Plants perceive light signals through photoreceptors such as CRY1 to regulate growth and development. It is well-known that Arabidopsis CRY1 is a nucleocytoplasmic protein that mediates light inhibition of hypocotyl elongation in the nucleus, but the mechanisms by which CRY1 regulates root growth and functions in the cytoplasm remain poorly understood. Here, we identified eIF3G1, a subunit of the eukaryotic translation initiation factor 3 (eIF3) complex, as a CRY1-interacting protein associated with light-regulated root development. Under blue light, eif3g1 mutants showed longer primary roots, whereas eIF3G1 overexpression reduced root elongation, accompanied by corresponding changes in root apical meristem size. Differential irradiation experiments indicated that shoot illumination is required for eIF3G1-dependent root phenotypes. Transcriptome analysis revealed changes in translation-related and light-responsive genes in response to eIF3G1 perturbation. Comparison with the cry1 transcriptome revealed overlapping differentially expressed genes, including BIC1 and BIC2, and the bic1 bic2 double mutant showed reduced root elongation. Together, these findings identify eIF3G1 as a CRY1-interacting factor that contributes to the shoot-dependent regulation of root growth under blue light, suggesting that eIF3G1 may be associated with the CRY1-dependent shoot-to-root regulation of root growth.

Lymantria xylina is the most important defoliator, damaging the effective coastal windbreak tree species Casuarina equisetifolia. However, the underlying genetic mechanisms through which C. equisetifolia responds to L. xylina attacks remain unknown. Here, we compared the transcriptional, phytohormone and metabolic differences between susceptible (S) and resistant (R) C. equisetifolia cultivars in response to L. xylina feeding. The main L. xylina-induced resistance in C. equisetifolia was a jasmonate (JA) response and JA synthesis was highly induced by L. xylina feeding at both the transcriptional and metabolic levels, thus promoting flavonoid accumulation. The JA response was highly activated by L. xylina feeding on the R but not in the S cultivar, although the JA signalling pathway was intact in both cultivars. We found a single amino acid mutation in the homologues of glutamate receptor-like protein 3.6 (CeGLR3.6T807I) in the S cultivar. Compared with the GLR3.6 homologues in the R cultivar, phosphorylation of CeGLR3.6T807I was not induced by insect feeding, leading to a decreased JA response in the S cultivar. Collectively, this study provides new insights into the function of CeGLR3.6 in regulating the JA response of C. equisetifolia to L. xylina feeding.

Phosphorus (P) deficiency is critical to the renewal barrier of she-oak (Casuarina equisetifolia), an important tree species used for coastal protection. However, the response of she-oak to P deficiency remains unclear. In this study, we compared the phenotypes of two she-oak cultivars, the P deficiency-sensitive 'Chihu219' and the insensitive 'Chihu397', and found that P deficiency significantly increased root growth, P concentration and phosphorus absorption efficiency (PAE) in Chihu219, but not in Chihu397. We also analyzed the transcriptome and metabolome of these cultivars under different P conditions and showed that trans-zeatin riboside (tZR) levels were highly suppressed by P deficiency in Chihu219, but not in Chihu397. Furthermore, exogenous tZR suppressed both root P concentration and PAE while promoting P-use efficiency. We also identified CeIPT5 (isopentenyltransferase 5) as a key regulatory gene of tZR biosynthesis and found that its expression was more highly induced by P deficiency in Chihu219 than in Chihu397. We also showed that overexpression of CeIPT5 in insensitive she-oak lines reduced tZR concentration and increased root P concentration compared with the vector control. Taken together, P deficiency can greatly reduce tZR accumulation in P deficiency-insensitive she-oak at least by activating the tZR accumulation regulatory gene, CeIPT5, thereby promoting root elongation and P concentration. This study not only provides a genetic basis for enhancing PAE in woody plants but also establishes a theoretical basis for optimizing root structure and improving nutrient utilization efficiency, thereby promoting sustainable forestry development.

