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.     

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.     

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.     

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.     

Materials for Chinese Ainsliaea (Compositae)

The genus, Ainsliaea DC. from China is revised in this paper. Three species, A. nana Y. C. Tseng, A. pingbianensis Y. G. Tseng and A. trinervis Y. C. Tseng, are newly described; two species, A. chapaensis Merr. and A. angustifolia Hook. f. et Thoms. ex C. B. Clarke are new records for China and two new combinations, A. apteroides (Chang) Y. C. Tseng and A. macrocephala (Mattf.) Y. C. Tseng, are made. In addition, one species, A. hypoleuca Diels ex Limpr. and four varieties, A. bonatii Beauverd var. arachnoidea Beauverd, A. pteropoda DC. var. leiophylla Franch., A. elegans Hemsl. var. tomentosa Mattf. and A. glabra Hemsl. var. tenuiculis (Mattf.)Chang, are reduced to synonyms.     

Complete chloroplast genome sequences of <Emphasis Type="Italic">Hordeum vulgare</Emphasis>, <Emphasis Type="Italic">Sorghum bicolor</Emphasis> and <Emphasis Type="Italic">Agrostis stolonifera</Emphasis>, and comparative analyses with other grass genomes

Comparisons of complete chloroplast genome sequences of Hordeum vulgare, Sorghum bicolor and Agrostis stolonifera to six published grass chloroplast genomes reveal that gene content and order are similar but two microstructural changes have occurred. First, the expansion of the IR at the SSC/IRa boundary that duplicates a portion of the 5' end of ndhH is restricted to the three genera of the subfamily Pooideae (Agrostis, Hordeum and Triticum). Second, a 6 bp deletion in ndhK is shared by Agrostis, Hordeum, Oryza and Triticum, and this event supports the sister relationship between the subfamilies Erhartoideae and Pooideae. Repeat analysis identified 19-37 direct and inverted repeats 30 bp or longer with a sequence identity of at least 90%. Seventeen of the 26 shared repeats are found in all the grass chloroplast genomes examined and are located in the same genes or intergenic spacer (IGS) regions. Examination of simple sequence repeats (SSRs) identified 16-21 potential polymorphic SSRs. Five IGS regions have 100% sequence identity among Zea mays, Saccharum officinarum and Sorghum bicolor, whereas no spacer regions were identical among Oryza sativa, Triticum aestivum, H. vulgare and A. stolonifera despite their close phylogenetic relationship. Alignment of EST sequences and DNA coding sequences identified six C-U conversions in both Sorghum bicolor and H. vulgare but only one in A. stolonifera. Phylogenetic trees based on DNA sequences of 61 protein-coding genes of 38 taxa using both maximum parsimony and likelihood methods provide moderate support for a sister relationship between the subfamilies Erhartoideae and Pooideae.     

New Taxa of Chinese Aristolochia L.

Four new species of the genus Aristolochia (Aristolochiaceae) are described as new from China. They are Aristolochia austrochinensis C. Y. Cheng & J. S. Ma, A. caulialata C. Y. Wu, A. salweenensis C. Y. Cheng & J. S. Ma, and A. kunmingensis C. Y. Cheng &J. S. Ma. A naturalized species, A. ringens Vahl is also reported.     

A new species of Agrostis (Gramineae) in the A. alpina complex

A new species of Agrostis L. (A. barceloi ) is described from the northern mountains of Mallorca (Balearic Islands). The new taxon belongs to sect. Agtush and is mainly related to A. alpina Scop. and A. schleicheri Jord. & Verl. on morphological grounds. However, A. barceloi differs from A. alpina by its narrowly-lanceolate inflorescence, with panicle branches erect during and after anthesis, non-scabrid leaves, and by smaller lemmas and others. The new species is distinguished from A. schleicheri by the smaller spikelets, lemma, palea, and anthers. In addition, A. barceloi is tetraploid (2n = 28), and differs cytologically from the diploid A. alpina (2n= 14) and the hexaploid A. schleicheri (2n = 56).     

ENDOPHYTE-HOST ASSOCIATIONS IN GRASSES. XVI. PATTERNS OF ENDOPHYTE DISTRIBUTION IN SPECIES OF THE TRIBE AGROSTIDEAE

Distribution of Acremonium endophytes in several species of Agrostideae is determined through surveys conducted in the field and in grass herbaria. Widespread geographic distribution of Acremonium in a particular grass species may indicate early colonization of the grass as a host, while a narrow pattern of geographic distribution suggests more recent colonization of the grass. Two grasses that appear to show a narrow endophyte distribution include Agrostis alba and Ammophila breviligulata. Cultural features of endophytes from several grasses are compared. A new variety of Acremonium typhinum is proposed to accommodate the endophyte from A. breviligulata. An endophyte in Agrostis alba is identified as Acremonium starrii. It is also suggested that Acremonium endophytes are spreading in grasses and may be progressively colonizing new hosts.     

Cytochrome and alternative pathway activity in roots of thermal and non-thermal Agrostis species in response to high soil temperature

Partitioning of respiration between the cytochrome pathway (CP) and the alternative pathway (AP) may play an important role in plant adaptation to extreme environments. We examined changes in partitioning between CP and AP, and viability of roots associated with plant exposure to high soil temperature for two Agrostis species: Agrostis scabra Willd., a species adapted to high-temperature soils in geothermal areas in Yellowstone National Park, and Agrostis stolonifera L. (cv. Penncross) a heat-sensitive grass widely used in cool-climate regions. Roots of A. scabra and A. stolonifera were exposed to soil temperature of 37 or 20°C, while shoots were exposed to 20°C for 28 days. Root viability decreased, and total root respiration increased for both species at 37°C. The decline in root viability and the increase in respiration rates were less pronounced for A. scabra than for A. stolonifera . A larger proportion of total root respiration was attributed to the AP in A. scabra compared with that in A. stolonifera when both species were exposed to 37°C. At 7 and 14 days at 37°C, the relative proportion of respiration passing through AP increased by 12 and 10%, respectively, in A. scabra , whereas in A. stolonifera , AP increased by 4 and 1%, respectively. Our results suggest that maintaining a higher proportion of AP at a high soil temperature may contribute to root thermo-tolerance in A. scabra in comparison with A. stolonifera , and alternative respiration may play an important role in plant adaptation to high soil temperature.     

