The proper timing of flowering, which is key to maximize reproductive success and yield, relies in many plant species on the coordination between environmental cues and endogenous developmental ...programs. The perception of changes in day length is one of the most reliable cues of seasonal change, and this involves the interplay between the sensing of light signals and the circadian clock. Here, we describe a
mutant allele of the evening complex protein EARLY FLOWERING 3 (ELF3). We show that the
mutant flowers more rapidly than wild type plants in short days as well as under longer photoperiods but, in very long (20 h) days, flowering is equally rapid in
and wild type. Furthermore, flowering in the
mutant is still sensitive to vernalization, but not to ambient temperature changes. Molecular analyses revealed that the expression of a short-day marker gene is suppressed in
grown in short days, and the expression patterns of clock genes and flowering time regulators are altered. We also explored the mechanisms of photoperiodic perception in temperate grasses by exposing
plants grown under a 12 h photoperiod to a daily night break consisting of a mixture of red and far-red light. We showed that 2 h breaks are sufficient to accelerate flowering in
under non-inductive photoperiods and that this acceleration of flowering is mediated by red light. Finally, we discuss advances and perspectives for research on the perception of photoperiod in temperate grasses.
Aim Successful colonization after long-distance dispersal (LDD) depends on the availability of suitable habitats and competitive ability. In this study, we address the hypothesis that two widely ...distributed sister grass lineages (broad- and fine-leaved Loliinae; hereafter BL and FL) that differ in their habitat requirements and competitive ability also differ in their biogeographic history, with particular reference to LDD. Location Global. Methods We reconstructed a comprehensive phylogeny of Loliinae, based on nuclear and plastid markers and estimated divergence times using fossil calibrations. Biogeographical events were estimated using analysis of range evolution, comparing different models. Numbers and rates of dispersals were estimated for BL and FL using stochastic mapping with best-performing and baseline biogeographical models, and examined for correlation with distance, disjunction type, and phenotypic syndrome. Results The most recent common ancestor of Loliinae likely split at the Oligocene-Miocene transition (22.50 ± 3.95 Ma), pre-dating previous estimates, whereas the ancestors of the BL and FL Loliinae likely began to diversify in the Early Miocene (18.91 ± 4.15 and 17.50 ± 3.50 Ma, respectively). A model of range evolution integrating founder events and scaling of dispersal by shortest distance between areas performed best amongst a set of alternative models and recovered a mean of 83 dispersal events in Loliinae. Overall dispersal rates were significantly higher in BL than in FL. Per-route dispersal rates showed a significant negative exponential relationship to shortest distance but were not affected by phenotypic syndrome or disjunction type. Main conclusions Loliinae originated in the Northern Hemisphere and evolved through recurrent LDDs. Higher competitive ability, potentially related to the broad-leaved syndrome (i.e. tall strong-rhizomatous plants, long-living individuals, occupancy of more stable habitats), may explain higher observed dispersal rates in BL compared with FL Loliinae. However, the dominant factor impacting dispersal in both BL and FL Loliinae is the distance between suitable areas.
Perception of seasonal cues is critical for reproductive success in many plants. Exposure to winter cold is a cue that can confer competence to flower in the spring via a process known as ...vernalization. In certain grasses, exposure to short days is another winter cue that can lead to a vernalized state. In
, we find that natural variation for the ability of short days to confer competence to flower is due to allelic variation of the
(
) paralog
(
). An active
allele is required for the acquisition of floral competence, demonstrating a novel role for a member of the
family of genes. Loss of the short-day vernalization response appears to have arisen once in
and spread through diverse lineages indicating that this loss has adaptive value, perhaps by delaying spring flowering until the danger of cold damage to flowers has subsided.
The majority of New Zealand dairy goat farmers utilise cultivated green-fed fodder dominated by perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), but evidence from other ...ruminant species suggests that milk production may be improved when using a more diverse array of species within the green fodder. The aim of this experiment was to determine whether feeding lactating dairy goats a mixed-species green fodder (MF, consisting of perennial ryegrass, timothy (Phleum pratense L.), prairie grass (Bromus willdenowii Kunth), white clover, red clover (Trifolium pratense L.), lucerne (Medicago sativa L.), chicory (Cichorium intybus L.) and plantain (Plantago lanceolata L.) improves dietary intake, milk yield and composition compared with a standard ryegrass and white clover green fodder (SF). Thirty-six mid-lactation goats were housed indoors in pairs and split into two groups (A and B). The trial was split into three periods - firstly a uniformity period of 6 days, in which all goats were fed a combination of both green fodder types, followed by two treatment periods (P1 and P2) of 12 days, respectively. For P1, group A was fed MF and group B was fed SF, and then the group diets were switched for P2. Goats fed MF had 13% greater dry matter intake and 7% greater milk yield than goats fed SF. In addition, the milk protein and fat concentration of goats fed MF were 4% greater than for those fed SF, whereas there was no effect on milk lactose concentration. There was no treatment effect on the levels of protein, glucose, urea or non-esterified fatty acids in the blood of the goats. An effect of green fodder type on milk fat profile was demonstrated, with proportions of pentadecylic acid (C15:0), cis-vaccenic acid (C18:1 c11), linoleic acid (C18:2 n6) and α-linolenic acid (C18:3 n3) being increased in response to MF consumption. In contrast, iso-C15 and iso-C17 proportions were lesser. In summary, this study demonstrated that goats fed MF increased green fodder intake and milk production compared with goats fed SF. The green fodder type affected the fatty acid profile of goat's milk, with MF increasing the levels of beneficial polyunsaturated omega fatty acids (linoleic and α-linolenic acids).