ABSTRACT Beauveria bassiana ( Bb ) is one of the most widely used biocontrol agents, and its products constitute more than one-third of the global market share of fungal insecticides. Solid-state fermentation (SSF) is widely used in the production of Beauveria bassiana ( Bb ) because of its economic practicality and high production efficiency. However, the heat generated during fermentation can sharply reduce both the yield and quality of Bb , and current industrial methods to mitigate high temperatures during fermentation are inadequate, leading to increased production costs. Thus, exploring the underlying mechanism of how heat is produced by Bb is crucial for improving the SSF procedure and yield. This study employed multiomics data analysis of Bb during SSF to explore the relationships between fungal fermentation and environmental factors. We found that the heat production period for SSF was 12 hours to 48 hours post-inoculation. To further explore the underlying mechanism during this heating period, we identified 454 temperature-correlated metabolites (TCMs) and 1,994 temperature-correlated genes (TCGs). Annotations of the above TCMs and TCGs revealed significant enrichment in the arginine biosynthesis pathway; specifically, the expression level of glutamine synthetase, a TCG, decreased with fermentation time, whereas the expression levels of the TCGs L-arginine and L–glutamine increased with fermentation time, and glutamine synthetase and L-glutamine in the arginine biosynthesis pathway cycle produced the end product L-arginine. Furthermore, when the substrates of the SSF were treated with exogenous arginine, the temperature peak of the SSF significantly decreased with increasing concentration of exogenously added arginine. IMPORTANCE A large amount of experimental evidence from the field has shown that Bb is an irreplaceable mature product that protects the health of our agriculture and ecosystem. In addition to high efficiency and host extensiveness, low cost is a critical merit that makes Bb products frequently used in the field. However, the growing cost of power and labor in the Bb industry, especially the SSF procedure, has significantly increased the price of its products, thus restricting the use of Bb in the field. This study not only fills the theoretical knowledge gaps concerning the molecular basis of the interrelationship between Bb and the fermentation environment during SSF but also provides an economical and applicable strategy (the addition of arginine to the fermentation media) to further lower the cost and increase the yield of Bb during SSF at the industrial level.

BACKGROUNDCasuarina equisetifolia, a crucial species of coastal windbreaks, is highly susceptible to infestation by Anoplophora chinensis. This stem-boring pest poses a significant threat to the health and sustainability of Casuarina equisetifolia forests. Understanding the molecular mechanisms underlying the host preference of A. chinensis to Casuarina equisetifolia is essential for developing effective pest management strategies.RESULTSThrough field surveys, we identified two cultivars of Casuarina equisetifolia that exhibited differing levels of host preference for A. chinensis. Further analysis of multi-omics data (phenomics, transcriptomics, and metabolomics) from these cultivars revealed that longifolene plays a significant role in attracting A. chinensis to Casuarina equisetifolia. Additionally, the jasmonic acid (JA) signaling pathway was found to suppress longifolene accumulation, primarily through the interaction between the jasmonate ZIM-domain (JAZ) proteins and the terpene synthase (TPS) gene. Moreover, we identified a critical JAZ component, CeJAZ3, whose overexpression led to the down-regulation of TPS expression levels and, consequently, a reduced release of longifolene.CONCLUSIONWe confirmed that the negative regulator of host preference, CeJAZ3, in the JA signaling pathway can suppress the expression of TPSs, thereby down-regulating the accumulation of longifolene in Casuarina equisetifolia and indirectly suppressing the attraction of host plants to A. chinensis, which provides a basis for the integrated management of A. chinensis. (c) 2024 Society of Chemical Industry.

Pine wilt disease (PWD), transmitted by Monochamus alternatus (JPS), poses a severe threat to global pine forests. Although the entomopathogenic fungi Beauveria bassiana (Bb) and Metarhizium anisopliae (Ma) represent environmentally friendly biocontrol alternatives, their practical application is limited by inconsistent field performance and an incomplete understanding of host–pathogen interactions. We employed dual RNA-seq at the critical 48 h infection time point to systematically compare the transcriptional responses between JPS and Bb/Ma during infection. Key findings revealed distinct infection strategies: Bb preferentially induced autophagy pathways and modulated host carbohydrate metabolism to facilitate nutrient acquisition, triggering corresponding tissue degradation responses in JPS. In contrast, Ma primarily co-opted host amino acid and sugar metabolic pathways for biosynthetic processes, eliciting a stronger immune defense activation in JPS. Notably, the mTOR signaling pathway was identified as a key regulator of the differential host responses to various entomopathogenic fungi. Further functional validation-specifically, the application of a chemical inhibitor and RNAi targeting mTOR in JPS-confirmed that mTOR inhibition selectively enhanced Bb-induced mortality in JPS without affecting Ma virulence. Our findings reveal the molecular determinants of host–pathogen specificity in PWD biological control and indicate that mTOR regulation could serve as an effective strategy to improve fungal pesticide performance.

