Isoprene-degrading bacteria associated with the phyllosphere of Salix fragilis, a high isoprene-emitting willow of the Northern Hemisphere

Background Isoprene accounts for about half of total biogenic volatile organic compound emissions globally, and as a climate active gas it plays a significant and varied role in atmospheric chemistry. Terrestrial plants are the largest source of isoprene, with willow (Salix) making up one of the most active groups of isoprene producing trees. Bacteria act as a biological sink for isoprene and those bacteria associated with high isoprene-emitting trees may provide further insight into its biodegradation. Results A DNA-SIP experiment incubating willow (Salix fragilis) leaves with 13C-labelled isoprene revealed an abundance of Comamonadaceae, Methylobacterium, Mycobacterium and Polaromonas in the isoprene degrading community when analysed by 16S rRNA gene amplicon sequencing. Metagenomic analysis of 13C-enriched samples confirmed the abundance of Comamonadaceae, Acidovorax, Polaromonas, Variovorax and Ramlibacter. Mycobacterium and Methylobacterium were also identified after metagenomic analysis and a Mycobacterium metagenome-assembled genome (MAG) was recovered. This contained two complete isoprene degradation metabolic gene clusters, along with a propane monooxygenase gene cluster. Analysis of the abundance of the alpha subunit of the isoprene monooxygenase, isoA, in unenriched DNA samples revealed that isoprene degraders associated with willow leaves are abundant, making up nearly 0.2% of the natural bacterial community. Conclusions Analysis of the isoprene degrading community associated with willow leaves using DNA-SIP and focused metagenomics techniques enabled recovery of the genome of an active isoprene-degrading Mycobacterium species and provided valuable insight into bacteria involved in degradation of isoprene on the leaves of a key species of isoprene-emitting tree in the northern hemisphere.

EFFECTS OF ANTHROPOGENIC IMPACT ON SEXUAL DIFFERENTIATION OF CERTAIN SPECIES OF THE GENUS SALIX

Plant organisms actively respond to changes in the natural components of their environment. A sensitive indicator of the adaptation of the plant organism to the environment is the state of the reproductive system. The article discusses the results of a study of the sex composition of populations and the quality of pollen grains of two species of the genus Salix. The peculiarities of the sexual sphere Salix fragilis and Salix dasyclados revealed during the work show the feminizing effect on the sexual structure of the populations of these types of anthropogenic factors. During the increase of stress conditions the level of vitality and fertilizing ability of pollen grains decreases. The results of the study confirm the possibility of using these plants as bioindicators of the environment.

A lesson in urban mycology: Critically Endangered polypore Trametes suaveolens (Basidiomycota) re-discovered in Estonia

The conspicuous, mostly willow-inhabiting polypore Trametes suaveolens is a threatened species in Northern Europe. In Estonia it is listed as Critically Endangered, and has not been found since 1984. We report an apparently viable population discovered in Central Tallinn, inhabiting old Salix fragilis and S. alba trees and stumps along ca. 1.5 km of the Baltic seashore. The host trees are prone to removal due to city development and park care reasons. We discuss potential conservation measures for sustaining this unique population in the urban conditions. Pajutagel (Trametes suaveolens) Eestis taasleitud Peamiselt remmelgatel silmatorkavaid viljakehi moodustav pajutagel (Trametes suaveolens) on Põhja-Euroopas ohustatud liik. Eestis on selle liigi seisund hinnatud kriitiliseks ja viimane dokumenteeritud leid pärineb 1984. aastast. Siinses artiklis kirjeldatakse Tallinnast avastatud populatsiooni, mis asustab u. 1,5 km mereäärsel lõigul rabeda remmelga (Salix fragilis) ja hõberemmelga (S. alba) vanu elus puid ja kände. See asurkond oli 2018. aastal küll elujõuline, kuid tema elupaika ohustavad linna arendustegevus ja pargihooldus. Artiklis esitatakse soovitusi nii pajutagla säilitamiseks Tallinnas kui ka üldiselt puitulagundavate ohustatud seeneliikide kaitseks linnatingimustes.

