compensation schemes to reduce animal output and increase biodiversity are discussed.     

The competition between barley and certain weeds under controlled conditions; competition with Agrostis gigantea

The twitch grass Agrostis gigantea var. dispar occurs commonly as a serious weed on the light semi-acid soils found on the lower greensand near Woburn, Beds. It spreads rapidly by means of rhizomes, rarely forming stolons. All the rhizome growth takes place within 6 in. of the surface: I g. dry weight of roots and rhizomes may occupy up to 260 C.C. of soil. A. gigantea is slightly more easily eradicated than Holcus mollis.
When barley and this Agrostis are planted together, with abundance of water and nutrients for both, it is found that increasing the density of planting of the barley reduces the crop loss due to Agrostis competition, but the weed can, nevertheless, diminish the yield of close-planted barley by about a quarter. In a sparse crop of barley, any increase in Agrostis growth is reflected in an almost equal reduction in yield of barley. In proportion to its relative density the barley secures a larger share of the soil nitrogen than does the Agrostis.
Evidence is given suggesting that there is a marked effect of the one grass on the other even when there is no competition for root space and an ample supply of water and nutrients.     

Revealing constitutively expressed resistance genes in Agrostis species using PCR-based motif-directed RNA fingerprinting

Agrostis species are mainly used in athletic fields and golf courses. Their integrity is maintained by fungicides, which makes the development of disease-resistance varieties a high priority. However, there is a lack of knowledge about resistance (R) genes and their use for genetic improvement in Agrostis species. The objective of this study was to identify and clone constitutively expressed cDNAs encoding R gene-like (RGL) sequences from three Agrostis species (colonial bentgrass (A. capillaris L.), creeping bentgrass (A. stolonifera L.) and velvet bentgrass (A. canina L.)) by PCR-based motif-directed RNA fingerprinting towards relatively conserved nucleotide binding site (NBS) domains. Sixty-one constitutively expressed cDNA sequences were identified and characterized. Sequence analysis of ESTs and probable translation products revealed that RGLs are highly conserved among these three Agrostis species. Fifteen of them were shown to share conserved motifs found in other plant disease resistance genes such as MLA13, Xa1, YR6, YR23 and RPP5. The molecular evolutionary forces, analysed using the Ka/Ks ratio, reflected purifying selection both on NBS and leucine-rich repeat (LRR) intervening regions of discovered RGL sequences in these species. This study presents, for the first time, isolation and characterization of constitutively expressed RGL sequences from Agrostis species revealing the presence of TNL (TIR-NBS-LRR) type R genes in monocot plants. The characterized RGLs will further enhance knowledge on the molecular evolution of the R gene family in grasses.     

Lifetime reproductive success and density-dependent, multi-variable resource selection

Individuals are predicted to maximize lifetime reproductive success (LRS) through selective use of resources; however, a wide range of ecological and social processes may prevent individuals from always using the highest-quality resources available. Resource selection functions (RSFs) estimate the relative amount of time an individual spends using a resource as a function of the proportional availability of that resource. We quantified the association between LRS and coefficients of individual-based RSFs describing lifetime resource selection for 267 female red deer (Cervus elaphus) of the Isle of Rum, Scotland, from 1970 to 2001. LRS was significantly related to first- and second-order effects of selection for Agrostis/Festuca grassland and proximity to the sea coast (quality of forage within Agrostis/Festuca grassland was highest nearest the coast (ratio of short:long grassland)). The benefits of selecting for quality in Agrostis/Festuca grassland, however, traded-off with increases in LRS gained by avoiding conspecific density. LRS was inversely associated with local density, which was highest along the coast, and reproductive benefits of selecting Agrostis/Festuca grassland diminished with increasing density. We discuss the relevance of these results to our understanding of the spatial distribution of red deer abundance, and potential applications of our approach to evolutionary and applied ecology.     