Lymantria xylina is the most important defoliator, damaging the effective coastal windbreak tree species Casuarina equisetifolia . However, the underlying genetic mechanisms through which C . equisetifolia responds to L . xylina attacks remain unknown. Here, we compared the transcriptional, phytohormone and metabolic differences between susceptible (S) and resistant (R) C . equisetifolia cultivars in response to L . xylina feeding. The main L . xylina -induced resistance in C . equisetifolia was a jasmonate (JA) response and JA synthesis was highly induced by L . xylina feeding at both the transcriptional and metabolic levels, thus promoting flavonoid accumulation. The JA response was highly activated by L . xylina feeding on the R but not in the S cultivar, although the JA signalling pathway was intact in both cultivars. We found a single amino acid mutation in the homologues of glutamate receptor-like protein 3.6 (CeGLR3.6 T807I ) in the S cultivar. Compared with the GLR3.6 homologues in the R cultivar, phosphorylation of CeGLR3.6 T807I was not induced by insect feeding, leading to a decreased JA response in the S cultivar. Collectively, this study provides new insights into the function of CeGLR3.6 in regulating the JA response of C . equisetifolia to L . xylina feeding.

Arhopalus unicolor is a carrier of the pine wood nematode (PWN), which causes pine wilt disease, killing pine trees and causing considerable economic and environmental losses. While the A. unicolor mitochondrial genome has been published, a high-quality genome assembly and annotation of A. unicolor is not yet available. To address this, we assembled a chromosome-level reference genome assembly of A. unicolor with a combination of Illumina, PacBio, and Hi-C sequencing technologies. The final genome size was determined to be 1268.11 Mb, with a GC% of 32.44%, and the scaffold N50 value was 19.30 Mb. A total of 98.77% of the assembled sequences mapped to 10 pseudochromosomes, and BUSCO analysis revealed high completeness, with 97.15% gene coverage. Furthermore, the genome contains 71.74% repeat elements and encompasses 16,450 predicted protein-coding genes. This genome sequence of A. unicolor will be a valuable resource for understanding the genetics and evolutionary history of this species and for developing effective management strategies for this PWN carrier.

BACKGROUND:Pine wood nematode (PWN; Bursaphelenchus xylophilus) is the causative agent of pine wilt disease (PWD), which is considered the most dangerous biohazard to conifer trees globally. The transmission of PWN relies on insect vectors, particularly the Japanese pine sawyer (JPS; Monochamus alternatus). However, the molecular mechanism underlying PWN-JPS assembly remains largely unknown. RESULTS:Here, we found that both geographical and gender could significantly affect the PCA (PWN carrying amount) of JPS; thus, JPS transcriptomes from diverse locations and genders were explored regard to PWN loading. Due to the shortage of genomes, we developed a full-length reference transcriptome for analyzing next-generation sequencing data. A comparative genomic study was performed, and 11 248 potential PWN-carrying associate genes (β) were nominated in JPS by using the reported genomes of PWN and non-PWN carrier insect species. Then, 151 differentially expressed transcripts (DETs), 28 of them overlapped with β, correlated with the PCA of JPS were nominated by RNA-Seq, and found that fatty acid β-oxidation might be the key factor that affected the PCA of JPS. Furthermore, JPS fatty acid β-oxidation rates were experimentally decreased using the inhibitor Etomoxir, leading to an increased PCA of JPS. Meanwhile, silencing MaCPT1 in JPS by RNA interference led to a decreased fatty acid β-oxidation rate and increased PCA of JPS. CONCLUSIONS:In conclusion, MaCPT1 was able to decrease the PWN-JPS assembly formation through the fatty acid β-oxidation of JPS. These results provide new insights for exploring the impact of PWN invasion on JPS. © 2024 Society of Chemical Industry.

