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<jats:p>Hessian fly (HF), <jats:italic>Mayetiola destructor</jats:italic>, is a major insect pest that causes severe losses in grain yield and quality of wheat (<jats:italic>Triticum aestivum</jats:italic>). Growing resistant cultivars is the most cost-effective approach to minimize wheat yield losses caused by HF. In this study, 2,496 wheat accessions were screened for resistance to the HF biotype ‘Great Plains’ (GP) in the greenhouse experiments. To purify seeds from heterogeneous resistant accessions, we recovered single resistant plants from 331 accessions that had at least one resistant plant after HF infestation of a global collection of 1,595 accessions and confirmed 27 accessions with high resistance (HR), and 91 accessions with moderate resistance (MR) to the GP biotype using purified seeds. Screening of 203 U.S. winter wheat accessions in three experiments identified 63 HR and 28 MR accessions; and screening of three additional Asian panels identified 4 HR and 25 MR accessions. Together, this study identified 96 HR accessions and 144 MR accessions. Analysis of the geographic distribution of these HR and MR accessions revealed that these countries with HF as a major wheat pest usually showed higher frequencies of resistant accessions, with the highest frequency of HR (81.3%) and MR (30.6%) accessions identified from the U.S. In addition, phenotyping of 39 wheat accessions that carry known HF resistance genes showed that all the accessions except <jats:italic>H1H2</jats:italic> remain effective against GP biotype. Some of these newly identified resistant accessions may contain new HF resistance genes and can be valuable sources for developing HF resistant wheat cultivars.</jats:p>

<jats:p><jats:italic>Paris polyphylla</jats:italic> var. <jats:italic>yunnanensis</jats:italic>, a well-known Chinese medicinal herb, shows a unique physiological trait characterized by the cyclic opening and closing of its anthers after pollen maturation. The aim of this study was to explore the implications of this phenomenon on breeding. RNA sequencing coupled with methylation sequencing was used to scrutinize and compare gene expression profiles and methylation alterations in pollen and seeds during anther opening and closing, along with cold exposure. Genes enriched within Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were examined to identify gene clusters susceptible to temperature-related methylation changes in both pollen and seeds. Four pollen treatment models, namely, normal control, “pollen protected from low temperatures,” “pollen from just-opened anther,” and “pollen from close-blocked anther,” were used to produce corresponding seeds via artificial pollination. Subsequently, qRT-PCR was used to validate modifications in the expression patterns of marker genes in pollinated seeds under diverse treatment scenarios. Genes exhibiting significant differences in expression between anthers and normal tissues, along with gene regions linked to methylation variations attributed to low-temperature-treated pollen and seeds, were identified through transcriptomic analysis. Convergence was observed in three signaling pathways: oxidative phosphorylation (ko00190), plant hormone signal transduction (Ko04075), and zeatin biosynthesis (ko00908). Notably, gene clusters prone to temperature-induced methylation changes, such as NADH-ubiquinone oxidoreductase chain 5, plasma membrane ATPase 4, cytochrome c oxidase subunit 2, cis-zeatin O-glucosyltransferase, ABSCISIC ACID-INSENSITIVE 5-like protein 4, and indole-3-acetic acid-amido synthetase (IAAS), were identified. Evaluation using various pollen pollination models revealed altered expression patterns of five dormancy-regulating marker genes: IAAS, sucrose synthase (SUS), gibberellin 2-oxidase (GA2ox), ABA INSENSITIVE 2 (ABI2), and auxin-repressed protein (ARP), in seeds pollinated with pollen from close-blocked anthers, cold-protected pollen, and pollen from freshly opened anthers. The close-blocked anther treatment led to significantly upregulated expression of IAAS, SUS, GA2ox, and ABI2, whereas ARP expression decreased markedly, indicating a propensity toward prolonged seed dormancy. Conversely, in the low-temperature-protected anther model, SUS, ARP, GA2ox, and IAAS exhibited reduced expression levels, whereas the expression of ABI2 was upregulated, overall facilitating seed germination.</jats:p>

