Evaluation of reference genes and characterization of the MYBs in xylem radial change of Chinese fir stem

The radial change (RC) of tree stem is the process of heartwood formation involved in complex molecular mechanism. Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), an evergreen species, is an important fast-growing timber tree in southern China. In this study, the top four stable genes (IDH, UBC2, RCA and H2B) were selected in RC tissues of 15 years old Chinese fir stem (RC15) and the genes (H2B, 18S, TIP41 and GAPDH) were selected in RC tissues of 30 years old Chinese fir stem (RC30). The stability of the reference genes is higher in RC30 than in RC15. Sixty-one MYB transcripts were obtained on the PacBio Sequel platform from woody tissues of one 30 years old Chinese fir stem. Based on the number of MYB DNA-binding domain and phylogenetic relationships, the ClMYB transcripts contained 21 transcripts of MYB-related proteins (1R-MYB), 39 transcripts of R2R3-MYB proteins (2R-MYB), one transcript of R1R2R3-MYB protein (3R-MYB) belonged to 18 function-annotated clades and two function-unknown clades. In RC woody tissues of 30 years old Chinese fir stem, ClMYB22 was the transcript with the greatest fold change detected by both RNA-seq and qRT-PCR. Reference genes selected in this study will be helpful for further verification of transcript abundance patterns during the heartwood formation of Chinese fir.

Fungi Associated With Woody Tissues of European Beech and Their Impact on Tree Health

Filamentous fungi associated with woody tissues of European Beech (Fagus sylvatica) and isolated from diseased trees and healthy trees were examined in relation to their impact on tree health. To this end, classical culture-based isolation methods, in planta inoculations and fungal identification using ITS-barcode and morphological characters were used. Stem endophytes of healthy beech saplings collected in German forests were isolated to determine endophyte communities in woody stem tissues. Pathogenicity tests were performed on living potted beech saplings using twelve selected fungal pathogens and wood inhabiting fungi (Hypocreales, Botryosphaeriales, and Xylariales) originating mainly from European beech with symptoms of the complex disease Vitality loss, or from bark necroses, or known to be common endophytes of beech. The impact of these ascomycetous fungi with respect to tree health was discussed. The potential influences of endophytic fungi of beech and of test conditions are discussed in relation to the success of inoculation. All tested fungal strains except for Neonectria ditissima were able to establish themselves post inoculation in the beech stems and caused necroses when there was sufficient water, but at different severities. Under the experimental conditions, Botryosphaeria corticola was shown to be the most virulent tested latent pathogen against F. sylvatica. In the context of climate change and global warming, the tested Botryosphaeriaceae are able to play a primary role in the disease progress of Vitality loss of Beech. The key role of Neonectria coccinea in causing bark necroses and the loss of vitality in beech was confirmed because the tested strain induced large lesions on the beech saplings.

Impacts of Sodium Arsenite on Wood Microbiota of Esca-Diseased Grapevines

Although sodium arsenite was widely used in Europe until its ban in 2003, its effects on microorganisms is not clearly understood. To improve our understanding of sodium arsenite curative effect on GTDs, grapevines displaying esca-foliar symptoms from different French regions (Alsace, Champagne, Languedoc) were treated or not with sodium arsenite, and analyzed for their wood microbiota. Using metabarcoding, we identified the fungal and bacterial taxa composition of microbiota colonizing woody trunk tissues. Large differences in fungal microbiota composition between treated and untreated grapevines were observed while no major impacts were observed on bacteria microbiota. The main fungal species detected in untreated necrotic woody tissues was Fomitiporia mediterranea (63–94%), a fungal pathogen associated with esca. The relative abundance of this fungal species significantly decreased after sodium arsenite treatment in the three vineyards, in particular in white-rot necrotic tissues and their borders (−90%). F. mediterranea was the most sensitive to sodium arsenite among fungi from grapevine woody tissues. These results strongly suggest that the effect of sodium arsenite on GTDs is due to its ability to efficiently and almost specifically eliminate F. mediterranea from white-rot necrotic tissues, allowing saprobic fungi to colonize the tissues previously occupied by this pathogenic fungus.

