Écologie et conservation du Mercure Arethusana arethusa (Denis & Schiffermüller, 1775) (Lépidoptère : Satyrinae) en Hauts-de-France

Le Mercure Arethusana arethusa (Denis & Schiffermüller, 1775) est un papillon qui, actuellement, n’est pas considéré comme menacé au sein des Listes rouges de France et d’Europe mais dont la distribution apparaît cependant en déclin. Le Conservatoire d’Espaces naturels des Hauts-de-France préserve deux des trois stations restantes en région. Sur la base de captures-marquages-recaptures et d’observations réalisées entre 2013 et 2019 sur les deux dernières populations du département de la Somme, nous avons étudié les paramètres démographiques, la mobilité des individus et leur utilisation des habitats. Les effectifs des populations ont été estimés avec une certaine précision puisque les marges d’erreur des estimations pour un niveau de confiance de 95 % étaient comprises entre 13 et 19 % selon les sites et les années. Des variations importantes d’effectifs, de plus de 50 %, ont été relevées entre certaines années et reflètent les tendances observées au niveau national dans le cadre des suivis des communautés de papillons de jours. Durant les trois années de suivis, la taille des populations est la plus élevée entre le 20 août et le 30 août. Le pic de vol des femelles intervient entre trois et six jours après celui des mâles et dure moins longtemps. Selon les sites et les années, la durée de vie moyenne est comprise entre 5,75 et 12 jours. Le sexe ratio mâles/femelles est de 1,18 en 2018 et de 1,28 en 2019. Si le contexte des sites étudiés (faible superficie, isolement) n’a pas permis d’étudier les capacités de dispersion d’A. arethusa, nous avons constaté que l’espèce se déplace peu dans ce contexte. La distance moyenne de déplacement est de 86,46 ± 6,34 m après au moins trois recaptures (n = 81). La distance maximale relevée entre deux captures est de 333 m. Les pelouses qui présentent une hauteur de végétation rase (6,57 ± 2,39 cm), avec des affleurements crayeux (8,21 ± 7,35 % par m²) et un recouvrement riche en Festuca ovina Gr. (22,6 ± 9,54 % par m²), constituent les habitats larvaires. Si ces milieux constituent également les habitats préférentiels des adultes, les pelouses plus fermées et jeunes ourlets calcicoles apparaissent complémentaires car elles offrent des ressources nectarifères qui sont faibles sur les pelouses les plus rases en période de vol du papillon. Nos résultats conduisent à faire émerger une question de conservation : comment faire coexister sur des petits espaces des dynamiques spatiales et temporelles de la végétation permettant d’assurer une disponibilité en ressources et en habitats nécessaires à l’accomplissement du cycle de vie d’A. arethusa ? Dans des paysages dominés par les grandes cultures, nous soulignons le rôle fonctionnel des prairies, jachères et bandes enherbées pour renforcer les populations en place et reconnecter les espaces fragmentés.

Bazı Buğdaygil Çim Türü ve Çeşitlerinin Adaptasyonları İle Çim Alan Özelliklerinin Belirlenmesi

Bu araştırma Şanlıurfa'da 2015-2016 yaz yetiştirme sezonunda, Harran Üniversitesi Osman Bey yerleşkesi Ziraat Fakültesi araştırma ve uygulama alanında yürütülmüştür. Araştırmada; kamışsı yumak (Festuca arundinaceae), İngiliz çimi (Lolium perenne), rizomsuz kırmızı yumak (Festuca rubra L. subsp. Commutate), rizomlu kırmızı yumak (Festuca rubra L. subsp. rubra), koyun yumağı (Festuca ovina), çayır salkım otu (Poa pratensis) materyal olarak kullanılmış, tesadüf blokları deneme desenine göre 3 tekerrürlü olacak şekilde kurulmuştur. Bu çalışmada; çim yaş ot verimi (kg/da), çim kuru ot verimi (kg/da), çıkış hızı (gün), kışa dayanıklılık (1-9), kaplama hızı (gün), kaplama derecesi (%), yaprak dokusu (1-9), kardeş sayısı (1-5) ve seyrekleşme derecesi (1-9) gibi karakterler incelenmiştir. Deneme bulgularına göre; Şanlıurfa ekolojik şartları için önerilebilecek sıcak mevsim çim tür çeşitlerinin pek çok özellik açısından kamışsı yumak (Festuca arundinaceae) Golden Gate çeşidinin kullanılması uygun olacaktır.