<jats:p>Pecan (<jats:italic>Carya illinoensis</jats:italic>), an economically important deciduous tree, bears commercially valuable nutritional nuts. Spring freezes in April can severely injure pecan buds, decreasing bloom, and fruit set. This study determined how low temperatures affect pecan buds/flowers at different growth stages in several pecan scion/rootstock combinations. This study focused on three pecan scion/rootstock combinations: Pawnee/Peruque (PP), Kanza/Giles (KG), and Maramec/Colby (MC), grown at the Cimarron Valley Research Station, Perkins, Oklahoma. Branches at three different growth stages, i.e., outer bud scale shed, one week after bud break, and early bloom stages were collected from PP, MC, and KG. Branches were held in a Conviron E8 freezing unit at 4 temperatures (-2, 0, 2, and 4°C) for 4 and 8 hours; A total of 8 treatments. One sample set was kept as an untreated control. After 2–3 weeks, branch samples from all the temperature treatments were observed and categorized into two groups. Group one with number of branches had healthy buds/formation of healthy leaves/flowers and group two with number of dead branches. The carbohydrate content reserved from dormant was analyzed using an Anthrone reagent. Visual observations and carbohydrate analyses revealed differences in damage and carbohydrate content among the scion/rootstock combinations, low-temperature treatments, and growth stages. The MC combination had minimum visual damage to leaves, buds, and flowers and significantly lower soluble sugars and starch in bark phloem as well as significantly lower soluble sugars in woody tissue xylem. The KG combination had maximum visual damage and significantly higher soluble sugars and starches in the bark, and soluble sugars in the woody tissues. These results indicate the MC combination is more tolerant to spring freeze damage at all three growth stages compared to the other two pecan scion/rootstock combinations. The results also demonstrate the MC combination is using more non-structural carbohydrates, soluble sugars and starches, suggesting this is a possible mechanism in its freeze tolerance.</jats:p>

<jats:p>Invasive plants represent a significant global challenge as they compete with native plants for limited resources such as space, nutrients and pollinators. Here, we focused on four invasive species that are widely spread in the French Pyrenees, <jats:italic>Buddleja davidii</jats:italic>, <jats:italic>Reynoutria japonica</jats:italic>, <jats:italic>Spiraea japonica</jats:italic> and <jats:italic>Impatiens glandulifera</jats:italic>, and analyzed their visual advertisement signals with respect to those displayed by their surrounding native species using a perceptual approach based on the neural mechanisms of bee vision given that bees are regular pollinators of these plants. We collected 543 spectral reflections from the 4 invasive species, and 66 native species and estimated achromatic and chromatic similarities to the bee eye. <jats:italic>R. japonica, S. japonica</jats:italic> and <jats:italic>B. davidii</jats:italic> were inconspicuous against the foliage background and could be hardly discriminated in terms of color from their surrounding native plants. These characteristics promote generalization, potentially attracting pollinators foraging on similar native species. Two morphs of <jats:italic>I. glandulifera</jats:italic> were both highly salient in chromatic and achromatic terms and different from their surrounding native species. This distinctive identity facilitates detection and learning in association with rich nectar. While visual signals are not the only sensory cue accounting for invasive-plant success, our study reveals new elements for understanding biological invasion processes from the perspective of pollinator perceptual processes.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>Pear decline (PD) is one of the most devastating diseases of <jats:italic>Pyrus communis</jats:italic> in Europe and North America. It is caused by the pathogen <jats:italic>‘Candidatus</jats:italic> Phytoplasma pyri’ and transmitted by pear psyllids (<jats:italic>Cacopsylla pyri</jats:italic>, <jats:italic>C. pyricola</jats:italic>, and <jats:italic>C. pyrisuga</jats:italic>). Identifying attractant and repellent volatile organic compounds (VOCs) could improve the development of alternative plant protection measurements like push-pull or attract-and-kill strategies against pear psyllids. Our objective was to investigate which chemical cues of the host plant could influence the host-seeking behavior of pear psyllids, and if cedarwood (CWO) and cinnamon bark (CBO) essential oils could serve as repellents.