Monitoring of introduction resources of the Kulunda arboretum and allocation of valuable gene pool for protective afforestation

На примере Кулундинского дендрария приведены материалы мониторинга интродукционных ресурсов деревьев и кустарников. Успех введения их в культуру защитного лесоразведения базируется на детальном изучении эколого-биологических особенностей, опыта интродукции в новых условиях. Из-за возросшей в последние годы антропогенной нагрузки используемый ассортимент древесных растений в защитных лесных насаждениях аридных территорий требует обновления. Постановка проблемы включает – выделение ценного генофонда для создания семенных баз и выращивания адаптированного посадочного материала. Показано, что в условиях Кулундинской степи интродуценты в защитном лесоразведении используются еще недостаточно широко, ассортимент древесных видов беден (Betula pendula Roth., Populus balsamifera L., Pinus sylvestris L., Larix sibirica Ledeb., Salix fragilis L.). Сопутствующие древесные растения представлены Acer negundo L., Malus pallasiana Juz., Ulmus pumila L. Другие древесные виды применяются в защитном лесоразведении в ограниченных масштабах. Цель исследований – оценка интродукционной устойчивости генофонда Кулундинского дендрария на основе мониторинга и комплексного изучения их биологических особенностей в условиях Кулундинской степи для защитного лесоразведения. Кулундинский дендрарий создан в 1977 году, он расположен на территории Западно-Сибирской агролесомелиоративной опытной станции (участок 49098 м2, кадастровый номер 22:23:010003:0014). Тип почв – каштановые, легкосуглинистые. Основные запасы гумуса сосредоточены в верхнем горизонте и с глубиной уменьшаются от 2,7 до 0,6%, Глубина залегания грунтовых вод 5-6 м. Выявлено, что видовой состав деревьев и кустарников Кулундинского дендрария включает 143 таксона из 52 родов и 25 семейств. К числу хозяйственно ценных родовых комплексов относятся представители семейства Rosaceae. Установлено, что представители семейства Rosaceae, как интродукционный ресурс для обогащения лесомелиоративных комплексов и формирования комфортных условий проживания населения, занимает одно из самых крупных по таксономическому составу древесных видов и важным по многофункциональному использованию. Рассмотрены методические подходы по проведению мониторинга интродукционных ресурсов, предложена методика расчета интродукционной устойчивости растений к новым условиям произрастания включающая группы признаков (зимостойкость, засухоустойчивость, побегообразовательная способность, прирост в высоту, генеративное развитие, возможный способ размножения в культуре) и приведено соотношение коллекционного фонда по показателям и размерностям шкал. Материалы по мониторингу интродукционных ресурсов Кулундинского дендрария ФНЦ агроэкологии РАН по оценке адаптированного генофонда для защитного лесоразведения будут использованы для разработки мероприятий по сохранению биоразнообразия и рациональному использованию хозяйственно ценных растений; с учетом полученных данных отобраны перспективные виды для обогащения защитных лесных насаждений Кулундинской степи. On the example of the Kulunda arboretum the materials of monitoring of introduction resources of trees and bushes are given. The success of their introduction into the culture of protective afforestation is based on a detailed study of ecological and biological features, the experience of introduction in new conditions. Due to the increased anthropogenic load in recent years, the range of woody plants used in the protective forest plantations of arid areas requires updating. The problem statement includes the allocation of a valuable gene pool for the creation of seed bases and the cultivation of adapted planting material. It is shown that in the conditions of the Kulunda steppe the introduced species in the protective afforestation are not widely used yet, the range of tree species is poor (Betula pendula Roth., Populus balsamifera L., Pinus sylvestris L., Larix sibirica Ledeb., Salix fragilis L.). Accompanying woody plants are presented by Acer negundo L., Malus pallasiana Juz., Ulmus pumila L. Other tree species are used in protective afforestation on a limited scale. The purpose of the evaluation introduction the sustainability of the gene pool of Salted arboretum on the basis of a comprehensive monitoring and study their biological features under conditions of Kulundinskaya steppe for protective afforestation. Kulundinsky arboretum was established in 1977, it is located on the territory of the West Siberian agroforestry experimental station (plot 49098 m2, cadastral number 22:23:010003:0014). Type of soil – chestnut, light-loamy. The main reserves of humus are concentrated in the upper horizon and with a depth decrease from 2.7 to 0.6%, the depth of groundwater 5-6 m. It was revealed that the species composition of trees and shrubs of the Kulundinsky arboretum includes 143 taxa from 52 genera and 25 families. Among the economically valuable generic complexes are representatives of the family Rosaceae. It is established that the representatives of the family Rosaceae, as an introduction resource for the enrichment of forest reclamation complexes and the formation of comfortable living conditions of the population, is one of the largest in taxonomic composition of wood species and important for multifunctional use. Methodical approaches to carrying out monitoring of introduction of resources, the proposed method of calculation introduction the resistance of plants to new conditions including the characteristics group (winter hardiness, drought tolerance, pobegoobrazovatelnost ability, growth in height, generative development, possible method of propagation in culture) and the ratio of collection Fund on indicators and the dimensions of the scales. Materials on monitoring of introduction resources of the Kulundinsky arboretum of the Federal CENTER of Agroecology of the Russian Academy of Sciences on assessment of the adapted gene pool for protective afforestation will be used to develop measures for biodiversity conservation and rational use of economically valuable plants; based on the data obtained, promising species for the enrichment of protective forest plantations of the kulundin steppe were selected.

