This study aims to identify candidate genes involved in the biosynthesis of salicinoid phenolic glycosides (SPGs), a group of specialised metabolites characteristic of the Salicaceae family. While the integration of multi-omics data represents a powerful approach to link genes encoding enzymes and their regulatory factors to metabolite biosynthesis, suitable multi-omics data resources are scarce. We present a comprehensive dataset comprising untargeted liquid chromatography-mass spectrometry (LC-MS) and mRNA-sequencing data from various organs of European aspen (Populus tremula L.) and from genotypes that produce contrasting sets of SPGs. We present a reproducible pipeline for the analysis of the LC-MS data, including predicted annotation of potential novel SPGs. We demonstrate the utility of the resource by identifying candidate genes involved in the biosynthesis of SPGs with a cinnamoyl moiety. By integrating gene and metabolite differential analyses with a gene co-expression network, we identified two HXXXD-type acyltransferase genes and one UDP-glucosyltransferase gene as candidates for future downstream characterisation. The combined gene expression and metabolomics resource is integrated into PlantGenIE.org to facilitate easy access and data mining. All raw data are available in public databases, and all data and results files are available at an associated Figshare repository.

Achieving optimal nutrient composition in locally sourced ruminant feeds is important, but can be challenging in resource-limited production systems. For example, improving the composition of available local feed resources is a key obstacle to efficiently mitigating enteric methane (CH4) emissions in ruminants. This study characterized the nutritional content and in vitro methane (CH4) yield of ruminant feedstuffs accessible in Ethiopia.A survey of 60 experienced farmers in two representative districts in Amhara region, Ethiopia, provided 33 feed samples, which were classified into four ruminant feed categories: Grasses (n=10); indigenous plants (trees, shrubs, herbaceous plants) (n=13); crop residues (n=5); and agro-industrial by-products (n=5). Nutritional composition was assessed by proximate and detergent methods. Methane yield (g CH4/kg feed dry matter (DM)) and total gas yield (L/kg DM) were evaluated using a fully automated in vitro gas production system. A colorimetric assay was conducted to measure condensed tannin content (CT, mg/g) in relevant feeds.Lower crude protein (CP) values were observed for the grass (mean 65.2g/kg DM) and crop residues (mean 54.5g/kg DM) categories. Agro-industrial by-products had the highest CP (mean 260g/kg DM), while indigenous plants exhibited intermediate levels (163g/kg DM).There was significant variation in CH4 yield (P<0.01) between grasses (12.4-24.7g/kg DM) indigenous plants (1.8-19.3g/kg DM), and agro-industrial by-products (8.1-26.9g/kg DM). The indigenous plant Trifolium acaule gave the lowest in vitro CH4 yield (1.8g/kg DM).A positive relationship was observed between in vitro dry matter digestibility (IVDMD), CH4, and total gas yield. Percentage of CH4 in total gas production varied with feed category (grasses 14.5-19.6%; indigenous plants 3.1-16.9%; crop residues 15.8-20.6%; agro-industrial by-products 12.8-18.7%), and within category, e.g., Trifolium acaule (3.1%), Acacia nilotica L. (7.1%), Ziziphus spina-christi (9.9%), brewer’s spent grains (BSG) (12.8%), local liquor (areki) residues (14.1%), and local beer (tella) residues (15.1%).A negative relationship was observed between CT content and in vitro CH4 yield, with a stronger (P<0.05) correlation for soluble CTs (R2 = 0.46) than cell-bound CTs (R2 = 0.25) and total CTs (R2 = 0.29). Based on methanogenic properties and effects of CTs on in vitro CH4 yield, indigenous plants should be prioritized in ruminant rations in Ethiopia. Making nutritional composition and CH4 data publicly available could help develop environmentally sound, cost-effective rations for ruminant livestock, benefiting local farmers and leading to more sustainable and efficient livestock production in Ethiopia.

Background Plant mycobiomes play a crucial role in plant health, growth, and adaptation to changing environments, making their diversity and dynamics essential for agricultural and environmental contexts, including conservation efforts, climate change mitigation, and potential biotechnological applications. Horizontally transferred mycobiomes are established in plant organs, yet the dynamics of their colonization and establishment remain unknown. New molecular technologies offer a deeper insight into the establishment and dynamics of plant-associated mycobiomes. In this study, we investigated leaf-associated mycobiomes in cloned replicates of aspen (Populus tremula) with naturally varying phenolic profiles and a history of nitrogen fertilization. Main findings Using ITS2 metabarcoding of 344 samples collected from a ca ten-year-old common garden with small aspen trees at various time points over two consecutive years, we identified 30,080,430 reads in our database, corresponding to an average of 87,448 reads per sample clustered into 581 amplicon sequence variants (ASVs). Analysis of ASV patterns revealed changes in both richness and abundance among genotypes and across the seasons, with no discernible effect of fertilization history. Additionally, the number of reads was negatively correlated with the ability of the genotypes to synthesize and store condensed tannins.

