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Journal of Biogeography Dec 2022Leaves support a large diversity of fungi, which are known to cause plant diseases, induce plant defences or influence leaf senescence and decomposition. To advance our...
AIM
Leaves support a large diversity of fungi, which are known to cause plant diseases, induce plant defences or influence leaf senescence and decomposition. To advance our understanding of how foliar fungal communities are structured and assembled, we assessed to what extent leaf flush and latitude can explain the within- and among-tree variation in foliar fungal communities.
LOCATION
A latitudinal gradient spanning . 20 degrees in latitude in Europe.
TAXA
The foliar fungal community associated with a foundation tree species, the pedunculate oak .
METHODS
We examined the main and interactive effects of leaf flush and latitude on the foliar fungal community by sampling 20 populations of the pedunculate oak across the tree's range. We used the ITS region as a target for characterization of fungal communities using DNA metabarcoding.
RESULTS
Species composition, but not species richness, differed between leaf flushes. Across the latitudinal gradient, species richness was highest in the central part of the oak's distributional range, and foliar fungal community composition shifted along the latitudinal gradient. Among fungal guilds, the relative abundance of plant pathogens and mycoparasites was lower on the first leaf flush, and the relative abundance of plant pathogens and saprotrophs decreased with latitude.
CONCLUSIONS
Changes in community composition between leaf flushes and along the latitudinal gradient were mostly a result of species turnover. Overall, our findings demonstrate that leaf flush and latitude explain 5%-22% of the small- and large-scale spatial variation in the foliar fungal community on a foundation tree within the temperate region. Using space-for-time substitution, we expect that foliar fungal community structure will change with climate warming, with an increase in the abundance of plant pathogens and mycoparasites at higher latitudes, with major consequences for plant health, species interactions and ecosystem dynamics.
PubMed: 36636040
DOI: 10.1111/jbi.14508 -
Phytopathology Aug 2004ABSTRACT Phytophthora cinnamomi is the causal agent of a perennial canker that develops on the lower bole on northern red oak and pedunculate oak. The disease has a...
ABSTRACT Phytophthora cinnamomi is the causal agent of a perennial canker that develops on the lower bole on northern red oak and pedunculate oak. The disease has a limited range in Europe, being reported only in southwest France. This limited distribution is probably linked to the susceptibility of P. cinnamomi to frost. A model was developed in previous work to estimate the impact of temperatures of <0 degrees C on the winter survival of P. cinnamomi in trunk cortical tissues and on the subsequent development of cankers. In this article, we report the use of this model to simulate canker development in 503 locations across France during a 30-year period. The predicted canker extension decreased sharply when the median P. cinnamomi winter survival index decreased from 0.95 to 0.65, with cankers that poorly developed when the median survival index was lower than 0.5 to 0.6. The actual incidence of the disease in 192 stands located across southwest France was compared with that of the model outputs. Both presence of disease in stands and frequency of cankered trees in infected stands, but not canker size on infected trees, were strongly related to the median P. cinnamomi survival index. No disease was present in stands with median survival index lower than 0.65, and the frequency of cankered trees in infected stands remained very low in stands with a median survival index between 0.65 and 0.70. Aspect was an additional factor explaining disease incidence, while the effect of elevation was likely due to its effect on winter temperatures. Maps of winter suitability to P. cinnamomi-induced cankers on oaks in France are presented.
PubMed: 18943102
DOI: 10.1094/PHYTO.2004.94.8.826 -
Plant Disease Nov 2023Tea (Camellia sinensis (L.) Kuntze) is among the most significant industrial crops due to its distinctive fragrance and flavor generated (Bag et al. 2022). From October...
