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1.
Three grass host species--tall fescue, Festuca arundinacea Schreber; meadow fescue, Festuca pratensis Hudson; and perennial ryegrass, Lolium perenne L.--each infected with a number of different Neotyphodium endophyte isolates, were investigated for their effects on fall armyworm, Spodoptera frugiperda (J.E. Smith). Alkaloid profiles varied among associations. Choice and no-choice tests comparing feeding and early development of S. frugiperda larvae on endophyte-infected and endophyte-free leaf blade material were performed. Endophyte-mediated resistance to S. frugiperda was greatest in meadow fescue and weakest in tall fescue. Some endophyte isolates, particularly in perennial ryegrass and meadow fescue, had a major effect on feeding and development of S. frugiperda, whereas others had no effect or were only weakly efficacious. In tall fescue, some associations deterred S. frugiperda from feeding in choice tests but had no effect on development, whereas larvae reared on other associations weighed significantly more than control larvae fed endophyte-free grass. It was concluded that the deleterious consequences of endophyte infection were easily masked by other factors in tall fescue. Relative leaf age had no effect on feeding preferences in the three host species. Chemical analysis of herbage from the plants used, and results from a no-choice study using spiked artificial diets, failed to individually implicate any of the major known alkaloids (peramine, lolitrem B, ergovaline, and lolines) in the observed effects on S. frugiperda. Hypotheses explaining these observations, and their impact on creating desirable grass-endophyte associations for use in pastures, are discussed.  相似文献   

2.
Leaf and tiller development in vegetative plants of S.37 cocksfoot (Dactylis glomerata L.), S.215 meadow fescue (Festuca pratensis Huds.) and S.24 perennial rye-grass (Lolium perenne L.) were measured in photoperiods varied by extending a basic period of natural light with low-intensity artificial illumination so that all plants received approximately the same amount of light each day. Increasing the photoperiod usually increased leaf length and sometimes leaf width, but decreased rate of production of leaves. However, the rate of production of new leaf surface increased with photoperiod. Increasing the photoperiod generally decreased the rate of tillering; thus, plants grown in long days had few tillers with large leaves and sheaths, in short days, plants developed more but smaller tillers.  相似文献   

3.
Summary Tall fescue (Festuca arundinacea Schreb.) protoplasts, inactivated by iodoacetamide, and non-morphogenic Italian ryegrass (Lolium multiflorum Lam.) protoplasts, both derived from suspension cultures, were electrofused and putative somatic hybrid plants were recovered. Two different genotypic fusion combinations were carried out and several green plants were regenerated in one of them. With respect to plant habitus, leaf and inflorescence morphology, the regenerants had phenotypes intermediate between those of the parents. Southern hybridization analysis using a rice ribosomal DNA probe revealed that the regenerants contained both tall fescue- and Italian ryegrass-specific-DNA fragments. A cloned Italian ryegrass-specific interspersed DNA probe hybridized to total genomic DNA from Italian ryegrass and from the green regenerated somatic hybrid plants but not to tall fescue. Chromosome counts and zymograms of leaf esterases suggested nuclear genome instability of the somatic hybrid plants analyzed. Four mitochondrial probes and one chloroplast DNA probe were used in Southern hybridization experiments to analyze the organellar composition of the somatic hybrids obtained. The somatic hybrid plants analyzed showed tall fescue, additive or novel mtDNA patterns when hybridized with different mitochondrial gene-specific probes, while corresponding analysis using a chloroplast gene-specific probe revealed in all cases the tall fescue hybridization profile. Independently regenerated F. arundinacea (+) L. multiflorum somatic hybrid plants were successfully transferred to soil and grown to maturity, representing the first flowering intergeneric somatic hybrids recovered in Gramineae.  相似文献   

4.
The aim of our work is to investigate the changes in phenolic level, PAL activity and heat production rate induced during pre-hardening at 12°C and cold acclimation at 2°C of the forage grasses Festulolium, meadow fescue, tall fescue and Italian ryegrass in relation to their resistance to snow mould caused by Microdochium nivale. Meadow fescue and tall fescue were most resistant to M. nivale infection, while Italian ryegrass demonstrated the least resistance to this fungus inoculation. Festulolium, meadow fescue and tall fescue responded similarly to low temperature, while Italian ryegrass demonstrated considerable disturbance of energy balance and lower phenolic concentration, which could explain a higher susceptibility of the latter species to infection by M. nivale. The enhanced level of phenolic compounds, probably utilised for cell wall lignification as well as equilibrium of the metabolic activity observed in meadow fescue and tall fescue, is very important for both cold and pathogen-resistance mechanisms. The studied Festulolium cultivar ‘Felopa’, a hybrid of the Lolium multiflorum and Festuca pratensis genomes, was characterised by changes in biochemical parameters similar to the resistant meadow fescue and tall fescue.  相似文献   