The vegetation of ultrabasic soils on the Isle of Rhum II. The causes of the debris

Summary

The relationship between the Rhum ultrabasic skeletal soils and their debris vegetation was investigated by plant analyses and field and laboratory experiments. Samples of Agrostis vinealis, Arenaria norvegica ssp norvegica, Calluna vulgaris, Festuca vivipara, Plantago maritima and Racomitrium lanuginosum from these soils usually had low concentrations of potassium and calcium, and high concentrations of sodium, magnesium (and high Mg/Ca quotients), iron and nickel. There were instances of very high iron concentrations (up to 22.4mg g^?1 in Plantago maritima), very high Mg/Ca quotients (up to 27.8 in Arenaria novegica spp. norvegica) and high nickel concentrations (up to 0.48mg g^?1 in Plantago maritima). A nutrient addition experiment which was set up in 1965 on an exposed barren area had in 1982 over twice as many species as originally recorded and a nearly complete plant cover. Shorter-term work has confirmed that nutrient availability limits the ultrabasic vegetation. An experiment on Agrostis vinealis in simulated soil solutions showed that a gabbro (non-ultrabasic) clone had a higher R.G.R. (relative growth rate), even at the higher of two experimental Mg/Ca quotients, than two peridotite (ultrabasic) clones and was moreover not significantly affected by the higher nickel concentration used. It is concluded that the low vegetation cover on the skeletal soils is maintained by low soil nutrients which might interact with the coarsely sandy texture in exacerbating the effects of periodic drought and frost heaving. There is no unequivocal evidence for plant toxicities associated with high magnesium or nickel in the Rhum soils.     

Seasonal changes in circadian grazing patterns of Kerry cows (Bos Taurus) in semi-feral conditions in Killarney National Park, Co. Kerry, Ireland

Domestic cattle generally graze during the day although some night-time grazing also occurs. However, questions remain as to the effect of management on circadian grazing patterns. This study provides for the first time a quantification of seasonal, circadian and animal variation in grazing behaviour and grazing time in cattle in semi-wild conditions.The objectives of the study were to examine how daily grazing times and the temporal distribution of grazing activity changed with season and to examine the extent to which grazing patterns were influenced by day-length. A group of 12 heifers of the Kerry breed continuously grazed a lowland field of 4.7ha. The old permanent pasture sward was dominated by Holcus spp. and Agrostis spp. Feed availability was never limiting. Length and periodicity of grazing were recorded using vibracorders attached to the necks of seven animals.Results showed that daily grazing times remained constant over most of the grazing season (circa 10-11h per day), however, some variation occurred late in the season. The temporal distribution of grazing activity changed as the season advanced so that by October grazing patterns became significantly different to those of July. The time interval between grazing bouts at dawn and dusk decreased with decreasing day-length. An increased percentage of night-time grazing occurred at shorter day-lengths.It is concluded that there is a significant seasonal effect of day-length on temporal distribution of grazing activity with night-time grazing featuring more as day-length decreases. The maintenance of similar total daily grazing times in the face of changing day-length (with the exception of late in the season) suggests that daily grazing times are a function of the attainment of a relatively constant nutritional requirement by the animal.     

Development of novel chloroplast microsatellite markers to identify species in the Agrostis complex (Poaceae) and related genera

We needed a reliable way to identify species and confirm potential interspecific and intergeneric hybrids in a landscape level study of gene flow from transgenic glyphosate-resistant Agrostis stolonifera (Poaceae) to compatible relatives. We developed 12 new polymorphic chloroplast microsatellite markers to aid in identifying species recipient of transgenic pollen both within the Agrostis complex and the related genera Polypogon.     

New Taxa of the Genus Agrostis from Yunnan

In the paper two species and one variety of the genus Agrostis L. are described as new from Yunnan Province, China. They are Agrostis lushuiensis,A. kunmingensis and A. myriantha Hook. f. var. yangbiensis.     