Transcriptional responses to water stress and recovery in a drought-tolerant fescue wild grass (Festuca ovina; Poaceae)

Water stress associated with drought-like conditions is a major factor limiting plant growth and impacts productivity of natural plant communities and agricultural crops. Molecular responses of plants to water stress have been studied most extensively in model species and crops, few of which have evolved natural drought tolerance. In the current study, we examined physiological and transcriptomic responses at multiple timepoints during increasing water stress and following initial recovery from stress in a drought-tolerant C3 species, Festuca ovina. Results demonstrated non-linear transcriptomic changes during increasing stress, but largely linear declines in physiological measurements during this same period. Transcription factors represented approximately 12.7% of all differentially expressed genes. In total, 117 F. ovina homologs of previously identified and molecularly characterized drought-responsive plant genes were identified. This information will be valuable for further investigations of the molecular mechanisms involved in drought tolerance in C3 plants.

When a foreign gene meets its native counterpart: computational biophysics analysis of two PgiC loci in the grass Festuca ovina

Duplicative horizontal gene transfer may bring two previously separated homologous genes together, which may raise questions about the interplay between the gene products. One such gene pair is the “native” PgiC1 and “foreign” PgiC2 in the perennial grass Festuca ovina. Both PgiC1 and PgiC2 encode cytosolic phosphoglucose isomerase, a dimeric enzyme whose proper binding is functionally essential. Here, we use biophysical simulations to explore the inter-monomer binding of the two homodimers and the heterodimer that can be produced by PgiC1 and PgiC2 in F. ovina. Using simulated native-state ensembles, we examine the structural properties and binding tightness of the dimers. In addition, we investigate their ability to withstand dissociation when pulled by a force. Our results suggest that the inter-monomer binding is tighter in the PgiC2 than the PgiC1 homodimer, which could explain the more frequent occurrence of the foreign PgiC2 homodimer in dry habitats. We further find that the PgiC1 and PgiC2 monomers are compatible with heterodimer formation; the computed binding tightness is comparable to that of the PgiC1 homodimer. Enhanced homodimer stability and capability of heterodimer formation with PgiC1 are properties of PgiC2 that may contribute to the retaining of the otherwise redundant PgiC2 gene.

Effect of four pre-planted cover crop species on weed control and population dynamics

The present research was conducted to assess the competition of four cover crop species including the Festuca ovina L., Festuca rubra L., Agropyron desertorum (Fischer ex Link) Shultes, and Bromus tomentellus Boiss with the weeds as well as enhancement of their establishment. B. tomentellus with 7.7 and 8.73 t h–1 had the highest dry weight production in 2016 and 2017, respectively. In 2016, the highest reduction in the dry weight of the weeds (73%) was observed for the F. ovina, at the rate of 600 g active ingredient per ha–1 of herbicide. In 2017, the highest reduction in the dry weight of the weeds (90%) was recorded at the rate of 600 g active ingredient per ha–1 of herbicide for the. Dry weight of the dominant weeds decreased by 70% approximately with the and at the rate of 600 g active ingredient per ha–1 of herbicide. Shannon Wiener index decreased in all the treatments following the increase in the herbicide concentrations in 2016 and 2017. The interaction of cover crop species and herbicide on the Margalef index was significant in all the treatments in 2016 except for A. desertorum, as well as A. desertorum and in 2017. Margalef index reduced following the increase in the herbicide concentration in all the treatments. Highlights - Bromus tomentellus Bioss and Festuca ovina L had the highest biomass production. - Bromus tomentellus (90%) and Festuca ovina (73%) treatments had the highest decrease in total weed dry weight compared to control. - The highest reduction in dry weight of total dominant weeds was influenced by B. tomentellus and Festuca ovina 73% and 83% at the rate of 600 g a.i. ha–1 of Bromocide M.A. EC respectively. - Margalof index reduced following the increase in herbicide concentration in all treatments. - Bromus tomentellus, Festuca ovina has the potential for reducing weeds in orchards and croplands.

