Some plant species are able to distinguish between neighbours of different genetic identity and attempt to pre‐empt resources through root proliferation in the presence of unrelated competitors, but ...avoid competition with kin. However, studies on neighbour recognition have met with some scepticism because the mechanisms by which plants identify their neighbours have remained unclear. In order to test whether root exudates could mediate neighbour recognition in plants, we performed a glasshouse experiment in which plants of Deschampsia caespitosa were subjected to root exudates collected from potential neighbours of different genetic identities, including siblings and individuals belonging to the same or a different population or species. Our results show that root exudates can carry specific information about the genetic relatedness, population origin and species identity of neighbours, and trigger different responses at the whole root system level and at the level of individual roots in direct contact with locally applied exudates. Increased root density was mainly achieved through changes in morphology rather than biomass allocation, suggesting that plants are able to limit the energetic cost of selfish behaviour. This study reveals a new level of complexity in the ability of plants to interpret and react to their surroundings.
The epithet “
alpina
” has been recurrently used in the genus
Deschampsia
to name plants located in northern regions of Europe, Asia and North America, as a species (
Deschampsia alpina
(L.) Roem. & ...Schult.), but also in infraspecific categories (Deschampsia cespitosa subsp. alpina Tzvel. and Deschampsia cespitosa var. alpina Schur.). The morphological and molecular available evidence suggests the existence of a single species,
Deschampsia cespitosa
(L.) P. Beauv., in which individuals belonging to the same morphological gradient have received different names in different taxonomic categories throughout its wide distribution range. An evaluation of the available names indicates that all uses of the epithet “
alpina
” are illegitimate. A new combination is proposed at the infraspecific level as Deschampsia cespitosa subsp. neoalpina Chiapella, Xue & Greimler.
Prairies in the Pacific Northwest are dominated by perennial bunchgrasses. A Mycena in the citrinomarginata complex was observed to tightly co-occur with bunchgrasses at several prairie study sites. ...Mapping and spatial statistics showed that it was strongly and significantly associated with Festuca roemeri tussocks. We further found that this fungus is attached to F. roemeri roots (17/17 examined) and both specific primers and next-generation DNA sequencing established that the fungus is in the roots, suggesting that M. citrinomarginata may be endophytic or biotrophic in some contexts, and not simply saprotrophic. These results combined with a literature review indicate that Mycena species are often found as endophytes in grass roots. Given the importance of grasses and grasslands for humans, this ecological association deserves further study.
Decomposition is a critical source of plant nutrients, and drives the largest flux of terrestrial C to the atmosphere. Decomposing soil organic matter typically contains litter from multiple plant ...species, yet we lack a mechanistic understanding of how species diversity influences decomposition processes. Here, we show that soil C and N cycling during decomposition are controlled by the composition and diversity of chemical compounds within plant litter mixtures, rather than by simple metrics of plant species diversity. We amended native soils with litter mixtures containing up to 4 alpine plant species, and we used 9 litter chemical traits to evaluate the chemical composition (i.e., the identity and quantity of compounds) and chemical diversity of the litter mixtures. The chemical composition of the litter mixtures was the strongest predictor of soil respiration, net N mineralization, and microbial biomass N. Soil respiration and net N mineralization rates were also significantly correlated with the chemical diversity of the litter mixtures. In contrast, soil C and N cycling rates were poorly correlated with plant species richness, and there was no relationship between species richness and the chemical diversity of the litter mixtures. These results indicate that the composition and diversity of chemical compounds in litter are potentially important functional traits affecting decomposition, and simple metrics like plant species richness may fail to capture variation in these traits. Litter chemical traits therefore provide a mechanistic link between organisms, species diversity, and key components of below-ground ecosystem function.
•Oak seedlings with high N internal pool better grow without soil water limitation.•Intraspecific competition is higher than interspecific under high grass density.•N-loaded oaks should be planted to ...enhance regeneration under moderate stress.
In contrast to N soil availability or carbon (C) reserves, the role of N reserves in plant interactions has been under-researched. The N-loading of tree seedlings in nurseries before plantation within a forest community to increase their survival and early growth is still controversial. We hypothesized that a larger N-loaded pool in oak seedlings during year n − 1 might favor growth and function during year n through higher N remobilization, and thus lessen the impact of competition from Deschampsia cespitosa (tussock grass).
In 2015, we cultivated two sets of one-year oak seedlings in 20 L pots with two nitrogen supply levels: no supply (N-unloaded) and 87 kg ha−1 (N-loaded), without competition and without water limitation. A greenhouse experiment was then undertaken in 2016 with the same two oak batches, but with 0, 1, 2 or 3 tillers of D. cespitosa in both N-loaded and N-unloaded batches. Half the pots were subjected to drought for one month (August 2016).