Adaptation to temperate environments is common in the grass subfamily Pooideae, suggesting an ancestral origin of cold climate adaptation. Here, we investigated substitution rates of genes involved ...in low-temperature-induced (LTI) stress responses to test the hypothesis that adaptive molecular evolution of LTI pathway genes was important for Pooideae evolution.
Substitution rates and signatures of positive selection were analyzed using 4330 gene trees including three warm climate-adapted species (maize (Zea mays), sorghum (Sorghum bicolor), and rice (Oryza sativa)) and five temperate Pooideae species (Brachypodium distachyon, wheat (Triticum aestivum), barley (Hordeum vulgare), Lolium perenne and Festuca pratensis).
Nonsynonymous substitution rate differences between Pooideae and warm habitatadapted species were elevated in LTI trees compared with all trees. Furthermore, signatures of positive selection were significantly stronger in LTI trees after the rice and Pooideae split but before the Brachypodium divergence (P < 0.05). Genome-wide heterogeneity in substitution rates was also observed, reflecting divergent genome evolution processes within these grasses.
Our results provide evidence for a link between adaptation to cold habitats and adaptive evolution of LTI stress responses in early Pooideae evolution and shed light on a poorly understood chapter in the evolutionary history of some of the world's most important temperate crops.
Members of the core pooids represent the most important crops in temperate zones including wheat, barley, and oats. Their importance as crops is largely due to the grain, particularly the storage ...capabilities of the endosperm. In this study, a comprehensive survey of grain morphology and endosperm organization in representatives of wild and cultivated species throughout the core pooids was performed. As sister to the core pooid tribes Poeae, Aveneae, Triticeae, and Bromeae within the Pooideae subfamily, Brachypodium provides a taxonomically relevant reference point. Using macroscopic, histological, and molecular analyses distinct patterns of grain tissue organization in these species, focusing on the peripheral and modified aleurone, are described. The results indicate that aleurone organization is correlated with conventional grain quality characters such as grain shape and starch content. In addition to morphological and organizational variation, expression patterns of candidate gene markers underpinning this variation were examined. Features commonly associated with grains are largely defined by analyses on lineages within the Triticeae and knowledge of grain structure may be skewed as a result of the focus on wheat and barley. Specifically, the data suggest that the modified aleurone is largely restricted to species in the Triticeae tribe.
Four Polwarth×Texel wethers (30±1.8kg body weight), fitted with a chronic rumen catheter and duodenal cannulae, housed in metabolic cages and offered ryegrass (Lolium multiflorum Lam) ad libitum were ...used in a 4×4 Latin Square experiment to evaluate the effects of infusing Acacia mearnsii tannin extract on intake, digestion and nutrients supply. Treatments consisted of no tannin (0) or intraruminal infusion of a tannin extract solution in a final volume that allowed for a tannin extract concentration of 20, 40 or 60g/kg of dry matter (DM) intake. Intake and total digestibility of organic matter (OM), neutral detergent fiber (NDF) and N compounds linearly reduced (P≤0.05) at increased levels of tannin infusion. Urinary N excretion linearly decreased (P≤0.05) whereas the proportion of ingested N, which was retained was not affected by treatments. Duodenal flow of α-amino N was not affected by treatments whereas rumen microbial N entering the duodenum tended to linearly decreased (P=0.15) at increased levels of tannin infusion. Ruminal degradability of both OM and dietary N compounds linearly decreased (P<0.05) at increased levels of tannins. The efficiency of rumen microbial protein synthesis was not affected by treatments. In conclusion, the use of Acacia mearnsii tannin extract as feed supplement for wethers fed ryegrass, at rates from 20 to 60g/kg DM intake, does not affect the α-amino N supply at the duodenum whereas it shows a negative impact on energy intake.