5.
Changes in light quality occur naturally within a canopy when a plant grows from unshaded to shaded conditions, and the reverse occurs after a cut that reduces shading. These changes in light quality could be responsible for the variation in leaf elongation and appearance rates of grasses. The role of blue light in leaf growth was investigated in tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Lolium perenne L.). Leaf length was measured daily following a decrease or an increase in blue light to evaluate effects on duration of leaf growth, leaf elongation and the rate of leaf appearance rate. A reduction in blue light increased sheath length by 8 to 14% and lamina length by 6 to 12% for both species. These increases could be reversed by enrichment of blue light. With low blue light treatment, final leaf length was increased due to a greater leaf elongation rate. In tall fescue, but not in perennial ryegrass, this effect was coupled with a greater phyllochron and a longer duration of leaf elongation. Development of successive leaves on a tall fescue tiller were co-ordinated. A decrease in blue light increased the duration of elongation in the oldest growing leaf and also delayed the appearance of a new leaf, maintaining this co-ordination. We conclude that final leaf size and phyllochron for tall fescue can be significantly modified by blue light. Perennial ryegrass appeared less responsive, except for displaying longer sheaths and laminae in low blue light, as also occurred for tall fescue. We hypothesize that leaf length could be regulated by the quality of the light reaching the growing region itself.  相似文献   

6.
Swards of Brachiaria decumbens were burnt and the development of tillers emerging 5 (T5) or 10 (T10) days later was studied. The stages of raceme initiation, spikelet initiation, spikelet differentiation and inflorescence exsertion occurred in 50% of tillers c. 14.5, 21, 26.5 and 59 days after tiller emergence respectively. Growth of T5 tillers was faster than that of T10 tillers, and raceme initiation occurred when T5 tillers were slightly longer and heavier than T10 tillers, making the external identification of early development events unreliable. Attention is directed to the large variability in the development of tillers emerging on the same day and to the need for better synchrony of raceme initiation as a basis for increased uniformity of inflorescence exsertion.  相似文献   

7.
Little is known about interactions between seeds within theinflorescence of perennial ryegrass (Lolium perenneL.) and theireffect on final seed weight. These relations were investigatedin two glasshouse experiments using two genotypes, by reducingthe number of seeds in an inflorescence at anthesis. In thefirst experiment, entire spikelets were removed to study therelations between seeds in different spikelets. The effectson seed dry weight were not proportional to the number of spikeletsremoved. In one genotype, removal of two-thirds of the spikeletsincreased seed dry weight of the remaining seeds by 15%. Inthe other genotype, such treatment did not increase seed dryweight. In the second experiment, investigating seed interactionswithin a spikelet, either two proximal seeds or two centralseeds were maintained in a spikelet by removing the other ovulesin combination with no or 75% shading. Shading by 75% reducedseed dry weight by about 10%. In the unshaded treatment, seeddry weight was not affected by ovule removal. Under shading,the central seeds in a spikelet were about 12% heavier if theygrew alone, in contrast to the proximal seeds. The effects ofa reduction in seed number on seed dry weight were not relatedto the final nitrogen concentration of seeds. These experimentsshow that assimilate partitioning and the relationship betweenseeds in the inflorescence of perennial ryegrass are alreadylargely determined at anthesis; increasing seed yield by manipulationsafter anthesis is not feasible.Copyright 1998 Annals of BotanyCompany. Lolium perenne, perennial ryegrass, seed growth, seed interactions, shading, spikelet removal.  相似文献   

8.
9.
Long photoperiods provided in growth cabinets and consisting of a conventional extended photoperiod or of a ‘light-break’ in the middle of a long, dark period, generally increased leaf length and sometimes leaf width and consequently the rate of expansion of leaf surface, but decreased rate of leaf production and tillering in vegetative plants of S.37 cocksfoot (Dactylis glomerata L.), S.215 meadow fescue (Festuca pratensis Huds.) and S.24 perennial rye-grass (Lolium perenne L.) compared with short photoperiods. All plants received the same total amount of light each day. These effects were observed both in single plants and in plants grown close together to simulate sward conditions. The total dry weight of plant material was greater in long than in short photoperiods.  相似文献   