Adaptation and Some Quality Parameters of Cool Season Turfgrass Species in Samsun Conditions

The aim of this study is to determine adaptation and quality parameters of some cool season turfgrass cultivars and species, In the scope of this study, leaf form, variation of leaf colour according to the seasons, tiller number, thinning ratio, weed ratio and general appearance of the species were determined. The experiment was established according to confounding design with four replications in Samsun Conditions at November, 2010. According to 1000 seed weight and characteristics of the plants seeding ratios were determined as pure and viable seed as follows; Lolium perenne 40 g m-2, Festuca rubra var. rubra and Festuca rubra var. commutata 30 g m-2, Festuca arundinacea 40 g m-2, Poa pratensis 20 g m-2, Festuca rubra trichophylla 30 g m-2, Agrostis stolonifera and Agrostis tenuis 5 g m-2, Festuca ovina 25 g m-2. According to the results obtained from this study it was determined that species/cultivars have some superiority to each other because of their different morphological and physiological characteristics. When we consider weed competition, Lolium perenne and Festuca arundinaceae cultivars have to be added to the mixture in order to decrease weed competition. There was colour variation distinctively depending on the seasons for all species. But, compare to the others, cultivars of Agrostis sp. and Poa pratensis cultivars have the potential to keep leaf colour in different seasons. Leaf form and appearance of Festuca rubra, Poa trivialis and Festuca ovina are better than the others. In order to keep good conditions of turfgrass areas, especially after cutting in summer period, Poa pratensis and Poa trivialis should added in mixtures to get benefit their higher regenerating power.

Building a Reference Transcriptome for the Hexaploid Hard Fescue Turfgrass (Festuca brevipila) Using a Combination of PacBio Isoseq and Illumina Sequencing

Background: Hard fescue (Festuca brevipila Tracey, 2n=6x=42) is a cool season turfgrass with a fine leaf texture that performs well under low-input management. Breeding and genetics studies of F. brevipila have been limited due to the complexity of its hexaploid genome. To advance our knowledge of F. brevipila genomics, we used PacBio isoform sequencing to develop a reference transcriptome for this species. Results: Here, we report the F. brevipila reference transcriptome generated from root, crown, leaf, and inflorescence tissues. We obtained 59,510 full-length transcripts, of which 38,556 were non-redundant full-length transcripts. The longest and shortest transcripts were 11,487 and 58 bp, respectively. Distribution of synonymous distances among paralogs within F. brevipila suggested highly similar subgenomes that are difficult to distinguish from sequencing errors. To evaluate the phylogenetic relationships among F. brevipila and close relatives, we sequenced three additional transcriptomes using closely related species on an Illumina platform. The results of our phylotranscriptomic analysis supported the close relationships among F. brevipila (6x), Festuca ovina (4x), Festuca ovina subsp. ovina (2x), and Festuca valesiaca (2x), with high levels of discordance among gene trees. Conclusions: Overall, the F. brevipila PacBio Isoseq reference transcriptome provided the foundation for transcriptome studies and allowed breeders a resource for gene discovery in this important turfgrass species.

Changes in the distribution and abundance of Carex ericetorum in Britain since the 1970s

British populations of Carex ericetorum Poll. (Rare Spring Sedge) were visited between 2008 and 2015 to assess size, habitats, associated vegetation, management, threats and changes in abundance since the 1970s. C. ericetorum was relocated at 40 of the 64 sites visited, mainly in northwest England (24 sites) and East Anglia (nine sites); most populations that couldn’t be relocated were in southern and eastern England. Population sizes were usually small (<100 individuals) and had remained relatively stable or had increased in size since the 1970s. In southern and eastern England, C. ericetorum was restricted to species-rich calcareous grassland overlying chalk or limestone dominated by Festuca ovina and Bromopsis erecta. In northwest England, it was confined to limestone grassland dominated by Sesleria caerulea. Ideal management for C. ericetorum comprised autumn and winter grazing to maintain a short sward (<6 cm), although it had persisted in the absence of grazing where the growth of dominants was restricted by exposure and/or soil infertility. The main threat to its survival is now a lack of grazing leading to increased competition with tall grasses, although agricultural intensification had caused losses in the lowlands. Nitrogen deposition is also likely to have compounded these threats on some sites. Its survival on many sites will require the maintenance or reinstatement of grazing.