Soil water availability was the prime factor driving plant growth and photosynthetic responses in oak, both with and without competition. Under well-watered conditions, a greater internal N pool was correlated with higher oak photosynthesis. A high internal N pool was also beneficial to oak seedlings under low competitive pressure from D. cespitosa. However, when grass density increased, intraspecific competition outweighed interspecific competition, and attenuated the negative effect of D. cespitosa on oak seedlings.
A carry-over effect of N-loading thus had a positive effect on growth and function in oak seedlings when no water stress occurred under low competition by D. cespitosa: this effect may derive from more N storage in perennial tissues, resulting in more N mobilized during vegetative growth. Our results underline the importance of the internal N pool in plant competition, and are evidence that a higher potential regenerative success rate of oak seedlings is related to abiotic conditions, competitive pressure and internal N pool.
The grass
Deschampsia cespitosa
is a variable taxon out of which many varieties, subspecies and endemic species have been separated. In this paper, the variation in genome size (GS) and ploidy of ...this grass including several of its subspecies and two related species in Eurasia was investigated by flow cytometric (FCM) measurements. GS and ploidy data were also related to specific environments and reproduction mode. Ploidy levels found by FCM were confirmed by chromosome counts of diploid (2
n
= 26) and tetraploid (2
n
= 52) samples. Seminiferous (seed bearing)
D. cespitosa
was mainly diploid (GS between 3.754 and 5.438 pg/1C). GS variation in diploids showed a geographic pattern with a significant difference (
H
= 41,441,
P
< 0.001) between European (median = 4.377 pg) and Asian (median = 4.881 pg) accessions. Genome size (1C) in tetraploids ranged from 7.9426 to 9.0399 pg. Tetraploid seminiferous
D. cespitosa
was found mostly in disturbed habitats in western and southern Europe, while tetraploids in Asia were registered in wet Arctic habitats. Genome size (1C between 8.3278 and 8.8603 pg) of the pseudoviviparous plants (spikelets produce plantlets asexually) of wet habitats in central and northern Europe indicated tetraploidy. A putative triploid (GS 6.6817 pg) was detected in Iceland. Summing up, we found a high variation in GS on the geographic scale with significant regional differences in diploid
D. cespitosa
. Among the tetraploids, the asexually reproducing plants were bound to specific habitats, while the seminiferous plants showed a habitat preference similar to the diploids.
Nitrogen (N) deposition rates are increasing globally due to anthropogenic activities. Plant community responses to N are often attributed to altered competitive interactions between plants, but may ...also be a result of microbial responses to N, particularly root‐associated fungi (RAF), which are known to affect plant fitness. In response to N, Deschampsia cespitosa, a codominant plant in the alpine tundra at Niwot Ridge (CO), increases in abundance, while Geum rossii, its principal competitor, declines. Importantly, G. rossii declines with N even in the absence of its competitor. We examined whether contrasting host responses to N are associated with altered plant–fungal symbioses, and whether the effects of N are distinct from effects of altered plant competition on RAF, using 454 pyrosequencing. Host RAF communities were distinct (only 9.4% of OTUs overlapped). N increased RAF diversity in G. rossii, but decreased it in D. cespitosa. D. cespitosa RAF communities were more responsive to N than G. rossii RAF communities, perhaps indicating a flexible microbial community aids host adaptation to nutrient enrichment. Effects of removing D. cespitosa were distinct from effects of N on G. rossii RAF, and D. cespitosa presence reversed RAF diversity response to N. The most dominant G. rossii RAF order, Helotiales, was the most affected by N, declining from 83% to 60% of sequences, perhaps indicating a loss of mutualists under N enrichment. These results highlight the potential importance of belowground microbial dynamics in plant responses to N deposition.