EDITORIAL article Front. Plant Sci., 15 February 2023Sec. Crop and Product Physiology Volume 14 - 2023 | https://doi.org/10.3389/fpls.2023.1143571

Forests are at increasing risk from pathogen outbreak. Climate change for example enhance the risk of local disease outbreaks, and naturalization of exotic pathogens may follow human activities, warranting robust pest surveillance routines to support forest management. Melampsora pinitorqua (pine twisting rust) is of concern in Swedish forestry, and here we evaluate the use of visible rust scores (VRS) on its obligate summer host, European aspen (Populus tremula) as a tool for quantification of the pathogen. With use of species-specific primers, we could detect the native rust, but we failed to detect two exotic rusts (M. medusae and M. larici-populina). We found that aspen genotype determined the presence of fungal genetic markers (amplifying the ITS2 region of the fungal rDNA sequence) as well as DNA sequences specific to M. pinitorqua. We correlated VRS with the amount of fungal DNA in the same leaf, and we related the findings to aspen genotype-specific parameters such as the ability to synthesize and store leaf condensed tannins (CT). At the genotype level both positive and negative relationships were observed between CTs, fungal markers, and rust infestations. However, at the population level, foliar CT concentrations correlated negatively with general fungal- and rust-specific marker abundances. Our results, therefore, do not support the use of VRS to assess Melampsora infestation in Aspen. They do, however, suggest that the relationship between European aspen and rust infestation may be characterized as autochthonous in northern Sweden.

Proanthocyanidins (PAs) are polymeric phenolic compounds found in plants and used in many industrial applications. Despite strong evidence of herbivore and pathogen resistance-related properties of PAs, their in planta function is not fully understood. Determining the location and dynamics of PAs in plant tissues and cellular compartments is crucial to understand their mode of action. Such an approach requires microscopic localization with fluorescent dyes that specifically bind to PAs. Such dyes have hitherto been lacking. Here, we show that 4-dimethylaminocinnamaldehyde (DMACA) can be used as a PA-specific fluorescent dye that allows localization of PAs at high resolution in cell walls and inside cells using confocal microscopy, revealing features of previously unreported wall-bound PAs. We demonstrate several novel usages of DMACA as a fluorophore by taking advantage of its double staining compatibility with other fluorescent dyes. We illustrate the use of the dye alone and its co-localization with cell wall polymers in different Populus root tissues. The easy-to-use fluorescent staining method, together with its high photostability and compatibility with other fluorogenic dyes, makes DMACA a valuable tool for uncovering the biological function of PAs at a cellular level in plant tissues. DMACA can also be used in other plant tissues than roots, however care needs to be taken when tissues contain compounds that autofluoresce in the red spectral region which can be confounded with the PA-specific DMACA signal.

Xylan that comprises roughly 25% of hardwood biomass is undesirable in biorefinery applications involving saccharification and fermentation. Efforts to reduce xylan levels have therefore been made in many species, usually resulting in improved saccharification. However, such modified plants have not yet been tested under field conditions. Here we evaluate the field performance of transgenic hybrid aspen lines with reduced xylan levels and assess their usefulness as short-rotation feedstocks for biorefineries. Three types of transgenic lines were tested in four-year field tests with RNAi constructs targeting either Populus GT43 clades B and C (GT43BC) corresponding to Arabidopsis clades IRX9 and IRX14, respectively, involved in xylan backbone biosynthesis, GATL1.1 corresponding to AtGALT1 involved in xylan reducing end sequence biosynthesis, or ASPR1 encoding an atypical aspartate protease. Their productivity, wood quality traits, and saccharification efficiency were analyzed. The only lines differing significantly from the wild type with respect to growth and biotic stress resistance were the ASPR1 lines, whose stems were roughly 10% shorter and narrower and leaves showed increased arthropod damage. GT43BC lines exhibited no growth advantage in the field despite their superior growth in greenhouse experiments. Wood from the ASPR1 and GT43BC lines had slightly reduced density due to thinner cell walls and, in the case of ASPR1, larger cell diameters. The xylan was less extractable by alkali but more hydrolysable by acid, had increased glucuronosylation, and its content was reduced in all three types of transgenic lines. The hemicellulose size distribution in the GALT1.1 and ASPR1 lines was skewed towards higher molecular mass compared to the wild type. These results provide experimental evidence that GATL1.1 functions in xylan biosynthesis and suggest that ASPR1 may regulate this process. In saccharification without pretreatment, lines of all three constructs provided 8-11% higher average glucose yields than wild-type plants. In saccharification with acid pretreatment, the GT43BC construct provided a 10% yield increase on average. The best transgenic lines of each construct are thus predicted to modestly outperform the wild type in terms of glucose yields per hectare. The field evaluation of transgenic xylan-reduced aspen represents an important step towards more productive feedstocks for biorefineries.

