Successful crosses between Festuca arundinacea Schreb. and Dactylis glomerata L.

Summary Five F₁ plants have been obtained after extensive crossing between different ecotypes or varieties of Festuca arundinacea Schreb. and Dactylis glomerata L. The success did not appear to depend on specific treatments (spraying with -aminocaproic acid or gibberellic acid or pre-pollination with killed pollen from the seed parent), but the crossability is limited to exceptional plants.F₁ hybrids showed characteristics of both the parents. In four hybrids various developmental disturbances were observed (low viability, aneusomaty, absence of development of inflorescences). Only one hybrid consistently showed 2n=35 chromosomes, good viability and growth, however, it was sterile. After clonal propagation, attempts for polyploidization were started.     

Hydraulic architecture and water flow in growing grass tillers (Festuca arundinacea Schreb.)

The water relations and hydraulic architecture of growing grass tillers (Festuca arundinacea Schreb.) are reported. Evaporative flux density, E (mmol s^?1 m^?2), of individual leaf blades was measured gravimetrically by covering or excision of entire leaf blades. Values of E were similar for mature and elongating leaf blades, averaging 2·4 mmol s^?1 m^?2. Measured axial hydraulic conductivity, K_h (mmol s^?1 mm MPa^?1), of excised leaf segments was three times lower than theoretical hydraulic conductivity (K_t) calculated using the Poiseuille equation and measurements of vessel number and diameter. K_t was corrected (K_t*) to account for the discrepancy between K_h and K_t and for immature xylem in the basal expanding region of elongating leaves. From base to tip of mature leaves the pattern of K_t* was bell‐shaped with a maximum near the sheath–blade joint (≈ 19 mmol s^?1 mm MPa^?1). In elongating leaves, immature xylem in the basal growing region led to a much lower K_t*. As the first metaxylem matured, K_t* increased by 10‐fold. The hydraulic conductances of the whole root system, (mmol s^?1 MPa^?1) and leaf blades, (mmol s^?1 MPa^?1) were measured by a vacuum induced water flow technique. and were linearly related to the leaf area downstream. Approximately 65% of the resistance to water flow within the plant resided in the leaf blade. An electric‐analogue computer model was used to calculate the leaf blade area‐specific radial hydraulic conductivity, (mmol s^?1 m^?2 MPa^?1), using , K_t* and water flux values. values decreased with leaf age, from 21·2 mmol s^?1 m^?2 MPa^?1 in rapidly elongating leaf to 7·2 mmol s^?1 m^?2 MPa^?1 in mature leaf. Comparison of and values showed that ≈ 90% of the resistance to water flow within the blades resided in the liquid extra‐vascular path. The same algorithm was then used to compute the xylem and extravascular water potential drop along the liquid water path in the plant under steady state conditions. Predicted and measured water potentials matched well. The hydraulic design of the mature leaf resulted in low and quite constant xylem water potential gradient (≈ 0·3 MPa m^?1) throughout the plant. Much of the water potential drop within mature leaves occurred within a tenth of millimetre in the blade, between the xylem vessels and the site of water evaporation within the mesophyll. In elongating leaves, the low K_t* in the basal growth zone dramatically increased the local xylem water potential gradient (≈ 2·0 MPa m^?1) there. In the leaf elongation zone the growth‐induced water potential difference was ≈ 0·2 MPa.     

Drought survival in Dactylis glomerata and Festuca arundinacea under similar rooting conditions in tubes