To investigate the effects of plant growth regulators on photosynthesis and grass yield of tussock grass (
Deschampsia cespitosa
), a random block experiment was conducted, testing the effects of ...different chemicals on the photosynthesis and growth of the grass during heading stage. The treatments were: triacontanol (0.15, 0.30, 0.45 and 0.60 mg/L), auxin (20, 30, 40 and 50 mg/L), trinexapac-ethyl (141, 282, 423 and 564 g/hm
2
) and paclobutrazol (50, 100, 200 and 400 g/hm
2
). The results indicate that treatment with each of the four plant growth regulators increased the yield of
D. cespitosa
; however, treatment with 30 mg/L auxin had the best effect on improving the yield of fresh and dry hay, with an increase of 21.62 and 39.01%, respectively, compared to CK. Compared with CK, spraying with triacontanol had no significant effect on chlorophyll content and leaf area of
D. cespitosa
(
P
> 0.05), although spraying with 0.15 mg/L triacontanol resulted in a significant increase of net photosynthetic rate (26.68%), stomatal conductance (23.07%) and transpiration rate (11.11%) compared to CK (
P
< 0.05). After spraying 50.0 mg/L auxin, the chlorophyll content and leaf area of the leaves increased by 42.39 and 50.91% respectively compared to CK, and spraying 30 mg/L auxin resulted in a significant increase in the net photosynthetic rate (58.71%), stomatal conductance (47.37%) and transpiration rate (44.83%), which increased by and compared to CK (
P
< 0.05). Spraying 423.0 g/hm
2
of trinexapac-ethyl had a significant impact on the chlorophyll content and leaf area of
D. cespitosa
leaves (
P
< 0.05), which increased by 53.63 and 34.15% respectively compared to CK. The concentration of trinexapac-ethyl had a significant impact on the net photosynthetic rate, stomatal conductance, intercellular CO
2
concentration, and transpiration rate of the leaves (
P
< 0.05), with an increase of 40.3, 50.0, 18.62 and 42.86%, respectively, compared to CK. Spraying 400 g/hm
2
paclobutrazol had a significant impact on the chlorophyll content and leaf area (
P
< 0.05), which were 51.69 and 38.36% higher than the corresponding values in the CK group. Spraying 50.0 g/hm
2
paclobutrazol significantly increased the net photosynthetic rate (54.5%), stomatal conductance (41.18%) and transpiration rate (45.76%) of the leaves of treated plants compared with the control (
P
< 0.05). In summary, spraying 30.0 mg/L of auxin during the heading stage of the
D. cespitosa
can significantly increase the net photosynthetic rate, stomatal conductance, and transpiration rate of the leaves. The auxin treatment produced the best results in terms of yield of
D. cespitosa
hay.
The terrestrial high-Arctic has, so far, escaped the worst impacts of non-native plant establishment. However, increasing human activity and changing climate raise the risk of introductions and ...establishment, respectively. The lack of biosecurity in the terrestrial Arctic is thus of concern. To facilitate the development of biosecurity measures on the rapidly warming and highly trafficked archipelago of Svalbard, we generated ecological niche models to map the bioclimatic niche potential of 27 non-native established or door-knocker vascular plant species across Svalbard, identify species with a high risk of widespread occupancy, and locate hotspots of potential current and future invasions. Under the current climate the three species with the highest threat in terms of broad potential area of occupancy and known invasion potential were Deschampsia cespitosa , Ranunculus subborealis subsp. villosus and Saussurea alpina . However, under future climate, most of the considered species have potentially wide distributions across the archipelago. Remote eastern islands were a hotspot region for broader potential establishment of non-native species under the current climate. Our results suggest that many non-native plant species have a broader macroclimatic niche on Svalbard than they currently occupy, and that other factors probably limit both dispersal and establishment outside their current localised distributions. Environmental management on Svalbard has a limited window of opportunity to act early in containing and preventing the spread of non-native plant species beyond the few settlements where they currently exist. Moreover, preventing introductions and establishments on the remote and rarely visited islands of Edgeøya, Barentsøya and Bjørnøya could be also a priority action to safeguard sanctuaries of the archipelago’s natural ecosystems.
Plastid genome analysis of non-model organisms provides valuable information for basic research e.g., molecular evolutionary genomics, phylogeny and phylogeography.
is the most widespread species of ...the genus and it is a common grass that is found across Eurasia and North America. Scattered populations in regions of appropriate ecological conditions are also found in Australia, New Zealand and southern South America, where it is sympatric with
. We analyzed the plastid genome of a sample of
of the Austrian Alps using high-throughput sequencing. The plastid (cp) genome shows the typical quadripartite structure with a length of 135,340 bp, comprising a large single-copy (LSC) region of 79,992 bp, a small single-copy (SSC) region of 12,572 bp and two inverted repeats (IR) regions of 21,388 bp each. It contains 115 genes, including 85 protein-coding genes, four ribosomal RNA genes and 30 transfer RNA genes. The GC content (%), number of repeats and microsatellites, RNA editing sites and codon usage were highly similar to those of
. The results of this present study highlight the extremely conserved nature of the cp genome in this group, since the comparison involved individuals separated by about 13,000 km, from the Alps to Antarctica.
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