THE DEPENDENCE OF MORPHOLOGICAL AND PHYSIOLOGICAL INDICATORS OF THE LEAVES OF WOODY PLANTS ON THE DEGREE OF TECHNOGENIC POLLUTION

Plants of modern urban ecosystem suffer from negative effects of a series of technogenic pollution which leads to changes in their morphological and physiological state. The reason for this is the penetration of phytotoxicants into plant organs, primarily, into leaves, thus distorting the structural components of cells and their functioning. In various species the degree of this reaction is manifested differently, so this fact must be taken into consideration when creating environmentally effective plantations. For this purpose the integrated study of the impact of pollutants on the morpho-physiological state of deciduous trees was conducted. Some morphological, physiological and biochemical indicators of leaves of Tilia cordata Mill., Populus tremula L., Salix fragilis L., Salix alba L. from different urban areas, characterized by different levels of technogenic pollution, were also studied. It was found out that the increase of technogenic load led to the decrease in the size of leaves, the increase of their necrotization and the total ash content of the tissues of these organs as well as the reduction of the photosynthetic pigments concentration with increase of relative portion of carotenoids which is the most significantly revealed in the leaves of the lime-tree, brittle willow and, to a lesser extent, in the white willow. At the same time the increased relative portion of carotenoids in the photosynthetic organs in case of strong pollution by pollutants indicates an increase of the protective role of the yellow pigment. Besides, the increased ratio of chlorophyll a/b characteristic for the resistant plant species was established in the leaves of these trees, which is a sign of a higher potential photochemical activity of leaves and the rate of photosynthesis. All the studied morpho-physiological indicators characterize a greater resistance to pollutants of Tilia cordata, Salix fragilis, Salix alba, which can be recommended for the reconstruction of the sanitary and protective plantations of Arzamas. The studied tree species have a great capacity of gettering harmful technogenic substances with a further effective ability to accumulate them in the tissues of the leaves.

Productivity and health of brittle willow forest stands in the floodplains of medium and small rivers in the Central Chernozem region

The article is devoted to the study of conformities to law of accumulation of barrel wood stock and change of the age sanitary state of brittle willow (Salix fragilis L.) stands, growing on the banks of the middle and small rivers. Research was conducted on the example of the test areas, set in August, 2010, in flood bottom of Shchigor River, Shchigor district, Kursk region. It is educed, that the largest stands of brittle willow are in wet habitat with flow ground waters in flood bottom.