Drought survival in perennial forage plants involves different adaptative responses such as delay of dehydration through water uptake, limitation of water loss and tolerance of tissues to dessication. To compare the importance of these responses in contrasting cultivars of forage grasses at the whole plant level, we carried out two experiments under glasshouse conditions. Plants of cocksfoot (Dactylis glomerata L.) cultivars, cvs. Currie, Medly (both of Mediterranean origin) and Lutetia (of continental origin), and of tall fescue (Festuca arundinacea L.) cv. Centurion (Mediterranean) were grown in 60 cm-deep cylinders to eliminate the effect of differences of root depth on water availability whilst allowing severe drought to be imposed at a realistic rate. In both experiments, the cvs. were ranked similarly for plant survival, with high mortality for Centurion, low for the Mediterranean cocksfoots Currie and Medly, and intermediate for Lutetia. These differences could not be ascribed to water use during most of the drought period since water uptake and decrease in leaf extension were not significantly different between species and cultivars. However, resistant cvs. of cocksfoot were able to extract water for a longer period and at a lower soil water potential (s) than other cvs. The critical s at plant death was –3.8 and –3.6 MPa for Medly and Currie and –3.0-,–2.6 MPa for Lutetia and Centurion. Moreover, at a low soil water reserve (15–2%), membrane stability and water content were maintained for longer in enclosed immature leaf bases of cocksfoots cultivars, whereas the fescue Centurion exhibited accelerated lamina senescence and steady increase of membrane damage in surviving tissues. Therefore, it is proposed that the drought resistance of tall fescue in the field can mainly be ascribed to its ability to develop a deep root system. In cocksfoot, dehydration tolerance in surviving tissues and the ability of roots to extract water at low soil water potentials may, in addition to root depth, contribute significantly to plant survival under severe drought.     

Genetic variability of mineral concentrations in Festuca arundinacea Schreb.

Summary Nine randomly chosen clones of tall fescue (Festuca arundinacea Schreb.) were mated in all possible combinations to determine the nature of genetic variation for Mg, Ca, K, and P concentrations in a broad genetic base population. General combining ability mean squares were significant for most variables, whereas specific combining ability mean squares were not significant in most instances indicating that additive genetic variance was more important. Genotype x year interactions were significant for most variables, suggesting that selection should be evaluated over many environments. Broad-sense heritability estimates based on parental and progeny variance components were generally high for P, K, Ca, and Mg but low for the ratio K/(Ca + Mg). Narrow-sense heritabilities for these minerals were close to the broad sense values since the additive genetic variance was the largest component of the total genetic variation. Correlations between mineral concentrations and herbage dry matter yield were low. It was concluded that adequate genetic variation exists to improve mineral concentration without altering herbage dry matter yields.Journal Series no. 5886     

Comparative studies on desiccation resistance in leaves ofDactylis glomerata L. andFestuca arundinacea Schreb

Festuca arundinacea Schreb. andDactylis glomerata L., which differ in their ecological requirements toward moisture conditions also express different levels of desiccation tolerance.F. arundinacea was less resistant to severe water stress, showing lower ability to avoid and to tolerate desiccation (according to Levitt’s terminology, 1972). Growth stage of the leaves had no influence on the level of water deficits developed under the field conditions. It is concluded that adaptation ofF. arundinacea to growth in well watered environments might be associated with a decrease of desiccation resistance of its tissue.     

Influence of polishing and abrasion on the diffusive conductance of leaf surface of Festuca arundinacea Schreb.

Abstract Leaf surfaces of Festuca arundinacea Schreb. were subjected to controlled polishing and abrasion on a test-bed designed to simulate components of abrasive wind damage. Both treatments substantially increased the leaf surface conductance, particularly the polishing treatment. Scanning electron micrographs of cryo-fixed leaf surfaces showed displacement and smoothing of the epicuticular waxes, damage to the cuticle, collapse of epidermal cells and fracture of trichomes. The importance of the epicuticular waxes in determining leaf diffusivity and permeability is discussed.     

Temperature Effects upon Inflorescence and Seed Development in Tall Fescue (Festuca arundinacea Schreb.)

The effects of three temperatures 15, 20, and 25 °C uponinflorescence and seed development in tall fescue (Festuca arundinaceaSchreb) between inflorescence emergence and seed maturity werestudied. Increasing temperature over this range reduced culmlength and the number of florets per spikelet, hastened theonset of anthesis and pollen release, increased relative growth-rateof the florets 9 days after peak anthesis, reduced the periodof seed development and 1000 seed weight No large effects oftemperature upon the percentage of florets setting seed werefound. The practical implications of these results are discussed.     