Two experiments were conducted to evaluate the effects of species, cutting date and cutting interval on the concentration of fatty acids in temperate grasses. The first experiment compared eight ...species, harvested in late autumn and summer. Levels of individual fatty acids were distinctive for some species, with low levels of C18:1 in Dactylis glomerata L. and high levels of C18:2 in Phleum pratense L. Differences in individual fatty acids could not be used to differentiate fescues and ryegrasses. However, fatty acid profiles could be used to differentiate species when material was managed similarly (i.e. at the same cut). There were large species × cut interaction effects, showing that management factors will be as important as plant breeding in manipulating fatty acid levels. Cultivars belonging to one Lolium perenne L. gene pool were identified as having significantly higher α‐linolenic acid and total fatty acids in late‐season (November) material.
The second experiment compared three ryegrass species over a growing season, with three or five cuts. All species had high concentrations of fatty acids and a high proportion of α‐linolenic acid during vegetative growth (late April). Fatty acid levels declined markedly in all species after this date, recovering by autumn. Kunth Lolium multiflorum Lam. and Lolium × boucheanum had higher levels of total fatty acids and α‐linolenic acid in the early and late season when compared with perennial ryegrass. Fatty acid levels (particularly C18:2 and C18:3) declined when the regrowth interval was extended from 20 to 38 d.
These studies demonstrate opportunities to change the composition of ruminant products through breeding and management of grasses for altered levels of fatty acids.
Display omitted
•The occurrence of Stowaway MITEs is described within the grass family.•A Poaceae organismal tree was used to analyze their evolutionary dynamics.•Stowaway MITEs were found in the ...fourth intron of the β-amylase gene.•Similar MITEs were also found in other nuclear genes in the BEP clade.•We hypothesize successive acquisitions, losses and HGT of MITEs in grasses.
The occurrence of Stowaway MITEs and their potential footprints in the grasses was assessed within an explicit phylogenetic framework. An organismal tree was used to analyze the distribution and evolutionary dynamics of these elements and their potential excision footprints in the fourth intron of the β-amylase gene and in other introns of several nuclear genes across the Poaceae. Megablast and discontiguous megablast searches in the Entrez nucleotide database were performed for the β-amylase, blz-1, dmc1, nuc, and xly genes MITEs. These elements and their potential footprints were distributed in introns and intergenic spacers of many other nuclear genes throughout the BEP lineages; however, they were absent in the studied PACCMAD lineages.
A plausible underlying dynamic of successive acquisitions and deletions of β-amylase Stowaway MITEs in the temperate grasses could be explained by three alternative hypotheses: (i) a single early acquisition of a palindrome element, similar to Tc1-Mariner, in the fourth intron of the β-amylase gene in the ancestor of the Pooideae, followed by multiple independent losses, (ii) multiple independent acquisitions of MITEs in non-related pooid lineages or (iii) different waves of acquisition of MITEs, followed by multiple losses and horizontal transfers in the temperate grasses. This last hypothesis seems to fit best with the evidence found to date.
In a 2-year field experiment, morphological development and measures of the nutritive value of herbage for livestock during primary growth in Meadow foxtail, Tall oatgrass, Cocksfoot, Perennial ...ryegrass and Yorkshire fog were investigated. All measured variables were affected significantly by both species and sampling date, and their interaction (P < 0·001), in the period of primary growth. Changes with time in mean stage weight for Meadow foxtail and Cocksfoot were different from the other species due to their indeterminate growth habits. Mean stage weight of Tall oatgrass and Yorkshire fog increased more rapidly than that of Perennial ryegrass with time. Changes in mean stage weight with time were described by linear, parabolic and sigmoid relationships. Crude protein (CP) concentration of herbage was higher for Cocksfoot and Meadow foxtail than for Perennial ryegrass. A parabolic relationship of CP concentration with time was typical for all the species. Concentrations of neutral-detergent fibre (NDF) and acid-detergent fibre (ADF) in herbage of the species differed most during the mid-period of primary growth. Their increases with time showed curvilinear (sigmoid and parabolic) relationships. Perennial ryegrass had lower concentrations of both NDF and ADF in herbage than the other species. Differences between the in vitro dry matter (DM) digestibility among the grasses increased in mid- and late periods of primary growth. Perennial ryegrass had higher values for in vitro DM digestibility but the difference from other species was small in the early period of primary growth and from cocksfoot in the late period of primary growth. In vitro DM digestibility showed, in most cases, a sigmoid and, in others, a linear decrease with time. Principal component analysis showed that perennial ryegrass and meadow foxtail were the most distinctive of the species in characteristics relating to morphological development and the nutritive value of herbage to livestock.
PDF