10.
Tall fescue EST-SSR markers with transferability across several grass species   总被引:26,自引:0,他引:26  
Tall fescue (Festuca arundinacea Schreb.) is a major cool season forage and turf grass in the temperate regions of the world. It is also a close relative of other important forage and turf grasses, including meadow fescue and the cultivated ryegrass species. Until now, no SSR markers have been developed from the tall fescue genome. We designed 157 EST-SSR primer pairs from tall fescue ESTs and tested them on 11 genotypes representing seven grass species. Nearly 92% of the primer pairs produced characteristic simple sequence repeat (SSR) bands in at least one species. A large proportion of the primer pairs produced clear reproducible bands in other grass species, with most success in the close taxonomic relatives of tall fescue. A high level of marker polymorphism was observed in the outcrossing species tall fescue and ryegrass (66%). The marker polymorphism in the self-pollinated species rice and wheat was low (43% and 38%, respectively). These SSR markers were useful in the evaluation of genetic relationships among the Festuca and Lolium species. Sequencing of selected PCR bands revealed that the nucleotide sequences of the forage grass genotypes were highly conserved. The two cereal species, particularly rice, had significantly different nucleotide sequences compared to the forage grasses. Our results indicate that the tall fescue EST-SSR markers are valuable genetic markers for the Festuca and Lolium genera. These are also potentially useful markers for comparative genomics among several grass species.Electronic Supplementary Material Supplementary material is available for this article at .  相似文献   

11.
Organogenesis in plants is controlled by meristems. Shoot apical meristems form at the apex of the plant and produce leaf primordia on their flanks. Axillary meristems, which form in the axils of leaf primordia, give rise to branches and flowers and therefore play a critical role in plant architecture and reproduction. To understand how axillary meristems are initiated and maintained, we characterized the barren inflorescence2 mutant, which affects axillary meristems in the maize inflorescence. Scanning electron microscopy, histology and RNA in situ hybridization using knotted1 as a marker for meristematic tissue show that barren inflorescence2 mutants make fewer branches owing to a defect in branch meristem initiation. The construction of the double mutant between barren inflorescence2 and tasselsheath reveals that the function of barren inflorescence2 is specific to the formation of branch meristems rather than bract leaf primordia. Normal maize inflorescences sequentially produce three types of axillary meristem: branch meristem, spikelet meristem and floral meristem. Introgression of the barren inflorescence2 mutant into genetic backgrounds in which the phenotype was weaker illustrates additional roles of barren inflorescence2 in these axillary meristems. Branch, spikelet and floral meristems that form in these lines are defective, resulting in the production of fewer floral structures. Because the defects involve the number of organs produced at each stage of development, we conclude that barren inflorescence2 is required for maintenance of all types of axillary meristem in the inflorescence. This defect allows us to infer the sequence of events that takes place during maize inflorescence development. Furthermore, the defect in branch meristem formation provides insight into the role of knotted1 and barren inflorescence2 in axillary meristem initiation.  相似文献   

12.
Sadik , Sidki . (U. California, Davis.) Morphology of the curd of cauliflower. Amer. Jour. Bot. 49(3): 290–297. Illus. 1962.—The development of the curd and inflorescence of cauliflower, Brassica oleracea Linn., var. botrytis D.C., is described. The cultivars ‘Snowball M’ and ‘February-Early-March’ were studied. The curd has a nonfasciated and monopodial type of branching. Curd initiation of ‘Snowball M’ is not dependent on vernalization, but the curd of ‘February-Early-March’ and the floral primordia of both cultivars are initiated only after vernalization. Associated with flowering is the disruption of the curd by the elongation of some of the inflorescence branches. The initiation of leaves, branches, and floral primordia follows a 5 + 8 phyllotaxy throughout all stages of development. This system of phyllotaxy changes at the time of initiation of floral parts.  相似文献   