Plant undergo juvenile-to-adult transition to become competent for age-dependent floral induction and reproductive transition, which is of great significance for improving the seed quality and maintaining desirable genetic traits of Chinese fir, but the underlying molecular mechanize still remains unknown. Here, we investigated the function of our newly identified spermatophyte specific transcriptional co-activator TAC3 (Transcriptional Activator in Chinese fir 3) and its homologues (TAL1) in the model plant Arabidopsis. Both TAC3 and TAL1 can negatively regulate flowering, and activate miR156 expression to delay the phase transition. Moreover, we found that HDA9 and its its homologues in Chinese fir, ClHDA9, can directly binding to the promoter region of MIR156A and ClMIR156A, respectively. Directly interaction with ClHDA9 and HDA9 are necessary for the transcriptional activation of TAC3 and TAL1 on miR156, respectively. TAC3 and TAL1 also involve in the chromatin remodeling, shown as up-regulated H3K27ac level within the promoter region of ClMIR156A and MIR156A. Together, this work shows that TAC3 and its homologues are a new group of transcriptional co-activator that involving in aging-dependent flowering signal pathway of both angiosperms and gymnosperms.### Competing Interest StatementThe authors have declared no competing interest.

Pine wilt disease (PWD), caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus , results in significant economic and ecological damage to Pinus forests and plantations worldwide. Pinus massoniana is the primary host of PWD in southern China, but its response to the PWN remains largely unstudied. Previously, we observed PWD in a P. massoniana nursery that contained over 71 commonly used cultivars. Through field phenotyping, we identified two groups of PWN resistant cultivars. Resistant cultivars (RC) exhibited very low PWN carrying amounts (PCA) and had relatively low mortality, and tolerant cultivars (TC) had high PCA but low mortality. In this study, we confirmed via PWN inoculation assays that the resistant and tolerant cultivars had lower mortality rates, 10% and 11%, respectively, than other cultivars (which had a mortality rate of 83.3%). The RC had a PCA that was significantly lower than that of other cultivars, while the TC exhibited a higher PCA. To explore the molecular mechanisms underlying the response of P. massoniana to PWN, the transcriptome and metabolome of the above cultivars were profiled by high throughput sequencing. As no reference genome is available for P. massoniana , we generated a new full-length transcriptome library with iso-seq. Using the transcriptome and metabolome from different P. massoniana cultivars inoculated with PWN, we found three major PWD resistance strategies. 1) The common response strategy involved three important molecular pathways. First, synthesis of indole-3-acetic acid (IAA) and abcisic acid (ABA) were suppressed during PWN invasion, thus suppressing the synthesis of polysaccharides (especially myo-inositol and trehalose) and (-)-riboflavin through ABC transporters. Second, by inhibiting aspartic acid, the synthesis of arginine and proline through APS5 (aspartate aminotransferase 5) were suppressed. Third, by reducing cysteine, GERD (germacrene D synthase) was up-regulated, and sesquiterpenoid and triterpenoid metabolites were accumulated to resist PWN invasion. 2) The most effective resistance strategy involved the accumulation of reactive oxygen species (ROS), which enhanced jasmonic acid (JA) accumulation and highly induced the expression of chitinase, thus improving resistance to PWN. 3) The tolerance strategy involved the induction of phosphatidylcholine, which promoted flavonoid and anthocyanin synthesis via LPIN (phosphatidate phosphatase), LOX2S (lipoxygenase), and LOX1_5 (linoleate 9S-lipoxygenase), thus significantly inhibiting the pathogenicity of the PWN but not the PCA. These results illustrate the molecular mechanisms by which P. massoniana cultivars resist or tolerate PWN and are of great significance in the prevention and control of PWD.### Competing Interest StatementThe authors have declared no competing interest.