Genes involved in plant defences against herbivores and pathogens are often highly polymorphic. This is a putative sign that balancing selection may have operated reciprocally on the hosts and their herbivores. Spatial and temporal variations (for example, in soil nutrients and the plants' ontogenetic development) may also modulate resistance traits, and thus selection pressures, but have been largely overlooked in theories of plant defences. Important elements of defences in Populus tremula (hereafter aspen) are phenolic compounds, including condensed tannins (CTs). Concentrations of CTs vary considerably with both variations in external factors and time, but they are also believed to provide genotype-dependent resistance, mainly against chewing herbivores and pathogens. However, evidence of their contributions to resistance is sparse. Detailed studies of co-evolved plant-herbivore associations could provide valuable insights into these contributions. Therefore, we examined correlations between CT levels in aspen leaves and both the feeding behavior and reproduction of the specialist aspen leaf aphid (Chaitophorus tremulae) in varied conditions. We found that xylem sap intake and probing difficulties were higher on genotypes with high-CT concentrations. However, aphids engaged in more nonprobing activities on low-CT genotypes, indicating that CTs were not the only defence traits involved. Thus, high-CT genotypes were not necessarily more resistant than low-CT genotypes, but aphid reproduction was generally negatively correlated with local CT accumulation. Genotype-specific resistance ranking also depended on the experimental conditions. These results support the hypothesis that growth conditions may affect selection pressures mediated by aphids in accordance with balancing selection theory.

Condensed tannins (CTs) are polyphenolics and part of the total phenolic (TP) pool that shape resistance in aspen (Populus tremula). CTs are negatively associated with pathogens, but their resistance properties against herbivores are less understood. CTs shape resistance to pathogens and chewing herbivores and could also shape resistance to aphids. Being chemical pools that are highly variable it can further be questioned whether CT-shaped resistance is better described by constitutive levels, by the induced response potential, or by both. Here, aspen genotypes were propagated and selected to represent a range of inherent abilities to produce and store foliar CTs; the plantlets were then exposed to Chaitophorus aphid infestation and to mechanical (leaf rupture) damage, and the relative abundance of constitutive and induced CTs was related to aphid fitness parameters. As expected, aphid fecundity was negatively related to CT-concentrations of the aphid infested plants although more consistently related to TPs. While TPs increased in response to damage, CT induction was generally low and it even dropped below constitutive levels in more CT-rich genotypes, suggesting that constitutive CTs are more relevant measurements of resistance compared to induced CT-levels. Relating CT and TP dynamics with phenolic low molecular compounds further suggested that catechin (the building block of CTs) increased in response to aphid damage in amounts that correlated negatively with CT-induction and positively with constitutive CT-levels and aphid fecundity. Our study portrays dynamic phenolic responses to two kinds of damage detailed for major phenylpropanoid classes and suggests that the ability of a genotype to produce and store CTs may be a measurement of resistance, caused by other, more reactive, phenolic compounds such as catechin. Rupture damage however appeared to induce catechin levels oppositely supporting that CTs may respond differently to different kinds of damage.