Further Investigation on Limb Dieback of Fig (Ficus carica) Caused by Neoscytalidium dimidiatum in California

Fig limb dieback is a cosmopolitan disease caused by Neoscytalidium dimidiatum (Botryosphaeriaceae), characterized by branch and shoot cankers, discoloration of woody tissues, and dieback. The present study investigated the etiology of the disease in California that seems to have become prevalent among fig orchards in the last several years. During orchard surveys in Fresno, Kern, and Madera Counties over 3 years, we isolated consistently and evaluated the pathogenicity of N. dimidiatum under laboratory and field conditions. The effect of summer and winter pruning on the disease severity and the effects of different environmental and mechanical stresses, such as sunburn and wounding by mallets, were assayed. In addition, the susceptibility of six different cultivars and the effects of eradicating cankered shoots from the fig trees as a method to combat the spread of the disease were studied. Pathogenicity tests demonstrated that N. dimidiatum induces cankers on fig, mainly on wounded shoots. Results from the remaining experiments revealed that summer infection leads to more severe canker lesions than those induced by winter infection and that stressed shoots are more susceptible to infection than nonstressed shoots. ‘Brown Turkey’, ‘Conadria’, and ‘Calimyrna’ cultivars (all nonpersistent figs, i.e., needing pollination for fruit development) were less susceptible than the more susceptible ‘Kadota’, ‘Sierra’, and ‘Black Mission’ (all persistent figs, i.e., not needing pollination for fruit development). Canker removal from the orchard seems to be a good agronomic practice to avoid the spread of disease.

Forest – the photosphere of life in the Earth’s atmosphere

The evolution of the vertical, long distance water transport, overcoming gravitation, by trees during the Devonian, initiated the emerging of forest ecosystems extending the photosphere of life further into the Earth's atmosphere. The origin of woody tissues is likely associated with genome mutations in primitive green plants, which inhabited the land about 350 million years ago. Most probably, only two mutations were required – one allowing the synthesis of lignin and the second, enabling the autolysis of protoplast in the maturing cellular woody elements. Developing forest ecosystems formed the most productive environments, in which sunlight-dependent metabolic processes of life reached further into the atmosphere while at the same time allowing more water to be stored on the land surface, which in turn allowed for the evolution of numerous heterotrophic organisms. This property of the forest could therefore be considered an important factor in the evolution of hominids, which eventually contributed to the development of the Homo sapiens culture.

Studying in vivo dynamics of xylem-transported 11CO2 using positron emission tomography

Respired CO2 in woody tissues can build up in the xylem and dissolve in the sap solution to be transported through the plant. From the sap, a fraction of the CO2 can either be radially diffuse to the atmosphere or be assimilated in chloroplasts present in woody tissues. These processes occur simultaneously in stems and branches, making it difficult to study their specific dynamics. Therefore, an 11C-enriched aqueous solution was administered to young branches of Populus tremula L., which were subsequently imaged by positron emission tomography (PET). This approach allows in vivo visualization of the internal movement of CO2 inside branches at high spatial and temporal resolution, and enables direct measurement of the transport speed of xylem-transported CO2 (vCO2). Through compartmental modeling of the dynamic data obtained from the PET images, we (i) quantified vCO2 and (ii) proposed a new method to assess the fate of xylem-transported 11CO2 within the branches. It was found that a fraction of 0.49 min−1 of CO2 present in the xylem was transported upwards. A fraction of 0.38 min−1 diffused radially from the sap to the surrounding parenchyma and apoplastic spaces (CO2,PA) to be assimilated by woody tissue photosynthesis. Another 0.12 min−1 of the xylem-transported CO2 diffused to the atmosphere via efflux. The remaining CO2 (i.e., 0.01 min−1) was stored as CO2,PA, representing the build-up within parenchyma and apoplastic spaces to be assimilated or directed to the atmosphere. Here, we demonstrate the outstanding potential of 11CO2-based plant-PET in combination with compartmental modeling to advance our understanding of internal CO2 movement and the respiratory physiology within woody tissues.