Long-term monocultures of tea and the excessive use of chemical fertilizer lead to the degradation of soil quality. Improving the soil quality of ex-tea plantations through vegetation restoration is an important task. However, the changes in soil nutrients, fungal communities, and the effects of microorganisms on soil nutrients after reforestation remain unclear. Therefore, in this study, we aimed to explore the effects of Pinus and Chinese fir on soil nutrients and fungal communities in ex-tea plantation areas that were subjected to the reforestation modes of pure forest and mixed forest by measuring soil chemical properties and ITS rRNA gene sequences. The results showed that (1) after reforestation, the relative normalized difference vegetation index (NDVI) of the Mixed forest, Mixed Pine and Mixed Fir areas increased (p < 0.05) compared to that of pure forest; (2) the soil organic carbon (SOC), total nitrogen (TN), and N:P ratios of the mixed forest increased by an average of 54%, 90%, and 299% (p < 0.05) compared to pure forest, whereas the total phosphorus (TP) and available potassium (AK) decreased by an average of 39% and 89% (p < 0.05); and (3) there was no significant difference in the diversity of the fungal communities of the pure and mixed forests, but the fungal phyla Mucoromycota, Glomeromycota, and Rozellomycota were significantly different in the pure and mixed forests. This differing microbial composition led to a significant increase (p < 0.05) in symbiotrophs (ecotomycorhizal, ericoid mycorhizal) in the mixed forest, which was negatively correlated with the soil TP and positively correlated with the TN and the N:P ratio. In addition, there was also a significant decrease (p < 0.05) in complex nutrient types (ectomycorrhizal-fungal parasite-plant saprotroph-wood saprotroph), which were negatively correlated with the SOC and TN, and arbuscular mycorrhizas, which were positively correlated with the TP. Our results show that the chemical properties of soils and the structure of the fungal communities changed significantly due to the reforestation of Chinese fir and Pinus, and the mixed forest mode of reforestation was more conducive to improving the soil quality; therefore, a mixed forest of Chinese fir and Pinus can be used to improve degraded soils in ex-tea planting areas.

Cryptochromes (CRYs) are blue light receptors that mediate plant photoresponses through regulating gene expressions. We recently reported that Arabidopsis CRY2 could form light-elicited liquid condensates to control RNA methylation. However, whether CRY2 condensation is involved in other gene expression–regulatory processes remains unclear. Here, we show that MOS4-associated complex subunits 3A and 3B (MAC3A/3B) are CRY-interacting proteins and assembled into nuclear CRY condensates. mac3a3b double mutants exhibit hypersensitive photoinhibition of hypocotyl elongation, suggesting that MAC3A/3B positively control hypocotyl growth. We demonstrate the noncanonical activity of MAC3A as a DNA binding protein that modulates transcription. Genome-wide mapping of MAC3A-binding sites reveals that blue light enhances the association of MAC3A with its DNA targets, which requires CRYs. Further evidence indicates that MAC3A and ELONGATED HYPOCOTYL 5 (HY5) occupy overlapping genomic regions and compete for the same targets. These results argue that photocondensation of CRYs fine-tunes light-responsive hypocotyl growth by balancing the opposed effects of HY5 and MAC3A.

IntroductionPine wilt disease (PWD) is responsible for extensive economic and ecological damage to Pinus spp. forests and plantations worldwide. PWD is caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus) and transmitted into pine trees by a vector insect, the Japanese pine sawyer (JPS, Monochamus alternatus). Host infection by PWN will attract JPS to spawn, which leads to the co-existence of PWN and JPS within the host tree, an essential precondition for PWD outbreaks. Through the action of their metabolites, microbes can manipulate the co-existence of PWN and JPS, but our understanding on how key microorganisms engage in this process remains limited, which severely hinders the exploration and utilization of promising microbial resources in the prevention and control of PWD.MethodsIn this study we investigated how the PWN-associated fungus Aspergillus promotes the co-existence of PWN and JPS in the host trees (Pinus massoniana) via its secondary metabolite, sterigmatocystin (ST), by taking a multi-omics approach (phenomics, transcriptomics, microbiome, and metabolomics).ResultsWe found that Aspergillus was able to promote PWN invasion and pathogenicity by increasing ST biosynthesis in the host plant, mainly by suppressing the accumulation of ROS (reactive oxygen species) in plant tissues that could counter PWN. Further, ST accumulation triggered the biosynthesis of VOC (volatile organic compounds) that attracts JPS and drives the coexistence of PWN and JPS in the host plant, thereby encouraging the local transmission of PWD. Meanwhile, we show that application of an Aspergillus inhibitor (chiricanine A treatment) results in the absence of Aspergillus and decreases the in vivo ST amount, thereby sharply restricting the PWN development in host. This further proved that Aspergillus is vital and sufficient for promoting PWD transmission.DiscussionAltogether, these results document, for the first time, how the function of Aspergillus and its metabolite ST is involved in the entire PWD transmission chain, in addition to providing a novel and long-term effective nematicide for better PWD control in the field.