Tea (Camellia sinensis (L.) Kuntze) is among the most significant industrial crops due to its distinctive fragrance and flavor generated (Bag et al. 2022). From October to December in 2021, a leaf spot disease affected the quality and yield of tea (C. sinensis var. assamica cv. Yunkang 10), in Pu'er (100.57°E, 22.45°N), Yunnan province, China. Based on the survey, the incidence was approximately 15% in a plantation of 4500 m2 (2050 tea trees approximately). The symptoms on leaves were regular circular, dark brown lesions with black conidiomata in gray centers. Twenty symptomatic leaves were collected from 10 trees. After rinsing and surface sterilization (75% ethanol for 30 s and 3% NaClO for 90 s, rinsed 3 times with sterile distilled water), diseased tissues (5 × 5 mm) were cut at the junction of infected and healthy site and placed on potato dextrose agar (PDA) (3 pieces per plate) and incubated in the dark at 28℃ for 5 days (Mao et al. 2023). Three single-spore isolates 6a-H-1, 6a-H-2 and 6a-H-3 were obtained, which showed identical in morphology and molecular analysis. Therefore, the targeted isolate 6a-H-2 was used for further study. Fungal colonies were white, then gradually turning into goose yellow (Fig.2. A-C). Chlamydospores were dark brown and oval (Fig.2. G). Asci produced after 30 days approximately, were orange-red, nearly spherical, rough-surface, and measured as 470 µm ± 11.68 µm (n = 50) (Fig.2. H). Ascospores were released from the asci orifice (Fig.2. I) which were hyaline, fusoid with rounded ends, straight to slightly curved, two septate, slightly constricted at the septum, and ranged from 48.77 ± 2.76 µm × 6.22 ± 0.41 µm (n = 50) (Fig.2. D-F). Macroconidia were cylindrical (Fig.2. J), rounded at both ends, straight, with an average length of 63.5 ± 0.31 μm × 2.62 ± 0.03 μm without septa (n=50) (Fig.2. M-O). Stipe extension terminated in sphaero-pedunculate vesicles (Fig.2. K-L). The morphological features were consistent with the descriptions of Calonectria ilicicola (Pei et al. 2015; Polizzi et al. 2012). The pathogen was confirmed to be C. ilicicola by amplification and sequencing of the histone (HIS3), translation elongation factor 1-alpha (TEF1) and calmodulin (CAL) genes using primers H3-3F/H3-3R, EF1-728F/EF1-986R and CAL-228F/CAL-2Rd, respectively (Crous et al. 2004). The sequences of PCR products were deposited in GenBank with accession numbers OR188222 (HIS3), OR188223 (TEF1) and OR188221 (CAL). BLAST searches of the obtained sequences revealed 99.22% (510/514 nucleotides), 98.37% (241/245 nucleotides) and 99.58% (472/474 nucleotides) homology with those of C. ilicicola (CBS 190.50) in GenBank (AY725676, AY725726 and AY725764), respectively. Phylogenetic analysis (MEGA 7.0) using the Maximum Likelihood method placed the isolate 6a-H-2 in a well-supported cluster with C. ilicicola. The pathogenicity of 6a-H-2 was tested through a pot assay. Five healthy plants had their leaves scratched with a sterilized needle, then inoculated by spraying 20 mL of spore suspension (105 spores mL-1) of 6a-H-2. Five additional tea plants sprayed with sterile distilled water served as controls. All plants were placed in a growth chamber at 28℃, with 70% relative humidity. The symptoms developed on all inoculated leaves but not on the control leaves. The lesions were first visible 72 h after inoculation, and typical lesions similar to those observed on field plants appeared after 10 days. The same fungus was reisolated and identified based on the morphology and molecular analyses (HIS3, TEF1 and CAL) from the infected leaves but not from the non-inoculated leaves. To our knowledge, this is the first report of leaf spot on tea caused by C. ilicicola in China. This study provides valuable information for the identification and control of the leaf spot on tea.
PubMed: 38037201
DOI: 10.1094/PDIS-09-23-1745-PDN -
Frontiers in Plant Science 2023Beneficial effects of silicon (Si) on plants have primarily been studied in crop species under single stress. Moreover, nutrient acquisition-based responses to...
Beneficial effects of silicon (Si) on plants have primarily been studied in crop species under single stress. Moreover, nutrient acquisition-based responses to combination of biotic and abiotic stresses (a common situation in natural habitats) have rarely been reported, in particular in conjunction with soil amendments with Si. Pedunculate oak ( L.), one of the ecologically and economically most important tree species in Europe, is facing a severe decline due to combined stresses, but also problems in assisted regeneration in nurseries. Here, we studied the effect of Si supply on the leaf nutriome, root traits and overall growth of 12-weeks-old oak seedlings exposed to abiotic stress [low phosphorus (P) supply], biotic stress ( root infection), and their combination. The application of Si had the strongest ameliorative effect on growth, root health and root phenome under the most severe stress conditions (i.e., combination of P deficiency and root infection), where it differentially affected the uptake and leaf accumulation in 11 out of 13 analysed nutrients. Silicon supply tended to reverse the pattern of change of some, but not all, leaf nutrients affected by stresses: P, boron (B) and magnesium (Mg) under P deficiency, and P, B and sulphur (S) under pathogen attack, but also nickel (Ni) and molybdenum (Mo) under all three stresses. Surprisingly, Si affected some nutrients that were not changed by a particular stress itself and decreased leaf Mg levels under all the stresses. On the other hand, pathogen attack increased leaf accumulation of Si. This exploratory work presents the complexity of nutrient crosstalk under three stresses, and opens more questions about genetic networks that control plant physiological responses. Practically, we show a potential of Si application to improve P status and root health in oak seedlings, particularly in nurseries.
PubMed: 37705706
DOI: 10.3389/fpls.2023.1265782 -
BMC Genomics Oct 2013The interaction between insect pests and their host plants is a never-ending race of evolutionary adaption. Plants have developed an armament against insect herbivore...