Abiotic and biotic factors may shape the mycobiome communities in plants directly but also indirectly by modifying the quality of host plants as a substrate. We hypothesized that nitrogen fertilization (N) would determine the quality of aspen (Populus tremula) leaves as a substrate for the endophytic fungi, and that by subjecting the plants to N, we could manipulate the concentrations of positive (nutritious) and negative (antifungal) chemicals in leaves, thus changing the internal “chemical landscape” for the fungi. We expected that this would lead to changes in the fungal community composition, in line with the predictions of heterogeneity–diversity relationship and resource availability hypotheses. To test this, we conducted a greenhouse study where aspen plants were subjected to N treatment. The chemical status of the leaves was confirmed using GC/MS (114 metabolites, including amino acids and sugars), LC/MS (11 phenolics), and UV-spectrometry (antifungal condensed tannins, CTs), and the endophytic communities were characterized using culture-dependent sequencing. We found that N treatment reduced foliar concentrations of CT precursor catechin but not that of CTs. Nitrogen treatment also increased the concentrations of the amino acids and reduced the concentration of some sugars. We introduced beetle herbivores (H) as a second treatment but found no rapid changes in chemical traits nor strong effect on the diversity of endophytes induced by herbivores. A few rare fungi were associated with and potentially vectored by the beetle herbivores. Our findings indicate that in a controlled environment, the externally induced changes did not strongly alter endophyte diversity in aspen leaves.

High-Throughput Illumina Sequencing (HTS) can be used to study metagenomes, for example, those of importance for plant health. However, protocols must be optimized according to the plant system in question, the focal microorganisms in the samples, the marker genes selected, and the number of environmental samples. We optimized the protocol for metagenomic studies of aspen leaves, originating from varied genotypes sampled across the growing season, and consequently varying in phenolic composition and in the abundance of endo- and epiphytic fungal species. We optimized the DNA extraction protocol by comparing commercial kits and evaluating five fungal ribosomal specific primers (Ps) alone, and with extended primers that allow binding to sample-specific index primers, and we then optimized the amplification with these composite Ps for 380 samples. The fungal DNA concentration in the samples varied from 561 ng/µL to 1526 ng/µL depending on the DNA extraction kit used. However, binding to phenolic compounds affected DNA quality as assessed by Nanodrop measurements (0.63–2.04 and 0.26–2.00 absorbance ratios for 260/280 and 260/230, respectively), and this was judged to be more important in making our choice of DNA extraction kit. We initially modified the PCR conditions after determining the concentration of DNA extract in a few subsamples and then evaluated and optimized the annealing temperature, duration, and number of cycles to obtain the required amplification and PCR product bands. For three specific Ps, the extended Ps produced dimers and unexpected amplicon fragments due to nonspecific binding. However, we found that the specific Ps that targeted the ITS2 region of fungal rDNA successfully amplified this region for every sample (with and without the extension PP) resulting in the desired PCR bands, and also allowing the addition of sample-specific index primers, findings which were successfully verified in a second PCR. The optimized protocol allowed us to successfully prepare an amplicon library in order to subject the intended 380 environmental samples to HTS.

Following a pathogen attack, plants defend themselves using multiple defense mechanisms to prevent infections. We used a meta-analysis and systems-biology analysis to search for general molecular plant defense responses from transcriptomic data reported from different pathogen attacks in Arabidopsis thaliana. Data from seven studies were subjected to meta-analysis, which revealed a total of 3694 differentially expressed genes (DEGs), where both healthy and infected plants were considered. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis further suggested that the DEGs were involved in several biosynthetic metabolic pathways, including those responsible for the biosynthesis of secondary metabolites and pathways central to photosynthesis and plant–pathogen interactions. Using network analysis, we highlight the importance of WRKY40, WRKY46 and STZ, and suggest that they serve as major points in protein–protein interactions. This is especially true regarding networks of composite-metabolic responses by pathogens. In summary, this research provides a new approach that illuminates how different mechanisms of transcriptome responses can be activated in plants under pathogen infection and indicates that common genes vary in their ability to regulate plant responses to the pathogens studied herein.

Plants interact with a multitude of microorganisms and insects, both below- and above ground, which might influence plant metabolism. Despite this, we lack knowledge of the impact of natural soil communities and multiple aboveground attackers on the metabolic responses of plants, and whether plant metabolic responses to single attack can predict responses to dual attack. We used untargeted metabolic fingerprinting (gas chromatography-mass spectrometry, GC-MS) on leaves of the pedunculate oak, Quercus robur , to assess the metabolic response to different soil microbiomes and aboveground single and dual attack by oak powdery mildew ( Erysiphe alphitoides ) and the common oak aphid ( Tuberculatus annulatus ). Distinct soil microbiomes were not associated with differences in the metabolic profile of oak seedling leaves. Single attacks by aphids or mildew had pronounced but different effects on the oak leaf metabolome, but we detected no difference between the metabolomes of healthy seedlings and seedlings attacked by both aphids and powdery mildew. Our findings show that aboveground attackers can have species-specific and non-additive effects on the leaf metabolome of oak. The lack of a metabolic signature detected by GC-MS upon dual attack might suggest the existence of a potential negative feedback, and highlights the importance of considering the impacts of multiple attackers to gain mechanistic insights into the ecology and evolution of species interactions and the structure of plant-associated communities, as well as for the development of sustainable strategies to control agricultural pests and diseases and plant breeding.