The Effect of Wind on Grasses II. Mechanical Damage in Festuca arundinacea Schreb

After a period of exposure to wind in a wind tunnel, two aspectsof the resulting mechanical damage in Festuca arundinacea Schreb.var. S170 were examined. These were the frequency of occurrenceof transverse fold lines and the microscopic nature of leafabrasion marks. Transverse fold lines were found to be of morefrequent occurrence in wind-exposed plants. A stereoscan electronmicroscope was used to show the severe damage to the leaf surfacethat can result from leaves rubbing over each other. Some possibleconsequences of such damage are discussed.     

Stage Development and Flowering in Dactylis glomerata L.

The results of pilot experiments lead to the conclusion thatD. glomerata exhibits a number of developmental stages: firstly,a juvenile stage during which the plant is insensitive to environmentalconditions which later stimulate flowering; secondly, an inductivestage, when the plant responds to periodic exposure to darknessat the conclusion of which it is fully induced or ripe to flower,and finally, a post-inductive stage during which inflorescencesare initiated and undergo further development; these are long-dayprocesses. In four populations studied the juvenile stage lasts about fiveweeks. In north European material daily exposure to seven hoursof darkness is near the minimum for induction although thereis considerable within-population variation. Further, it appearsthat the daily dark requirement becomes less as the plant ages. Comparisons are made of the flowering behaviour of D. glomerataand Lolium perenne. The differences between these species resultfrom the presence of a juvenile stage in Dactylis and the possibilityof satisfying its inductive requirement by long days. Inductionin Lolium requires short days or low temperature. The significance of these results is discussed in the lightof previous work on the environmental control of flowering inherbage grasses. The existence of three developmental stagescan explain the wide differences in interpretation of the floweringrequirements of Dactylis previously held. The possible evolutionof flowering requirements is also discussed.     

The 'hydrology' of leaves: co-ordination of structure and function in temperate woody species

The hydraulic conductance of the leaf lamina (K_lamina) substantially constrains whole‐plant water transport, but little is known of its association with leaf structure and function. K_lamina was measured for sun and shade leaves of six woody temperate species growing in moist soil, and tested for correlation with the prevailing leaf irradiance, and with 22 other leaf traits. K_lamina varied from 7.40 × 10^?5 kg m^?2 s^?1 MPa^?1 for Acer saccharum shade leaves to 2.89 × 10^?4 kg m^?2 s^?1 MPa^?1 for Vitis labrusca sun leaves. Tree sun leaves had 15–67% higher K_lamina than shade leaves. K_lamina was co‐ordinated with traits associated with high water flux, including leaf irradiance, petiole hydraulic conductance, guard cell length, and stomatal pore area per lamina area. K_lamina was also co‐ordinated with lamina thickness, water storage capacitance, 1/mesophyll water transfer resistance, and, in five of the six species, with lamina perimeter/area. However, for the six species, K_lamina was independent of inter‐related leaf traits including leaf dry mass per area, density, modulus of elasticity, osmotic potential, and cuticular conductance. K_lamina was thus co‐ordinated with structural and functional traits relating to liquid‐phase water transport and to maximum rates of gas exchange, but independent of other traits relating to drought tolerance and to aspects of carbon economy.     

Volatile compounds of endophyte-free and infected tall fescue (Festuca arundinacea Schreb.).