13.
Development of the mixed inflorescence in Zea diploperennis Iltis, Doebley & Guzman (Poaceae) Mixed inflorescences of diploperennial teosinte, which terminate the main branches of the plant, arise in the same fashion as tassel spikes. The apical meristem produces bracts in a decussate arrangement. A single axillary bud primordium is initiated in the axil of each bract. Growth of the bract is retarded as the bud enlarges and divides longitudinally into two separate spikelet primordia. The paired spikelets running in two ranks on either side of the inflorescence primordium produce the four-rowed condition typical of teosinte tasselS. In the transition region between male and female portions of the inflorescence, development of the pedicellate spikelet of each spikelet pair is arrested at an early ontogenetic stage. Continued growth of the sessile spikelet and associated rachis flaps destroy the remnants of the arrested spikelet in basal portions of the inflorescence. A similar abortion of the lower floret of the sessile spikelet results in a single pistillate floret per node at anthesis. These results provide further support for the hypothesis that a tassel-like mixed inflorescence of teosinte is ancestral to the maize ear.  相似文献   

14.
The “BF14/16×HF2/7” mapping population of meadow fescue (Festuca pratensis Huds.) was characterised for number of panicles produced by non-vernalised plants in the field, vernalisation requirement (number of weeks at 6°C and 8 h photoperiod), as well as days to heading, number of panicles and proportion of shoots heading after a 12 weeks vernalisation treatment. Quantitative trait loci (QTLs) were identified and compared to QTLs and genes related to the induction of flowering in cereals and grasses. A region on chromosome 1F affected days to heading and the proportion of shoots heading. Chromosome 4F appeared to have several genes with a strong effect on vernalisation requirement. The strongest effects were located in the proximal end of 4F and may correspond to the earliness per se (eps) QTL eps6L.2 in barley and a heading time QTL in perennial ryegrass. A part of the meadow fescue orthologue of VRN1 was sequenced and mapped to another region of 4F that also had a strong effect on vernalisation requirement. The proximal end of chromosome 5F had QTLs for days to heading and proportion of heading shoots. Syntenic regions in wheat and barley contain eps-loci. A QTL for number of panicles in the field and a QTL for proportion of heading shoots were present on chromosome 6. A region on 7F affected the variation in number of panicles among plants without a vernalisation requirement, and is syntenic to regions in perennial ryegrass, barley and rice containing orthologues of Arabidopsis thaliana CO.  相似文献   

15.
The molecular and genetic control of inflorescence and flower development has been studied in great detail in model dicotyledonous plants such as Arabidopsis and Antirrhinum . In contrast, little is known about these important developmental steps in monocotyledonous species. Here we report the analysis of the Zea mays mutant branched silkless1–2 (bd1–2) , allelic to bd1 , which we have used as a tool to study the transition from spikelet to floret development in maize. Floret development is blocked in the female inflorescence (the ear) of bd1–2 plants, whereas florets develop almost normally in the male inflorescence (the tassel). Detailed phenotypic analyses indicate that in bd1–2 mutants ear inflorescence formation initiates normally, however, the spikelet meristems do not proceed to form floret meristems. The ear spikelets, at anthesis, contain various numbers of spikelet-like meristems and glume-like structures. Furthermore, growth of branches from the base of the ear is often observed. Expression analyses show that the floral-specific MADS box genes Zea mays AGAMOUS1 ( ZAG1 ), ZAG2 and Zea mays MADS 2 ( ZMM2 ) are not expressed in ear florets in bd1–2 mutants, whereas their expression in tassel florets is similar to that of wild type. Taken together, these data indicate that the development from spikelet to floret meristem is differentially controlled in the ear and tassel in the monoecious grass species Zea mays , and that BRANCHED SILKLESS plays an important role in regulating the transition from spikelet meristem to floral meristem during the development of the female inflorescence of maize.  相似文献   

16.
Summary A study was made of intra-species differences in sodium uptake by timothy (Phleum pratense) and meadow fescue (Festuca pratensis), two pasture grasses that are generally known as being low in Na-content compared with perennical ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata). Na22 was used with NaNO3 as a tracer in a fertilizer experiment on seedlings grown on trays placed on benches in the greenhouse. With timothy significant clonal differences in Na-uptake varied from one half to the double, but the Na-contents were still appreciably lower than in ryegrass or cocksfoot.  相似文献   