Agrostis mertensii (Poaceae) in hokkaido

Populations of theAgrostis flaccida-mertensii complex in Hokkaido were examined as part of the taxonomic study of this complex, which has a wide range and comprises a polyploid series of 2x–8x (x=7). The principal aim was to clarify the taxonomic status of hexaploids growing in Hokkaido. Field explorations were made in the mountains and on the coasts in Hokkaido, and the materials were gathered from 19 localities. The occurrence of four cytotypes (2x, 4x, 6x, 8x), as well as some triploids and septaploids, of this complex in Hokkaido was confirmed, and the ranges of respective cytotypes were delineated. Morphological examinations showed that diploids, triploids and tetraploids are referable toAgrostis flaccida and octoploids toA. mertensii. The hexaploids of Hokkaido were morphologically different fromA. flaccida and also from the related hexaploid species,A. tateyamensis, distributed in Honshu. The hexaploids were quite similar to octoploidA. mertensii in all the morphological features examined and also in habitat preference. Septaploids were sterile hybrids between hexaploids and octoploids. A conclusion was drawn that the hexaploid plant of Hokkaido should be grouped with the octoploid in one and the same species,Agrostis mertensii Trin.Agrostis mertensii in this amended sense is discussed from a cytogeographical viewpoint.     

高温干旱下两种冷季型草坪草叶片细胞超微结构的变化

多年生黑麦草和葡匐股颖在36℃下,控水处理6d,叶片细胞的超微结构与对照相比发生明显变化,叶绿体肿胀,被膜和片层破损,部分叶绿体变圆并向细胞中央移位,这可能有利于减少对阳光的吸收;线粒体和脂质球体数量增加;葡匐翦股颖的线粒体脊解体,但黑麦草的线粒体只受轻微影响。结果说明,两种草坪草的耐热性都较弱,但多年生黑麦草的耐热性稍强于匐匐剪胶颖。     

Genetic and historical relationships among geothermally adapted Agrostis (bentgrass) of North America and Kamchatka: evidence for a previously unrecognized, thermally adapted taxon

Agrostis species have been known to evolve ecotypes rapidly in response to unusual edaphic conditions. The geographic distribution of Agrostis taxa in Lassen Volcanic National Park (California) and Yellowstone National Park (Wyoming) in the United States and the Valley of the Geysers (Kamchatka Peninsula) in Russia suggests that Agrostis scabra might have independently evolved morphologically similar ecotypes several times. We used RAPDs to show that, contrary to expectation, the thermal populations are not independently evolved, but instead constitute a single taxon that currently has four names. A UPGMA including the four thermal and nine nonthermal Agrostis taxa showed that the thermal cluster divides into geographically distinct subclusters, but that two morphologically distinct thermal taxa do not cluster independently. Even though currently confused with the thermal populations, nonthermal A. scabra is not closely related. An analysis of molecular variance (AMOVA) showed significant differentiation between the thermal populations and the nonthermal species sampled in this study. Splitting a hypothesized thermal operational taxonomic unit (OTU) into its components (geographically separated populations) does not greatly affect the partitioning of variation among OTUs. All thermal populations therefore should be assigned to the same taxon, but its taxonomic rank cannot be determined at this time.     

Assimilation and allocation of carbon and nitrogen of thermal and nonthermal Agrostis species in response to high soil temperature

We studied whether changes in the assimilation and allocation of carbon and nitrogen are associated with plant tolerance to high soil temperatures. Two Agrostis species, thermal Agrostis scabra, a species adapted to high-temperature soils in geothermal areas in Yellowstone National Park (USA), and two cultivars of a cool-season species, Agrostis stolonifera, L-93 and Penncross, were exposed to soil temperatures of 37 or 20 degrees C, while shoots were exposed to 20 degrees C. Net photosynthesis rate, photochemical efficiency, NO(3) (-)-assimilation rate and root viability decreased with increasing soil temperatures in both species. However, the decreases were less pronounced for A. scabra than for both A. stolonifera cultivars. Carbon investment in growth of plants exposed to 37 degrees C decreased more dramatically in both A. stolonifera cultivars than in A. scabra. Nitrogen allocation to shoots was greater in A. scabra than in both creeping bentgrass cultivars at 37 degrees C soil temperature. Our results demonstrate that plant tolerance to high soil temperature is related to efficient expenditure and adjustment of C- and N-allocation patterns between growth and respiration.     