Volatile compounds produced by intact plants and ground leaf tissue from endophyte-infected (E+) and endophyte-free (E-) tall fescue (Festuca arundinacea Schreb.) were collected by a purge-and-trap procedure and analyzed by gas chromatography/mass spectrometry The volatile compound profile from ground leaf tissue was similar between E+ and E- clonal plants; however, the sheaths of E+ clonal plants produced higher levels of 1-octen-3-ol, a characteristic volatile compound derived from lipid peroxidation in fungi, which was absent in E- clonal plants. Intact plants produced fewer volatiles than macerated leaves. At 25 degrees C, (Z)-3-hexen-1-ol acetate was the most abundant compound, accounting for 77 and 89% of the total volatile emission from E+ and E- plants, respectively. Higher temperature (32 degrees C) significantly reduced the production of (Z)-3-hexen-1-ol acetate. Nonanal was the most abundant compound at 32 degrees C accounting for 52 and 45% of the total volatile emission from E+ and E- plants. Treatment of E+ and E- plants with jasmonic acid (JA) dramatically altered the volatile compound profile. The levels of (E)-beta-ocimene increased more than 200-fold and accounted for at least 43% of the total volatile emission. Although the presence of endophyte resulted in some qualitative and quantitative differences in the production of volatile compounds, they are unlikely to account for the differences in insect resistance between E+ and E- plants. Nevertheless, the production of a unique spectrum of volatiles after JA treatment may represent a significant plant-based defense response in tall fescue that is independent of endophyte.     

Detection of Kestoses and Kestose-Related Oligosaccharides in Extracts of Festuca arundinacea, Dactylis glomerata L., and Asparagus officinalis L. Root Cultures and Invertase by C and H Nuclear Magnetic Resonance Spectroscopy

A previous study (KL Forsythe, MS Feather [1989] Carbohydr Res 185: 315-319) showed that ¹³C nuclear magnetic resonance spectroscopy can be used to detect and identify mixtures of 1-kestose and neokestose after conversion to the acetate derivatives. In this study, unequivocal assignments are made for the anomeric carbon and proton signals for the above two trisaccharide acetates as well as for 6-kestose hendecaacetate and for nystose tetradecaacetate (a 1-kestose-derived tetrasaccharide). A number of oligosaccharide fractions were isolated from several plant species, converted to the acetates, and nuclear magnetic resonance spectra obtained. Using the above reference data, the following information was obtained. The trisaccharide fraction from Dactylis glomerata L. stem tissue and Asparagus officinalis L. roots contain both 1-kestose and neokestose, and the tetrasaccharide fractions contain three components, one of which is nystose. Penta- and hexasaccharide acetates were also isolated from A. officinalis L. roots and were found to contain, respectively, four and at least five components. All components of both of the above species appear to contain a kestose residue and to be produced by the sequential addition of fructofuranosyl units to these. The trisaccharide fraction from Festuca arundinacea is complex, and contains at least five different components, two of which appear to be 1-kestose and neokestose.     

Plantlet formation from cultured inflorescences of Dactylis glomerata L.

The objective of this study was to demonstrate plantlet formation from cultured mature inflorescences of field-grown orchardgrass (Dactylis glomerata L.) plants. Whole tillers were collected and maintained in the dark at 4°C for either 19 or 25 days before panicle sections were plated on a Linsmaier and Skoog (LS) or Schenk and Hildebrandt (SH) agar medium containing 2,4-D. Generally, better results for both cell proliferation and plantlet formation were obtained with 1) large explants (many florets) on 9.1 μM 2,4-D compared to small explants (few florets) on 1.0 μM 2,4-D, 2) SH rather than LS medium and 3) when tillers were pretreated at 4°C for 25 days rather than 19 days. Chromosome counts of basal leaf cells in 94 regenerated plants showed that no plants possessed the gametic chromosome number of n=14.     

The Effects of Shaking on the Growth and Water Relations of Festuca arundinacea Schreb

The extension growth of Festuca arundinacea was reduced by shaking,and the leaves formed during shaking were thinner and narrowerthan the controls. The response to shaking was modified by thenutritional status of the plant — shaken plants took upmore phosphorus from a phosphorus deficient soil than the controlsand this advantage seemed to offset the influence of shaking. Shaken plants displayed a higher stomatal conductance and alower water potential than the controls, though it was consideredthat the effect of shaking could not be attributed entirelyto differences in water potential. Festuca arundinacea Schreb., water potential, stomatal conductance, phosphorus, shaking     

Metabolism and subcellular distribution of anthracene in tall fescue (Festuca arundinacea Schreb.)