17.
CAMARA-HERNANDEZ J. & GAMBINO, S., 1991. Early ontogenetic development of the pistillate inflorescence in a diploid perennial teosinte (Zea diploperennis , Poaceae). The early ontogeny of pistillate inflorescences of %ea diploperennis in plants grown at the latitude of Buenos Aires, Argentina, is investigated using the scanning electron microscope. The pattern of development of the inflorescence is similar to that in staminate and mixed inflorescences, starting with the formation of a pair of spikelets from a common branch primordium initiated in the axil of a bract on the ear axis. This bract arrests its development and aborts early. After initiation of an outer glume on both spikelet primordia, the pedicellate spikelet arrests its growth and aborts resulting in the mature inflorescence having two rows of solitary spikelets arranged distichally. This is significantly different from the pattern observed by other authors in plants grown in different environments (such as in natural populations in Mexico).  相似文献   

18.
Suspension cultures from mature embryo-derived compact callus were initiated in seven meadow fescue (Festuca pratensis Huds.) cultivars. Four to six months after initiation, embryogenic suspension cultures with a moderate growth rate were established from three of them (cvs. Barmondo, Belimo and Leopard). These suspension cultures showed the capacity, maintained over six months, to regenerate green plants which could be grown to maturity under greenhouse conditions.Morphogenic suspension cultures from single genotypes of three F. pratensis cultivars (cvs. Barmondo, Belimo and Leopard) yielded large numbers of protoplasts, which upon culture in agarose beads using nurse cells formed microcalli with an overall plating efficiency in the range of 10-3 to 10-4. Mature plants were reproducibly regenerated and established in soil, from such protoplasts during a period of six months. The regeneration of fertile plants from protoplasts derived from suspension cultures of meadow fescue and its implications on gene transfer technology for this species are discussed.Abbreviations 2,4-D 2,4-dichlorophenoxy-acetic acid.  相似文献   

19.
The response of grassland soil bacterial community characteristics to different grazing intensities is central ecological topics. However, the underlying mechanisms between bacterial abundance, diversity index, and grazing intensity remain unclear. We measured alpine meadow soil bacterial gene richness and diversity index under four grazing intensities using 16S rDNA sequence analysis on the Tibetan Plateau. The results suggest that extreme grazing significantly decreased alpine meadow both bacterial gene abundance and diversity index (p < .05). The lowest operational taxonomic unit numbers were 3,012 ± 447 copies under heavy grazing in the growing season. It was significantly lower than heavy grazing with approximately 3,958 ± 119 copies (p < .05). The Shannon index for medium and high grazing grassland bacterial diversity was slightly higher than for light grazing in the growing season. Furthermore, the lowest index was approximately 9.20 ± 0.50 for extreme grazing of grassland in the growing season. The average bacterial gene abundance and diversity index in the dormancy period were slightly higher than that in the growing season. Soil bulk density, pH, ammonium, and nitrate nitrogen were the main positive factors driving grazed grassland bacterial communities. Our study provides insight into the response of alpine meadows to grazing intensity, demonstrating that moderate grazing increases bacterial community diversity in grazed grasslands.  相似文献   

20.
The presented work was conducted on seedlings of spring barley and meadow fescue which differ in the degree of sensitivity to leaf spot pathogen Bipolaris sorokiniana (Sacc.) Shoem. The seedling reaction to inoculation with mycelium and conidia was examined in glasshouse conditions on the basis of respiration intensity and heat production. The leaf respiration was measured using Clark-type electrode, while heat emission was evaluated by means of isotermic microcalorimeter. The measurements were performed after 1, 3, 6, 10, 24, 48, 72, 168 and 240 hours since the inoculation moment. Leaves of meadow fescue were characterized by the most intense respiration at the 6th hour, while barley leaves at the 24th and 72nd hour after inoculation. In the case of meadow fescue the greatest heat production was noted in the period between 24 and 168 hours after inoculation. Simultaneously, at the 48th hour the smallest rate of respiration was observed. Barley leaves emitted the greatest amount of heat only in the first 3 hours of the pathogenesis. In these hours the smallest respiration rate was noted. The observed, opposing reaction of respiration intensity and heat emission in the infected seedlings of both species may illustrate a disorder in metabolic processes in plants during pathogenesis. The plants studied differed in the time of their reaction to pathogen attack: barley responded earlier in heat production, while fescue extended respiration rate in the first hours after inoculation. This is clearly observable, when coefficients of metabolic inefficiency (heat rates per mole O2) are compared. In the case of barley the highest rates were noticed just after inoculation, whereas in fescue at the 48th hour. In both species attack of pathogen caused high metabolic efficiency.  相似文献   

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