DNA methylation, an epigenetic mark, is proposed to regulate plant anthocyanin biosynthesis. It well known that light induces anthocyanin accumulation, with bagging treatments commonly used to investigate light-controlled anthocyanin biosynthesis. We studied the DNA methylome landscape during pear skin coloration under various conditions (fruits re-exposed to sunlight after bag removal). The DNA methylation level in gene body/TE and its flanking sequence was generally similar between debagged and bagged treatments, however differentially methylated regions (DMRs) were re-modelled after light-exposure. Both DNA demethylase homologs and the RNA-directed DNA methylation (RdDM) pathways contributed to this re-distribution. A total of 310 DEGs were DMR-associated during light-induced anthocyanin biosynthesis between debagged and bagged treatments. The hypomethylated mCHH context was seen within the promoter of PyUFGT, together with other anthocyanin biosynthesis genes (PyPAL, PyDFR and PyANS). This enhanced transcriptional activation and promoted anthocyanin accumulation after light re-exposure. Unlike previous reports on bud sports, we did not detect DMRs within the MYB10 promoter. Instead, we observed the genome-wide re-distribution of methylation patterns, suggesting different mechanisms underlying methylation patterns of differentially accumulated anthocyanins caused by either bud mutation or environment change. We investigate the dynamic landscape of genome-scale DNA methylation, which is the combined effect of DNA demethylation and RdDM pathway, in the process of light-induced fruit colour formation in pear. This process is regulated by methylation changes on promoter regions of several DEGs. These results provide a DMR-associated DEGs set and new insight into the mechanism of DNA methylation involved in light-induced anthocyanin biosynthesis.

Aims Endophyte is a new microbial resource, which has a complex micro-ecological relationship with plants. In this paper, the antagonistic effect of endophytic fungi on the growth of salt-tolerant plants was confirmed by adding endophytic fungi to the plants and testing the physiological characteristics and biomass of the seedlings.Methods Two salt-tolerant endophytic fungi Botryosphaeria Z1（T3）, Hypoxylon Y6（T4）, and their mixture（T2） were cultured in solid fermentation and added to potted soil planted with seedlings of Casuarina equisetifolia at different salinity（mass fraction: 0, 3‰, 6‰ and 9‰）, which were treated with an added fungal of seedlings.The addition of microbiological medium（T1） and no added microbiological medium（CK） were treated as two experimental controls, which was to confirm the effect of the fungal, but not the microbiological medium.Samples were taken at 15 day intervals, four times, for a total of 60 days, and the relative electronic conductivity（REC）, malondialdehyde（MDA）, soluble sugar（SS）, soluble protein（SP）, proline（PRO）, superoxide dismutase（SOD）, peroxidase（POD）, catalase（CAT）, reactive oxygen（H 2 O 2 ） of leavesand the biomass of seedling were determined each time.Important findings We found that the biomass of seedlings treated by fungal strain was significantly increased under salt stress, and the physiological characteristics were significantly affected by soil salinity, time and fungal species. At 3‰ salinity, the content of SS and SP, and the activity of SOD and CAT were higher in T2 treatment than in CK and T1 after 15 days of treatment, but the REC was significantly lower in T2, T3 and T4 treatments during the stress period. At 9‰ salinity, T2 treatment significantly reduced the REC and the content of H 2 O 2 and MDA, but significantly increased the content of SS and the activity of SOD and CAT. Especially, SP content and POD activity were also significantly increased in T2 treatment after 60 days. A stepwise regression was used to model the relationship between physiological characteristics and biomass of seedlings treated with the strains, and the path analysis showed that REC, POD and SS were the main physiological factors affecting biomass. In conclusion, the effects of different fungus on the content of osmoregulatory substances, oxidase activity and biomass of seedlings were different, and the antagonistic effect of the mixed fungus was the most obviously. Thus, the relationship between osmotic regulatory substances, antioxidant enzymes, biomass and endophytic fungi of Casuarina equisetifolia under salt stress was clarified, which provided a basic for the further study on the stress resistant engineering fungi for Casuarina equisetifolia.

