Extramatrical Mycelium and Ectomycorrhizal Community Composition of Quercus pubescens in a Sub-Mediterranean Stress-Prone Environment

Temporal studies that would offer insight into resilience of ectomycorrhizal (ECM) communities in stress prone climates are scarce despite their role in tree nutrition and water supply. Our study characterized the vitality, community composition, diversity, and function of Quercus pubescens Willd. ECM fungi in the Sub-Mediterranean stress-prone environment for 2 consecutive years (June 2016–May 2018) and related the investigated measures to environmental parameters. ECM community was assessed for species actively associating with root tips and exploring the soil volume through the assessment of mycelial ingrowth into sand-filled mesh bags. The investigated period was characterized by a drier than average summer combined with wildfire in 2016 followed by another dry summer in 2017. The vital to non-vital ECM root tip ratio decreased below one in August 2016 and remained low until January 2018. This was ascribed to a series of stress events that occurred at the site including sequential droughts and wildfire. The most abundant ECM lineages on root tips were Tomentella and other Thelephoraceae, Sebacina, and Cenococcum while in mesh bags the most abundant were Tomentella, Sebacina, Pseudotomentella, Pyronemataceae, Inocybe, Cortinarius, Agaricales, and Boletales lineages. High intra-site variability was observed, with ECM communities directly associated with root tips and exploring the soil volume varying significantly among the plots. Community composition was stable over time, while species richness varied with mean air and soil temperature, relative air humidity, and solar radiation. The most abundant exploration type observed at this site was short distance, which was associated with precipitation along with long distance exploration type. The medium distance exploration type was temporally variable and responded to soil temperature and relative air humidity reflecting seasonality at the site. The presented results indicate complex relationships between environmental parameters, abiotic stress, and ECM fungi.

Characteristics of Pinus sibirica Du Tour mycotrophy in cedar stands of Tomsk region

В припоселковых кедровниках южной тайги Томской области исследовали образцы эктомикориз Pinus sibirica, собранные с корней подроста или из почвенных образцов. Для DEEMY-анализа отбирали живые, функционирующие эктомикоризы. Срезы эктомикориз делали на замораживающем микротоме МЗ-2, изучая их параметры с помощью микроскопа Axiostar plus, видеокамеры Watec LCL 217 и программного обеспечения SIAMS MesoPlant. Возраст сеянцев определяли при помощи прибора LinTab-6 Tree-ring Station . Выделение ДНК, ПЦР проводили по протоколам наборов Quiagen. Результаты обрабатывали по алгоритму анализа ANOVA и многофакторной модели дисперсионного анализа (Statistica 10). Выявлено, что параметры ширина мезодермы , радиус центрального проводящего цилиндра и ширина грибной мантии коррелируют друг с другом. В возрастной группе 1 корреляции сохранялись, в возрастной группе 2 связь между параметрами отсутствовала. У подроста кедра при увеличении размеров корня достоверно увеличивалась и толщина грибной мантии. Анализ сиквенсов ITS регионов рибосомальных генов ДНК показал, что туберкулизированные эктомикоризы образованы Suillus sibiricus, простые эктомикоризы, покрытые белыми гидрофобными гифами, формирует Cortinarius sp., ветвящиеся эктомикоризы с желтыми гидрофобными ризоморфами Piloderma olivaceum. Результаты выявили высокую частоту встречаемости контактных эктомикориз в фитоценозе с максимальной густотой стояния деревьев в кедраче пос. Зоркальцево. В Лоскутовском кедровнике и в Тимирязево, с наибольшим распространением стратегии со средней дистанцией действия (Medium distance exploration type), индекс сомкнутости крон составляет 0,40,6. Оптимальное состояние Лоскутовского кедровника, вероятно, объясняет обнаруженное здесь большое разнообразие и видов эктомикоризообразующих макромицетов, и всех трех exploration типов: и Contact, и Medium, и Short. Samples of Pinus sibirica ectomycorrhizal tips form seedlings roots and soil samples were examined in cedar forests of Tomsk region southern taiga. Alive and functioning ectomycorrhizas were selected for DEEMY-analysis. Ectomycorrhizal tips cross sections were performed with an MZ-2 freezing microtome, their parameters were studied with an Axiostar plus microscope, a Watec LCL 217 video camera and SIAMS MesoPlant software. Seedlings age was determined with a LinTab-6 Tree-ring Station . DNA isolation, PCR were performed according to Quiagen kit protocols. The results were processed with one-way ANOVA test (Statistica 10). It is shown that width of cortex , stele radius and mantle width parameters correlate with each other. The width of fungal mantle increased with the increasing root sizes. The correlations remained in the Age group 1, there were found no correlations between the parameters in the Age group 2. The analysis of DNA ribosomal genes ITS regions sequences showed that tuberculate ectomycorrhizas were formed by Suillus sibiricus, unramified ectomycorrhizas with white hydrophobic rhizomorphs were formed by Cortinarius sp., ramified ectomycorrhiza with yellow hydrophobic rhizomorphs were formed by Piloderma olivaceum. High occurrence of Contact exploration type ectomycorrhizas was registered in Zorkaltsevo biotop with thehighest degree of tree density. Medium distance exploration type was common in Loskutovo and Timiryazevo where the degree of tree density was 0.40.6. The optimal state of Loskutovo biotope probably explains the high diversity of ectomycorrhizal macromycetes species and the exploration types (Contact, Medium, and Short) balance registered in the site.