</jats:p></jats:sec><jats:sec><jats:title>Results and discussion</jats:title><jats:p>Based on the literature, the five most abundant VOCs from pear plants elicited EAG responses in both <jats:italic>C. pyri</jats:italic> and <jats:italic>C. pyrisuga</jats:italic> psyllid species. In Y-olfactometer trials, single compounds were not attractive to <jats:italic>C. pyri</jats:italic>. However, the main compound mixture was attractive to <jats:italic>C. pyri</jats:italic> and <jats:italic>C. pyrisuga</jats:italic> females. CWO and CBO were repellent against <jats:italic>C. pyri</jats:italic>, and when formulated into nanofibers (NF), both were repellent in olfactometer trials. However, CBO nanoformulation was ineffective in masking the odors of pear plants. In a field trial, attractive, repellent CWO and blank formulated NF were inserted in attractive green sticky traps. <jats:italic>C. pyri</jats:italic> captures in traps with CWO NF were statistically lower than in traps with the attractive mixture. Nevertheless, no statistical differences in the numbers of caught specimens were observed between CWO NF and those captured in green traps baited with blank NF. Transparent traps captured fewer psyllids than green ones. In a second field study with a completed different design (push-and-count design), dispensers filled with CBO were distributed within the plantation, and attractive green sticky traps were placed around the plantation. The numbers of trapped pear psyllids increased significantly in the border of the treated plantation, showing that psyllids were repelled by the EOs in the plantation. Although further field evaluation is needed to assess and improve their effectiveness, our results show that these aromatic compounds, repellent or attractive both in nanoformulations and marking pen dispensers, offer great potential as an environmentally sustainable alternative to currently applied methods for managing pear decline vectors.</jats:p></jats:sec>

<jats:p><jats:italic>Fusarium</jats:italic> wilt, caused by <jats:italic>Fusarium oxysporum</jats:italic> f. sp. <jats:italic>cubense</jats:italic> Tropical Race 4 (<jats:italic>Foc</jats:italic> TR4), poses a significant threat to banana production globally, thereby necessitating effective biocontrol methods to manage this devastating disease. This study investigates the potential of <jats:italic>Bacillus siamensis</jats:italic> strain JSZ06, isolated from smooth vetch, as a biocontrol agent against <jats:italic>Foc</jats:italic> TR4. To this end, we conducted a series of <jats:italic>in vitro</jats:italic> and <jats:italic>in vivo</jats:italic> experiments to evaluate the antifungal activity of strain JSZ06 and its crude extracts. Additionally, genomic analyses were performed to identify antibiotic synthesis genes, while metabolomic profiling was conducted to characterize bioactive compounds. The results demonstrated that strain JSZ06 exhibited strong inhibitory activity against <jats:italic>Foc</jats:italic> TR4, significantly reducing mycelial growth and spore germination. Moreover, scanning and transmission electron microscopy revealed substantial ultrastructural damage to <jats:italic>Foc</jats:italic> TR4 mycelia treated with JSZ06 extracts. Genomic analysis identified several antibiotic synthesis genes, and metabolomic profiling revealed numerous antifungal metabolites. Furthermore, in pot trials, the application of JSZ06 fermentation broth significantly enhanced banana plant growth and reduced disease severity, achieving biocontrol efficiencies of 76.71% and 79.25% for leaves and pseudostems, respectively. In conclusion, <jats:italic>Bacillus siamensis</jats:italic> JSZ06 is a promising biocontrol agent against <jats:italic>Fusarium</jats:italic> wilt in bananas, with its dual action of direct antifungal activity and plant growth promotion underscoring its potential for integrated disease management strategies.