AbstractBACKGROUNDPine wilt disease (PWD) is responsible for extensive economic and ecological damage toPinusspp. forests and plantations worldwide. PWD is caused by the pine wood nematode (PWN,Bursaphelenchus xylophilus) and transmitted into pine trees by a vector insect, the Japanese pine sawyer (JPS,Monochamus alternatus). Host infection by PWN will attract JPS to spawn, which leads to the co-existence of PWN and JPS within the host tree, an essential precondition for PWD outbreaks. Through the action of their metabolites, microbes can manipulate the co-existence of PWN and JPS, but our understanding on how key microorganisms engage in this process remains limited, which severely hinders the exploration and utilization of promising microbial resources in the prevention and control of PWD.RESULTSIn this study we investigated how the PWN-associated fungusAspergilluspromotes the co-existence of PWN and JPS in the host trees (Pinus massoniana) via its secondary metabolite, sterigmatocystin (ST), by taking a multi-omics approach (phenomics, transcriptomics, microbiome, and metabolomics). We found thatAspergilluswas able to promote PWN invasion and pathogenicity by increasing ST biosynthesis in the host plant, mainly by suppressing the accumulation of ROS (reactive oxygen species) in plant tissues that could counter PWN. Further, ST accumulation triggered the biosynthesis of VOC (volatile organic compounds) that attracts JPS and drives the coexistence of PWN and JPS in the host plant, thereby encouraging the local transmission of PWD. Meanwhile, we show that application of anAspergillusinhibitor (chiricanine A treatment) results in the absence ofAspergillusand decreases thein vivoST amount, thereby sharply restricting the PWN development in host. This further proved thatAspergillusis vital and sufficient for promoting PWD transmission.CONCLUSIONSAltogether, these results document, for the first time, how the function ofAspergillusand its metabolite ST is involved in the entire PWD transmission chain, in addition to providing a novel and long-term effective nematicide for better PWD control in the field.

Flooding is one of the main abiotic stresses suffered by plants. Plants respond to flooding stress through regulating their morphological structure, endogenous hormone biosynthesis, and genetic signaling transduction. We previously found that Fokienia hodginsii varieties originating from Gutian exhibited typical flooding tolerance traits compared to three other provenances (Yongzhou, Sanming, Nanping), expressed as increased height, longer diameter at breast height (DBH), and smaller branch angle. Herein, the changes in endogenous gibberellins (GA) and abscisic acid (ABA) contents were measured under flooding stress in F. hodginsii, and ABA was found to decrease, whereas GA increased with time. Furthermore, the GA and ABA contents of the varieties originating from Gutian and the three other provenances were measured, and the results indicated that F. hodginsii from Gutian could respond more rapidly to flooding stress. The transcriptomes of the varieties originating from Gutian and the other three provenances were compared using RNA sequencing to explore the underlying genetic mechanisms of the flood-resistant phenotypes in F. hodginsii. The results indicated that two flood-stress response genes (TRINITY_DN142_c0_g2 and TRINITY_DN7657_c0_g1) were highly related to both the ABA and GA response in F. hodginsii.

Background Development of Pantana phyllostachysae , a moso bamboo pest, is affected by its diet. Understanding the mechanism underlying the different insect-resistant capacities of on- and off-year moso bamboo fed by P. phyllostachysae is crucial for managing pest outbreaks. As microbes were proven to influence plant immunity, we compared gut microbial communities of P. phyllostachysae with different diets by metabarcoding sequencing. By using sterilization assay, microbes were removed from leaf surfaces, and thus we confirmed that microbes inhabiting moso bamboo leaves impact the weight of P. phyllostachysae larva. Furthermore, the gut microbial communities of P. phyllostachysae fed on on- and off-year bamboo leaves were compared, to identify the functional microbial communities that impact the interaction between bamboo leaves and P. phyllostachysae . Results We found that species from orders Lactobacillales and Rickettsiales are most effective within functional microbiota. Functional prediction revealed that gut microbes of larva fed on on-year leaves were related to naphthalene degradation, while those fed on off-year leaves were related to biosynthesis of ansamycins, polyketide sugar unit biosynthesis, metabolism of xenobiotics, and tetracycline biosynthesis. Most functional microbes are beneficial to the development of larva that feed on on-year bamboo leaves, but damage the balance of intestinal microenvironment and immune systems of those larva that feed on off-year leaves. Conclusions This work developed an efficient strategy for microbiome research of Lepidopteran insects and provided insights into microbiota related to the interaction between host plants and P. phyllostachysae . We provided microbial candidates for the ecological control of P. phyllostachysae according to the function of effective microbiota.