BACKGROUND
The interaction between insect pests and their host plants is a never-ending race of evolutionary adaption. Plants have developed an armament against insect herbivore attacks, and attackers continuously learn how to address it. Using a combined transcriptomic and metabolomic approach, we investigated the molecular and biochemical differences between Quercus robur L. trees that resisted (defined as resistant oak type) or were susceptible (defined as susceptible oak type) to infestation by the major oak pest, Tortrix viridana L.
RESULTS
Next generation RNA sequencing revealed hundreds of genes that exhibited constitutive and/or inducible differential expression in the resistant oak compared to the susceptible oak. Distinct differences were found in the transcript levels and the metabolic content with regard to tannins, flavonoids, and terpenoids, which are compounds involved in the defence against insect pests. The results of our transcriptomic and metabolomic analyses are in agreement with those of a previous study in which we showed that female moths prefer susceptible oaks due to their specific profile of herbivore-induced volatiles. These data therefore define two oak genotypes that clearly differ on the transcriptomic and metabolomic levels, as reflected by their specific defensive compound profiles.
CONCLUSIONS
We conclude that the resistant oak type seem to prefer a strategy of constitutive defence responses in contrast to more induced defence responses of the susceptible oaks triggered by feeding. These results pave the way for the development of biomarkers for an early determination of potentially green oak leaf roller-resistant genotypes in natural pedunculate oak populations in Europe.
Topics: Animals; Cell Wall; Computational Biology; Female; Genotype; Herbivory; High-Throughput Nucleotide Sequencing; Lepidoptera; Metabolic Networks and Pathways; Metabolomics; Phenotype; Plant Leaves; Principal Component Analysis; Quercus; Sequence Analysis, RNA; Signal Transduction; Transcriptome
PubMed: 24160444
DOI: 10.1186/1471-2164-14-737 -
The New Phytologist Sep 2021Leaves interact with a wealth of microorganisms. Among these, fungi are highly diverse and are known to contribute to plant health, leaf senescence and early...
Leaves interact with a wealth of microorganisms. Among these, fungi are highly diverse and are known to contribute to plant health, leaf senescence and early decomposition. However, patterns and drivers of the seasonal dynamics of foliar fungal communities are poorly understood. We used a multifactorial experiment to investigate the influence of warming and tree genotype on the foliar fungal community on the pedunculate oak Quercus robur across one growing season. Fungal species richness increased, evenness tended to decrease, and community composition strongly shifted during the growing season. Yeasts increased in relative abundance as the season progressed, while putative fungal pathogens decreased. Warming decreased species richness, reduced evenness and changed community composition, especially at the end of the growing season. Warming also negatively affected putative fungal pathogens. We only detected a minor imprint of tree genotype and warming × genotype interactions on species richness and community composition. Overall, our findings demonstrate that warming plays a larger role than plant genotype in shaping the seasonal dynamics of the foliar fungal community on oak. These warming-induced shifts in the foliar fungal community may have a pronounced impact on plant health, plant-fungal interactions and ecosystem functions.
Topics: Ecosystem; Genotype; Mycobiome; Quercus; Seasons
PubMed: 33960441
DOI: 10.1111/nph.17434 -
G3 (Bethesda, Md.) Oct 2019The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European...
The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European forests. As a result, forests are expected to shift their distribution patterns toward north-east, which may lead to a dramatic loss in value of European forest land. Consequently, unraveling key processes that underlie drought stress tolerance is not only of great scientific but also of utmost economic importance for forests to withstand future heat and drought wave scenarios. To reveal drought stress-related molecular patterns we applied cross-species comparative transcriptomics of three major European oak species: the less tolerant deciduous pedunculate oak (), the deciduous but quite tolerant pubescent oak (), and the very tolerant evergreen holm oak (). We found 415, 79, and 222 differentially expressed genes during drought stress in , , and , respectively, indicating species-specific response mechanisms. Further, by comparative orthologous gene family analysis, 517 orthologous genes could be characterized that may play an important role in drought stress adaptation on the genus level. New regulatory candidate pathways and genes in the context of drought stress response were identified, highlighting the importance of the antioxidant capacity, the mitochondrial respiration machinery, the lignification of the water transport system, and the suppression of drought-induced senescence - providing a valuable knowledge base that could be integrated in breeding programs in the face of climate change.
Topics: Adaptation, Biological; Antioxidants; Computational Biology; Crosses, Genetic; Droughts; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Ontology; High-Throughput Nucleotide Sequencing; Molecular Sequence Annotation; Quercus; Species Specificity; Stress, Physiological; Transcriptome
PubMed: 31395652
DOI: 10.1534/g3.119.400456 -
Annals of Botany Oct 2020Highly controlled experiments document that plant genetic diversity and relatedness can shape herbivore communities and patterns of herbivory. Evidence from the field...
