1,721,236 research outputs found
Response of beech and oak forests to global change related stresses in Alps and Appennines
No full textForest canopy reduction stimulates xylem production and lowers carbon concentration in fine roots of European beech
No full textForest canopy reduction is well known to affect the coarse and fine root biomass production. Seasonality,
to the same extent, is acknowledged to vary the non-structural carbon content. However, the fine root
response in terms of carbon concentration to both canopy cover and seasonal change remains unclear.
To this aim, morphological and anatomical traits like xylem percentage, carbon concentration and
starch content were measured in mid-summer and early-fall on fine roots of three beech stands differing
in canopy cover and basal area.
The results highlighted a significant effect of canopy cover on the xylem area percentage throughout
the <2 mm diameter fine root population, as the lower the canopy cover is, the larger the xylem area
is. Moreover, an inverse relationship occurred between carbon concentration and xylem area percentage,
highlighting the key role played by this anatomical trait. In order of magnitude, the significant carbon
concentration decrease observed 5 years after felling was 15 kg ha1 for a mean fine root biomass of
200 g m2. For a given xylem percentage, starch concentration seasonal change partially explained the
carbon concentration decrease with the incipient dormancy. Root tissue density significantly decreased
with soil depth in mature and 15-yr-old conversion stands, whereas it did not in recently cut (5-yrold)
conversion stand.
Outcomes are that canopy closure in the mature stand, which increases the fine root standing crop, produced
a higher total carbon input into the soil. Moreover, fifteen years since felling appeared sufficient for
detecting a clear trend in the recovery of fine root biomass to pre-thinning levels
Adaptation and restoration of Mediterranean forests: the role of the hidden half
No full textAlthough the root system represents approximately half of the plant biomass, due mainly to difficulties in methodology, it is still poorly investigated and understood. However,
Flora Mediterranea 27 — 2017 29
the root system provides essential functions to the plant such as anchorage and water and
nutrient uptake. Moreover, in order to cope with environmental constrains, plant roots
show high plasticity, which can give important information on specific plant adaptation
mechanisms. For example, coarse roots displacement shows a clear asymmetry when plant
grows on slope conditions. Thus, root plasticity knowledge may implement plant reforestation and/or afforestation activities, such as seedlings establishment, on steep slopes or in
those areas where a prevailing wind occurs. Fine roots, which respond to a strict cost-benefit analysis, are fast produced and discarded in a complex seasonal dynamics and modify
their development depending on the soil water availability. In this case, in areas characterized by a seasonal drought period, studying fine root compartment may indicate the best
species or genotype for an assisted migration approach. Finally, as all models predict a
worsening of climate change effects on Mediterranean vegetation, independently from the
type of forest restoration strategy that will be adopted, studies regarding how roots will
cope and respond to these stressors become of primary importance
The role of the “Giardino della Flora Appenninica di Capracotta” (Molise-Italy) in the biodiversity conservation
No full text
Advances in understanding root development in forest trees
No full textIn forest ecosystems, root systems represent up to 40% of the biomass, and around 75% of the annual net primary production is allocated to the fine root component (roots with a diameter of less than 2 mm). Fine roots are involved in nutrition, whereas coarse roots (more than 2 mm in diameter) contribute to tree anchorage and stability. Root studies are necessary to understand whether the natural level of root plasticity is able to respond to the foreseen worsening global environmental scenario. In this chapter, the author principally focuses on root turnover and root system architecture parameters describing respectively the plasticity of fine and coarse roots. An example is provided on how the methods used can enable the analysis of tree responses to abiotic stressors such as drought and fire as well as mechanical forces. The concluding remarks highlight the importance of including root research when planning landscape forest restoration of specific sites
MicroRNAs expression patterns in the response of poplar woody root to bending stress
No full textMain conclusion: The paper reports for the first time, in poplar woody root, the expression of five mechanically-responsive miRNAs. The observed highly complex expression pattern of these miRNAs in the bent root suggest that their expression is not only regulated by tension and compression forces highlighting their role in several important processes, i.e., lateral root formation, lignin deposition, and response to bending stress. Mechanical stress is one of the major abiotic stresses significantly affecting plant stability, growth, survival, and reproduction. Plants have developed complex machineries to detect mechanical perturbations and to improve their anchorage. MicroRNAs (miRNAs), small non-coding RNAs (18–24 nucleotides long), have been shown to regulate various stress-responsive genes, proteins and transcription factors, and play a crucial role in counteracting adverse conditions. Several mechanical stress-responsive miRNAs have been identified in the stem of Populus trichocarpa plants subjected to bending stress. However, despite the pivotal role of woody roots in plant anchorage, molecular mechanisms regulating poplar woody root responses to mechanical stress have still been little investigated. In the present paper, we investigate the spatial and temporal expression pattern of five mechanically-responsive miRNAs in three regions of bent poplar woody taproot and unstressed controls by quantitative RT-PCR analysis. Alignment of the cloned and sequenced amplified fragments confirmed that their nucleotide sequences are homologous to the mechanically-responsive miRNAs identified in bent poplar stem. Computational analysis identified putative target genes for each miRNA in the poplar genome. Additional miRNA target sites were found in several mechanical stress-related factors previously identified in poplar root and a subset of these was further analyzed for expression at the mRNA or protein level. Integrating the results of miRNAs expression patterns and target gene functions with our previous morphological and proteomic data, we concluded that the five miRNAs play crucial regulatory roles in reaction woody formation and lateral root development in mechanically-stressed poplar taproot
Rhizosphere bacteria affect plant performance and Cd accumulation of poplar (clone ‘I-214’)
No full text"The effects of moderate cadmium soil concentrations on selected physiological parameters of clone ‘I-214’, Populus deltoides × Populus nigra (P. × euramericana (Dode) Guinier), inoculated at root level with Pseudomanos fluorescens and Micosat F Fito were investigated. A pot experiment was held in a screened greenhouse, where plants were subjected to 40 ppm of Cd, against a control treatment. In order to evaluate the effects of plant–microbe interactions, plant growth and physiology and microbial activity were monitored throughout the experiment. Whereas, at the end of the cultivation period, plant tissues were analyzed for Cd content. The Cd amount in tissues exhibited improved Cd absorption in inoculated plants. Heavy metal concentration was high in roots of plants inoculated with P. fluorescens, and in leaves, suggesting a role of microbes in improving metal uptake. The poplar clone ‘I-214’ responded to Cd contamination and microbial inoculation modulating plant growth, gas exchange, and the photosynthetic apparatus; therefore, moderate soil Cd concentration did not inhibit stomatal opening and did not affect negatively photosynthetic functions. Plant-microbe symbiosis increased total removal of Cd, without interfering on plant growth, while improving somewhat physiological behavior. After Cd treatment, microscope observations showed a complete microbial colonization of roots. The Cd concentrations in plant tissues suggested two mechanisms of soil decontamination by microbes: improved Cd accumulation in roots of inoculated plants with phytostabilization and high translocation of Cd to leaves. A detailed proteomic approach combined with multivariate statistical analysis is in progress for deeper insights into the complex cellular processes involved in plant Cd accumulation and to identify key factors regulating Cd phytostabilization and translocation.
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