Carbon and nitrogen accumulation within four black walnut alley cropping sites across Missouri and Arkansas, USA

Agroforestry systems that integrate useful long-lived trees have been recognized for their potential in mitigating the accumulation of atmospheric fossil fuel-derived carbon (C). Black walnut (Juglans nigra) is frequently planted and cultivated in North America for its valuable lumber and edible nuts, and is highly amenable to the integration of understory crops or livestock in agroforestry systems. However, little is known about C content in black walnut trees, including the amounts of C assimilated into lignocellulosic tissues within different tree compartments. Therefore, allometric equations for above- and below-ground compartments of 10-year-old black walnut trees across diverse locations were developed. Ten grafted black walnut trees from each of four sites across the midwestern USA were destructively harvested for above- and below-ground biomass, and dry biomass weight (DWw), C (Cw) and nitrogen (N; Nw) stocks were quantified. Soils surrounding the harvested trees were sampled and analyzed for soil organic C (SOC) and total N (TN). Total DWw ranged from 27 to 54 kg tree−1, with woody tissues containing an average of 467 g kg−1 C and 3.5 g kg−1 N. Woody tissues differed in Cw and Nw across location, and above-ground sections contained more C and less N compared with most root tissues. The slopes of the allometric equations did not differ significantly among locations, while intercepts did, indicating that trees only differed in initial size across locations. SOC and TN did not vary in distance from the trees, likely because the trees were not yet old enough to have impacted the surrounding soils. Our results establish a foundation for quantifying C and N stocks in newly established black walnut alley cropping systems across diverse environments.

Charcoalified Wood of Hopenium pondicherriensis (Dipterocarpaceae) from Neyveli Lignite Formation

The Neyveli lignite is one of the largest brown coal field of India, Cuddalore district of Tamil Nadu. The lignite it is one of tertiary formation found in the Neyveli, So far many mega and micro fossils reported from this formation. The Neyveli lignite well preserved and recognizable entities are mainly woody and non-woody tissues of different angiosperm plants, spore and pollen, cuticles of leaves, resins, fungal spores and fungal fruiting bodies. The present study is about the charcoalified angiospermic wood is identified as Hopenium pondicherriensis (Dipterocarpaceae). This is a first report of Hopenium pondicherriensis from the Neyveli formation.

The Common Natural Products (S)-α-Terpineol and (E)-2-Hexenol are Important Pheromone Components of Megacyllene antennata (Coleoptera: Cerambycidae)

We report here the pheromone of Megacyllene antennata (White) (Coleoptera: Cerambycidae), a species native to southwestern North America whose larvae feed in woody tissues of mesquite (Prosopis species; Fabaceae). Adult males sex-specifically produced a blend of eight common natural products, including the monoterpene alcohol (S)-α-terpineol; the monoterpenes (S)-limonene and terpinolene; the aromatic alcohols (R)-1-phenylethanol and 2-phenylethanol; and (E)-2-hexenol, (E)-2-hexenal, and 1-hexanol. Individual males produced the components in varying amounts, but (S)-α-terpineol and (E)-2-hexenal were always present and together constituted the majority of the blend. A synthetic reconstruction of the complete blend attracted both males and females of M. antennata during field bioassays, as did all subsets of the blend that included (S)-α-terpineol and (E)-2-hexenol. Adults were most strongly attracted to blends of the latter two compounds when in ratios approaching parity. Neither of the compounds were present in the bouquet of volatiles emitted by host plants of the larvae.