Aim

Understanding the uptake processes of organic contaminants by plants is essential when assessing crop contamination and subsequent human exposure. Unfortunately, limited information is available on plant metabolism and subcellular distribution of polycyclic aromatic hydrocarbons (PAHs), a group of highly toxic organic contaminants with carcinogenic, mutagenic, and teratogenic properties. Thus we seek to investigate the metabolism and intracellular distribution of PAH in tall fescue (Festuca arundinacea Schreb.).

Methods

This work was conducted utilizing greenhouse hydroponical experiments. Seedlings of tall fescue were firstly cultured in half-strength Hoagland solution with anthracene (ANT). Then treated plants were removed from the ANT-spiked solution, and transplanted into solutions free of ANT. After 0–16 days, the seedlings were sampled and prepared for ANT analysis. Seedlings were washed using Milli-Q water and then separated into different parts to measure ANT distributions at the subcellular level.

Results

ANT concentrations and dissipation amounts in root and shoot of tall fescue decreased in 0–16 days after transplantation from an ANT-spiked culture solution to a solution free of PAH, revealing ANT metabolism in the plant. The accumulation of the examined primary metabolites of ANT, i.e., anthrone and anthraquinone, against time also supported plant metabolism of ANT. About 10 % of ANT resided in the plants at 8–16 days due to the formation of ANT-bound residues with plant tissues. ANT concentrations in the cell walls and organelles of plant roots and shoots decreased significantly during the 16-day period. Cell walls and organelles were the dominant storage compartments for ANT and anthraquinone in plants at 16 days, whereas the distribution of anthrone at 16 days in root cells was ordered as cell organelles >cell soluble fraction >cell wall and in shoot cells as cell soluble fraction >> cell organelle ? cell wall. Although the organelle content is smaller, the concentrations of ANT and metabolites in the organelle fraction were much higher than those in cell walls.

Conclusions

This was a primary investigation into the metabolism and intracellular distribution of PAH in plant. We demonstrated the metabolism of ANT in tall fescue based on the observed reduced concentrations, dissipated amounts, and detected metabolites. ANT and its metabolites were distributed into the cell water-soluble fraction, cell walls, and organelles. Results of this work will enhance the understanding of PAH transfer and transformation in plants and will be valuable for risk assessments of plant contamination at polluted sites.     

Genetic regulation of diploid-like chromosome pairing in the hexaploid species,Festuca arundinacea Schreb. and F. rubra L. (Gramineae)

The basis of diploid-like chromosome pairing in hexaploid (2n=6x=42) Festuca arundinacea Schreb. and hexaploid F. rubra L. has been investigated. On the combined evidence derived from chromosome pairing in some euploid (2n=42) and monosomic (2n=41) hybrids from a diallel set of crosses between ten geographically diverse ecotypes of tall fescue, intergeneric hybrids involving tall fescue as well as red fescue, and euploid (2n=56) and aneuploid (2n=52, 53, 54, 55) amphiploids between Lolium multiflorum and F. arundinacea, it is concluded that diploid-like meiosis in these hexaploid species as well as in other natural polyploid species of Festuca is under genetic control. It is further inferred that this diploidizing gene(s) system must at least be disomic in dosage to be effective in suppressing homoeologous pairing and, therefore, had no influence upon pairing in haploid complements of the hybrids, i.e., it is haplo-insufficient or hemizygous-ineffective. — It has also been shown that sterility in hybrids between some geographically isolated ecotypes of tall fescue results from irregular meiosis due to the breakdown of the regulatory mechanism, rather than from chromosomal differentiation of the parental ecotypes as widely believed so far. The evolutionary significance of such a gene-repressing effect of certain genotypes or genes is indicated. — It is further suggested that the hemizygous ineffectiveness of the genetic control of bivalent pairing is of evolutionary significance and could have major implications on the cytogenetic relationships and the breeding of the entire Lolium-Festuca complex.