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>Ferns constitute the second largest group of vascular plants. Previous studies have shown that the diversity and composition of fern communities are influenced by resource availability and water stress, among other factors. However, little is known about the influence of these environmental factors on their biotic interactions, especially regarding the relationship between mycorrhizal fungi and ferns. The present study compares the mycorrhizal communities associated with 36 populations of Struthiopteris spicant L. Weiss across Europe and North America. This species exhibits a great tolerance to variations in light, nutrient, and pH conditions, and it can survive with and without mycorrhizae.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>With the aim of determining which environmental factors impact the composition and abundance of the root-associated fungal communities in this species, we used an ITS-focused metabarcoding approach to identify the mycorrhizal fungi present and analyzed the influence of climatic and edaphic variables at global and regional scales</jats:p></jats:sec><jats:sec><jats:title>Results and discussion</jats:title><jats:p>We encountered striking differences in the relative abundance of arbuscular mycorrhizal fungi (AMF) between S. spicant populations at both spatial levels. We recorded a total of 902 fungal ASVs, but only 2– 4% of the total fungal diversity was observed in each individual, revealing that each fern had a unique fungal community. Light availability and the interactive action of pH and soil nitrogen concentration showed a positive influence on AMF relative abundance, explaining 89% of the variance. However, environmental factors could only explain 4– 8% of the variability in AMF community composition, indicating that it might be determined by stochastic processes. These results support the hypothesis that ferns may be more independent of mycorrhization than other plant groups and interact with fungi in a more opportunistic manner.</jats:p></jats:sec>

<jats:p><jats:italic>Paraburkholderia ultramafica</jats:italic> STM10279<jats:sup>T</jats:sup> is a metal-tolerant rhizobacterium that promotes plant growth. It was isolated from the roots of <jats:italic>Tetraria arundinaceae</jats:italic>, a pioneer endemic tropical herb growing on ultramafic soils in New Caledonia. We have recently shown that the main mechanism of metal tolerance of <jats:italic>P. ultramafica</jats:italic> is related to the production of an acidic exopolysaccharide (EPS). To explore the potential role of this EPS in the plant’s environmental adaptation, we first elucidated its structure by employing a combination of chromatography and mass spectrometry techniques. These analyses revealed that the EPS is highly branched and composed of galactosyl (35.8%), glucosyl (33.2%), rhamnosyl (19.5%), mannosyl (7.2%), and glucuronosyl residues (4.4%), similar to the EPS of the <jats:italic>Burkholderia cepacia</jats:italic> complex known as cepacian. We subsequently conducted greenhouse experiments on <jats:italic>Tetraria comosa</jats:italic> plantlets inoculated with <jats:italic>P. ultramafica</jats:italic> or a solution of its EPS during transplanting onto ultramafic substrate. The data showed that the dry weight of <jats:italic>T. comosa</jats:italic> shoots was 2.5 times higher in the plants treated with the EPS compared to the unexposed plants. In addition, inductively coupled plasma–optical emission spectrometry (ICP-OES) analysis revealed that exposure to the EPS significantly increased Ca, Mg, K, and P uptake as well as K content in roots. <jats:italic>In vitro</jats:italic> experiments using the Pikovskaya method showed that the EPS was able to solubilize phosphorus. Consistent with the retention of metals in roots and a reduction in shoots, our data revealed a significant decrease in metal translocation factors (TFs) in the plants inoculated with the EPS. These results suggest a beneficial effect of the rhizobacterial EPS on plant growth and abiotic stress mitigation. In addition, the data suggest that the reduced levels of trace metals in plants exposed to <jats:italic>P. ultramafica</jats:italic> STM10279<jats:sup>T</jats:sup> are due to metal chelation by the EPS. Further investigations are needed to firmly demonstrate whether this EPS could be used as a biostimulant for plant growth and adaptation to ultramafic soils.</jats:p>