Arthropod herbivore assemblages are used to gain insight into questions about evolution, ecology, diversity, and conservation. However, determination at the species level of small arthropods may be challenging risking underestimating diversity. Here we suggest morphometric analyses as a supplementary determination method, and we demonstrate its use for a study of Chaitophorus species collected from Aspen trees ( Populus tremula ). Although sampled as one colony, the aphids represented three species. Rearing the species separately allowed us to get estimates characteristic of the developmental stages from each of the three species for morphometric comparisons. Recursive partitioning (RP) was used to create a decision tree for choice of morphometric parameters that with significance (p < 0.05) could determine the aphids by species and developmental stage; this insight could then be used as a key for determination. Eight of fifteen morphometric traits were selected by RP to be used in the key. Body length was responsible for nine splits and was consequently the more consistent morphometric trait used in the key.

Resistance (R) genes usually compete in a coevolutionary arms race with reciprocal effectors to confer strain-specific resistance to pathogens or herbivorous insects. Here, we investigate the specificity of SLI1, a recently identified R gene in Arabidopsis that encodes a small heat shock-like protein involved in resistance to Myzus persicae aphids. In a panel with several aphid and whitefly species, SLI1 compromised reproductive rates of three species: the tobacco aphid M. persicae nicotianae, the cabbage aphid Brevicoryne brassicae and the cabbage whitefly Aleyrodes proletella. Electrical penetration graph recording of aphid behaviour, revealed shorter salivations and a 3-to-5-fold increase in phloem feeding on sli1 loss-of-function plants. The mustard aphid Lipaphis erysimi and Bemisia tabaci whitefly were not affected by SLI1. Unlike the other two aphid species, L. erysimi exhibited repetitive salivations preceding successful phloem feeding, indicating a role of salivary effectors in overcoming SLI1-mediated resistance. Microscopic characterization showed that SLI1 proteins localize in the sieve tubes of virtually all above- and below-ground tissues and co-localize with the aphid stylet tip after penetration of the sieve element plasma membrane. These observations reveal an unconventional R gene that escapes the paradigm of strain specificity and confers broad-spectrum quantitative resistance to phloem-feeding insects.

Boreal forests receive nitrogen-(N)-enrichment via atmospheric deposition and industrial fertilization. While it is known that N-enrichment can intensify interactions with natural antagonists, it remains poorly understood how genetic variability in plant defense chemistry can affect biotic interactions and height growth in N-enriched environments. We grew replicates of five low-and high-tannin Populus tremula genotypes, respectively, under three N-treatments (ambient, 15, and 150 kg N ha(-1) yr(-1)). We assessed shoot blight occurrence (i.e. symptoms caused by Venturia fungi) during four growing seasons, and tree height growth during the same period. Damage by Venturia spp. increased with N-addition during all years, likely due to enhanced foliar quality. Low-tannin plants showed higher incidences of Venturia infection than high-tannin plants, regardless of the N-input-level. Height responded to an N-by-tannin-group interaction, which occurred because high-tannin plants grew taller than low-tannin plants at the high N-treatment, but not under the other N-levels. This pattern indicates that innate resource investment into tannin production yields a positive effect on growth under N-enriched conditions. Given that N-deposition is increasing globally, our research suggests that further studies are needed to investigate how N-enrichment interacts with plant defense traits globally. Moreover, our research suggests that N-deposition may provide an advantage for well-defended, high-tannin plants; and further, that genetic diversity in plant defense may be a key mechanism by which plant populations respond to this change.