BACKGROUND AND AIMS
Highly controlled experiments document that plant genetic diversity and relatedness can shape herbivore communities and patterns of herbivory. Evidence from the field is, however, scarce and inconsistent. We assessed whether a genetic signal underlying herbivory can be detected in oak woodlands when accounting for variation at smaller (within-tree) and larger (among-stand) scales.
METHODS
We tested relationships between tree genetic relatedness, leaf chemical defences and insect herbivory for different canopy layers in 240 trees from 15 pedunculate oak (Quercus robur) forest stands. We partitioned sources of variability in herbivory and defences among stands, individuals and branches.
KEY RESULTS
Leaf defences, insect herbivory and their relationship differed systematically between the upper and the lower tree canopy. When accounting for this canopy effect, the variation explained by tree genetic relatedness rose from 2.8 to 34.1 % for herbivory and from 7.1 to 13.8 % for leaf defences. The effect was driven by markedly stronger relationships in the upper canopy.
CONCLUSIONS
Our findings illustrate that considerable effects of the host plant genotype on levels of leaf chemical defences and associated insect herbivory can be detected in natural tree populations when within-individual variation is properly accounted for.
Topics: Animals; Herbivory; Insecta; Plant Leaves; Quercus; Trees
PubMed: 32463869
DOI: 10.1093/aob/mcaa101 -
Tree Physiology Jul 2021We explored the timing of spring xylogenesis and its potential drivers in homogeneous mature forest stands in a temperate European region. Three species with contrasting...
We explored the timing of spring xylogenesis and its potential drivers in homogeneous mature forest stands in a temperate European region. Three species with contrasting leaf development dynamics and wood anatomy were studied: European beech, silver birch and pedunculate oak. Detailed phenological observations of xylogenesis and leaf phenology were performed from summer 2017 until spring 2018. Cambium reactivation (CR) occurred before the buds of oak and birch were swollen, whereas these two phenological phases were concurrent for beech. On the other hand, initial earlywood vessels were fully differentiated (FDIEV) after leaf unfolding for all three species. Timing of CR was correlated to average ring-width of the last 10 years (2008-17), tree diameter and, partially, with tree age. In addition, the timing of FDIEV was correlated to tree age and previous year's autumn phenology, i.e., timing of wood growth cessation and onset of leaf senescence. Multivariate models could explain up to 68% of the variability of CR and 55% of the variability of FDIEV. In addition to the 'species' factor, the variability could be explained by ca 30% by tree characteristics and previous year's autumn phenology for both CR and FDIEV. These findings are important to better identify which factors (other than environment) can be driving the onset of the growing season, and highlight the influence of tree growth characteristics and previous year's phenology on spring wood phenology, wood formation and, potentially, forest production.
Topics: Fagus; Plant Leaves; Quercus; Seasons; Trees
PubMed: 33367844
DOI: 10.1093/treephys/tpaa171 -
Plants (Basel, Switzerland) Jun 2023The conservation of the genetic resources of old trees is crucial to their ecological role but is extremely difficult, especially for oak species ( spp.) displaying...
The conservation of the genetic resources of old trees is crucial to their ecological role but is extremely difficult, especially for oak species ( spp.) displaying recalcitrance in seed and vegetative propagation methods. Our study aimed to assess the regenerative potential of trees of different ages (up to 800 years) during micropropagation. We also aimed to determine how in vitro conditions can influence in vitro regeneration responses. Lignified branches collected from 67 selected trees were cultivated ex vitro in culture pots at 25 °C to obtain epicormic shoots (explant sources). The explants were cultivated on an agar medium supplemented with 0.8 mg L 6-benzylaminopurine (BAP) for at least 21 months. In a second experiment, two different shoot multiplication conditions (temporary immersion-RITA bioreactor and agar medium) and two culture medium formulations (Woody Plant Medium and modified Quoirin and Lepoivre medium) were tested. The results showed that the mean length of the epicormic shoots obtained in a pot culture was a function of donor age and was similar among the group of younger trees (ca. 20-200 years), and varied between older trees (ca. 300-800 years). The efficiency of in vitro shoot multiplication strictly depended on the genotype. A sustainable in vitro culture (defined as survival after 6 months) was only possible for half of the tested old donor trees, even when they survived the first month of in vitro growth. A continuous monthly increase in the number of in vitro cultured shoots was reported in younger oaks and in some old oaks. We found a significant effect of the culture system and the macro- and micronutrient composition on in vitro shoot growth. This is the first report demonstrating that the in vitro culture can be successfully applied to the propagation of even 800-year-old pedunculate oak trees.
PubMed: 37375856
DOI: 10.3390/plants12122230