Reverse-phase high-performance liquid chromatography of Cd-binding proteins from the grass Agrostis gigantea

The Cd-binding protein fraction from roots of the grass Agrostis gigantea Roth was resolved by reverse-phase high-performance liquid chromatography. Two Cd-binding proteins containing exclusively cysteine, glutamate/glutamine (Glx), serine and glycine in different ratios were isolated. Glx was at the N-terminus of each protein.     

The first linkage map of the plant-pathogenic basidiomycete Typhula ishikariensis.

Speckled snow mold, caused by the basidiomycete Typhula ishikariensis Imai, is one of the most prominent winter diseases on perennial grasses and cereal crops in the northern hemisphere. The first linkage map of T. ishikariensis was constructed using a population of 93 sibling monokaryons derived from a single dikaryotic hybrid isolate that was created by a hyphal fusion of two monokaryotic parental isolates. The parental isolates were produced from a pathogenic dikaryotic isolate collected from a golf course in Wisconsin. The two parents exhibit significant differences in the production of aerial mycelium and sclerotia, and in their aggressiveness on creeping bentgrass (Agrostis stolonifera L.). A total of 251 loci were mapped, comprising 89 inter-simple sequence repeat (ISSR) and 160 random amplified polymorphic DNA (RAPD) markers along with 2 phenotype-based mating-type (MAT) loci. The MAT loci were mapped on linkage groups (LGs) 1 and 7. The markers were evenly distributed over 7 LGs, covering 436 cM with an average marker interval of 2.2 cM. Seven chromosomes were cytologically observed using germ tube bursting methods with acetocarmine staining. This reference linkage map of T. ishikariensis should provide a framework for the mapping of quantitatively controlled traits such as fungal growth, survival, and virulence/avirulence under low temperatures. The map should also be utilized for studying the genome organization of the cold-loving plant-pathogenic Typhula spp. and for comparative genome analysis among fungal taxa.     

Role of Copper Binding, Absorption, and Translocation in Copper Tolerance of Agrostis gigantea Roth

The capacity of roots to accumulate and retain copper was examinedin two clones of Agrostis gigantea which differ in their toleranceto excess copper. Root elongation growth in the non-tolerantclone was completely inhibited by 16 mmol m^–3 Cu whereas40 mmol m^–3 was required for inhibition in the tolerantclone. The amount of readily exchangeable copper was greaterin roots of the tolerant clone than in the non-tolerant clone.The higher capacity for binding copper did not prevent the entryof copper into the cells of intact or excised roots of the tolerantclone. Roots of both clones contained similar amounts of copperafter removal of the readily exchangeable fraction. More copperwas translocated to the shoots of the tolerant than the non-tolerantclone. The explanation of copper tolerance in Agrostis giganteamust be sought in areas other than those of differences in grosscopper absorption and retention by roots.     

The Effect of Long-Term Cd and Ni Exposure on Seed Endophytes of Agrostis capillaris and Their Potential Application in Phytoremediation of Metal-Contaminated Soils

We examined whether long-term Cd exposure leads to beneficial changes in the cultivable endophytic bacteria present in the seeds of Agrostis capillaris. Therefore the cultivable seed endophytes of Agrostis capillaris growing on a long-term Cd/Ni-contaminated plot (Cd/Ni seeds) were compared with those originating from a non-contaminated plot (control seeds). We observed plant- and contaminant-dependent effects on the population composition between control and Cd/Ni seeds. Also differences in phenotypic characteristics were found: endophytes from Cd/Ni seeds exhibited more ACC deaminase activity and production of siderophores and IAA, while endophytes from control seeds, very surprisingly, showed more metal tolerance.

Finally, the 3 most promising seed endophytes were selected based on their metal tolerance and plant growth promoting potential, and inoculated in Agrostis capillaris seedlings. In case of non-exposed plants, inoculation resulted in a significantly improved plant growth; after inoculation of Cd-exposed plants an increased Cd uptake was achieved without affecting plant growth. This indicates that inoculation of Agrostis with its seed endophytes might be beneficial for its establishment during phytoextraction and phytostabilisation of Cd-contaminated soils.