Beech trees (Fagus sylvatica) are prominent keystone species of great economic and environmental value for central Europe, hosting a diverse mycobiome. The composition of endophyte communities may depend on tree health, plant organ or tissue, and growth habitat. To evaluate mycobiome communalities at local scales, buds, and twigs were sampled from two young healthy mountain beech stands in Bavaria, Germany, four kilometers apart. With Illumina high-throughput sequencing, we found 113 fungal taxa from 0.7 million high-quality reads that mainly consisted of Ascomycota (52%) and Basidiomycota (26%) taxa. Significant correlations between richness and diversity indices were observed (p < 0.05), and mycobiomes did not differ between habitats in the current study. Species richness and diversity were higher in twigs compared to spring buds, and the assemblages in twigs shared most similarities. Interaction network analyses revealed that twig-bound fungi shared similar numbers of (interaction) links with others, dominated by negative co-occurrences, suggesting that competitive exclusion may be the predominant ecological interaction in the highly connected twig mycobiome. Combining community and network analyses strengthened the evidence that plant organs may filter endophytic communities directly through colonization access and indirectly by facilitating competitive interactions between the fungi.

In this study, physiological and molecular responses of sage (Salvia officinalis) to silver nanoparticles (SNPs) were studied. It is supposed that sage oxidative responses can be activated to overcome the negative effects of SNPs. Results showed the penetration of SNPs via leaf epidermis into the parenchyma cells after foliar application. A significant decrease of photosynthetic pigments and increase of cell injury indicators, the activity of enzymatic antioxidants and also the content of non‐enzymatic antioxidants were observed after exposure of sage plants to 50 and 1000 mg l−1 SNPs compared to control plants. Phenolic compounds generally increased, but not in linear response to the dose level. The most abundant phenolic acid, rosmarinic acid (RA), increased more than eightfold at 100 mg l−1 SNPs. Furthermore, the content of RA, salvianolic acid A and B was positively correlated with the activity of phenylalanine ammonia‐lyase and RA synthase, but not with tyrosine aminotransferase. It could be concluded that the content of phenolic compounds increased in response to lower SNPs concentrations (50 and 100 mg l−1). However, the oxidative stress responses continued above these concentrations.

The production of biofuels and "green" chemicals from the lignocellulose of fast-growing hardwood species is hampered by extensive acetylation of xylan. Different strategies have been implemented to reduce xylan acetylation, resulting in transgenic plants that show good growth in the greenhouse, improved saccharification and fermentation, but the field performance of such plants has not yet been reported. The aim of this study was to evaluate the impact of reduced acetylation on field productivity and identify the best strategies for decreasing acetylation. Growth and biological stress data were evaluated for 18 hybrid aspen lines with 10-20% reductions in the cell wall acetyl content from a five year field experiment in Southern Sweden. The reduction in acetyl content was achieved either by suppressing the process of acetylation in the Golgi by reducing expression of REDUCED WALL ACETYLATION (RWA) genes, or by post-synthetic acetyl removal by fungal acetyl xylan esterases (AXEs) from two different families, CE1 and CE5, targeting them to cell walls. Transgene expression was regulated by either a constitutive promoter (35S) or a wood-specific promoter (WP). For the majority of transgenic lines, growth was either similar to that in WT and transgenic control (WP:GUS) plants, or slightly reduced. The slight reduction was observed in the AXE-expressing lines regulated by the 35S promoter, not those with the WP promoter which limits expression to cells developing secondary walls. Expressing AXEs regulated by the 35S promoter resulted in increased foliar arthropod chewing, and altered condensed tannins and salicinoid phenolic glucosides (SPGs) profiles. Greater growth inhibition was observed in the case of CE5 than with CE1 AXE, and it was associated with increased foliar necrosis and distinct SPG profiles, suggesting that CE5 AXE could be recognized by the pathogen-associated molecular pattern system. For each of three different constructs, there was a line with dwarfism and growth abnormalities, suggesting random genetic/epigenetic changes. This high frequency of dwarfism (17%) is suggestive of a link between acetyl metabolism and chromatin function. These data represent the first evaluation of acetyl-reduced plants from the field, indicating some possible pitfalls, and identifying the best strategies, when developing highly productive acetyl-reduced feedstocks.

Plants constantly interact with numerous of organisms and the outcome of these interactions determines plant health and growth. In other words, the phenotype of a plant is not only the result of the plant’s interaction with abiotic conditions, but also of multiple interactions in the living environment surrounding the plant, the phytobiome. In this Teaching Tool, we have focused on interactions between plants, microbes and arthropods (PMA). The organism groups that contribute to PMA interactions are presented as well as types of interactions between them, along with multiple examples of simple and more complex PMA interactions. The underlying mechanisms of plant responses are described in detail as well as the evolutionary aspects of PMA interactions. Finally, the use of PMA interactions for crop protection in sustainable plant production that supports the UN Sustainable Development Goals for 2030 is proposed.