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.     

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.     

中国顶丝藻科（Acrochaetiaceae）新记录I

中国顶丝藻科新记录６种。密集旋体藻Ａｕｄｏｕｉｎｅｌｌｅｄｅｎｓａ,亮管旋体藻Ａ．ｈｙａｌｏｓｉｐｈｏｎｉａｅ,小旋体藻Ａ．ｐａｒｖｕｌａ,羽状旋体藻Ａ．ｐｌｕｍｏｓａ,顶生旋体藻Ａ．ｔｅｒｍｉｎａｌｉｓ,图氏旋体藻Ａ．ｔｈｕｒｅｔｉｉ。     

Karyotype Analysis of 5 Species of Genus Astragalus

The karyotypes of five species in Astragalus (A. dahuricus DC., A. mongolicus Bunge., A. adsurgens Pall., A. melilotoides Pell., A. huangheensis H. C. Fu., Y. H. Liu) were studied. Among them, the karyotypes of A. dahuricus and A. melilotoides are reported for the first time. While A. melilotoides is tetraploid (2n=4X=32), all the others are found to be diploid (2n= 2X = 16). Based on the comparison of karyotypes, the evolu-tionary order of these 5 species is discussed.     

New Agrostis from the California coast

Agrostis clivicola, A. clivicola var.punta-reyesensis andA. blasdalei var.marinensis are described from the California coast. A key distinguishes these from other species of similar habit and habitat.     

Rhizomatous grass weeds and Ophiobolus graminis Sacc

An account is given of the infection of grass weeds by Ophiobolus granwm in a wheat crop affected by the disease. It was shown that the fungus was carried by the rhizomatous grasses, Agropyron repens and Agrostis spp. and also by Holcus lanatus. Examination of these showed the importance of Agrostis spp. in carrying over the mycelium under field conditions.     

黄曲霉群菌种产生黄曲霉毒素B_1的调查研究

本文对来自我国20个省、市、自治区的不同基物上分离的和中国科学院微生物研究所菌种保藏室以及其他单位提供的黄曲霉群菌种,经随机选取82株进行了黄曲霉毒素B_1的测定,证明在测试的9个已知分类群中产生黄曲霉毒素B_1的菌种只限于寄生曲霉和黄曲霉,另外4株种名未定者也能产生此种毒素。在黄曲霉中产毒菌株约占30％(28.3％),其在GAN(葡萄糖硝酸铵)和大米培养基中的黄曲霉毒素B_1的最高产量分别为133,333.3和160,000.0ppb。总的来说,大体上可以反映在我国一般基物上黄曲霉产毒菌株存在的现状。在实验过程中,还对黄曲霉群菌种在GAN和大米培养基中黄曲霉毒素B_1的产量和产毒菌株数作了比较。发现在大米培养基中黄曲霉毒素B_1的产量高于GAN,而且测试的黄曲霉产毒菌株在这两种培养基中均各有不能产毒的菌株,因此,在测定产毒菌株时,若仅采用其中一种产毒培养基,往往会有漏掉产毒菌株的可能性。     

Root respiratory characteristics associated with plant adaptation to high soil temperature for geothermal and turf-type Agrostis species

Respiration is a major avenue of carbohydrates loss. The objective of the present study was to examine root respiratory characteristics associated with root tolerance to high soil temperature for two Agrostis species: thermal Agrostis scabra, a species adapted to high-temperature soils in geothermal areas in Yellowstone National Park, and two cultivars ('L-93' and 'Penncross') of a cool-season turfgrass species, A. stolonifera (creeping bentgrass), that differ in their heat sensitivity. Roots of thermal A. scabra and both creeping bentgrass cultivars were exposed to high (37 degrees C) or low soil temperature (20 degrees C). Total root respiration rate and specific respiratory costs for maintenance and ion uptake increased with increasing soil temperatures in both species. The increases in root respiratory rate and costs for maintenance and ion uptake were less pronounced for A. scabra than for both creeping bentgrass cultivars (e.g. respiration rate increased by 50% for A. scabra upon exposure to high temperature for 28 d, as compared with 99% and 107% in 'L-93' and 'Penncross', respectively). Roots of A. scabra exhibited higher tolerance to high soil temperature than creeping bentgrass, as manifested by smaller decreases in relative growth rate, cell membrane stability, maximum root length, and nitrate uptake under high soil temperature. The results suggest that acclimation of respiratory carbon metabolism plays an important role in root survival of Agrostis species under high soil temperatures, particularly for the thermal grass adaptation to chronically high soil temperatures. The ability of roots to tolerate high soil temperatures could be related to the capacity to control respiratory rates and increase respiratory efficiency by lowering maintenance and ion uptake costs.     

中国蘑菇属新种和新记录种

本文报道我国蘑菇属(Agaricus)43种、2变种。其中新种3个:翘鳞蘑菇Agaricus squ arrosus Li sp. nov.,异鳞蘑菇A. dimorphosquamatus Li sp. nov.,假环柄蘑菇A. lepioti formis Li sp. nov.。本文所研究的全部标本保藏于中国科学院微生物研究所真菌标本名(HMAS)。