The rhizosphere and root selections intensify fungi-bacteria interaction in abiotic stress-resistant plants.

The microbial communities, inhabiting around and in plant roots, are largely influenced by the compartment effect, and in turn, promote the growth and stress resistance of the plant. However, how soil microbes are selected to the rhizosphere, and further into the roots is still not well understood. Here, we profiled the fungal, bacterial communities and their interactions in the bulk soils, rhizosphere soils and roots of eleven stress-resistant plant species after six months of growth. The results showed that the root selection (from the rhizosphere soils to the roots) was stronger than the rhizosphere selection (from the bulk soils to the rhizosphere soils) in: (1) filtering stricter on the fungal (28.5% to 40.1%) and bacterial (48.9% to 68.1%) amplicon sequence variants (ASVs), (2) depleting more shared fungal (290 to 56) and bacterial (691 to 2) ASVs measured by relative abundance, and (3) increasing the significant fungi-bacteria crosskingdom correlations (142 to 110). In addition, the root selection, but not the rhizosphere selection, significantly increased the fungi to bacteria ratios (f:b) of the observed species and shannon diversity index, indicating unbalanced effects to the fungal and bacteria communities exerted by the root selection. Based on the results of network analysis, the unbalanced root selection effects were associated with increased numbers of negative interaction (140 to 99) and crosskingdom interaction (123 to 92), suggesting the root selection intensifies the negative fungi-bacteria interactions in the roots. Our findings provide insights into the complexity of crosskingdom interactions and improve the understanding of microbiome assembly in the rhizosphere and roots.

Fluorene-9-bisphenol exposure damages the testis in mice through a novel mechanism of ferroptosis.

Fluorene-9-bisphenol (BHPF) is an emerging global endocrine-disrupting chemical found in numerous household products as a substitute of bisphenol A. Many studies have reported various toxicities associated with BHPF. However, the effect of BHPF on male reproduction, particularly on the structural integrity of the blood testis barrier (BTB) in mice, has not yet been extensively studied. Ferroptosis, a newly identified form of cell death, occurs in the testicular tissue following exposure to BPA, affecting male fertility. We investigated whether ferroptosis plays a role in BHPF-induced testicular damage. The findings indicated that BHPF exposure led decreases in serum testosterone (T) concentration and sperm concentration and motility in mice. Furthermore, BHPF disrupted the BTB by interfering with key BTB-related proteins, including Cx43, ß-catenin, and ZO-1. Moreover, BHPF induced ferroptosis through the induction of lipid peroxidation, iron overload, oxidative stress, and mitochondrial dysfunction in the testicular tissue. Inhibition of ferroptosis using Fer-1 mitigated the BHPF-induced damage to the BTB and ferroptosis in TM4 cells. Overall, our findings indicated the detrimental effects of BHPF on male reproductive function in mice, suggesting ferroptosis as a mechanism underlying testicular damage.

Comparative Study of the Co-Occurring Alternaria and Colletotrichum Species in the Production of Citrus Leaf Spot.

Both of the two citrus diseases, Alternaria brown spot (ABS) and Anthracnose, caused by Alternaria and Colletotrichum spp., respectively, can produce leaf lesions which are hard to differentiate. These two diseases have been confused as causal agents of brown spot for over a decade in China. In this study, citrus leaves with or without brown spot were collected from Zhaoqing, Guangdong and Wanzhou, Chongqing, and were further used for the taxonomic and functional comparisons between the co-occurring Alternaria and Colletotrichum species. In the amplicon sequencing, the average relative abundance and the composition of Alternaria, but not Colletotrichum, increased (from 0.1 to 9.9, p = 0.059; and to 0.7, p < 0.05) and significantly altered (p < 0.01) with the brown spot in Zhaoqing and Wanzhou, respectively. Two representative isolates Alternaria sp. F12A and Colletotrichum sp. F12C, from the same brown spot, were proved with different virulence and host response activation to citrus leaves. F12A caused typical symptoms of brown spot with the average spot length expanded to 5 and 6.1 cm, and also altered the citrus global gene expression 48 and 72 h after inoculation. In addition, F12A enriched the expression of genes that were most frequently involved in plant defense. In comparison, F12C caused leaf spot limited to the wounded site, and its milder activation of host response recovered 72 h after inoculation. Our study indicates that the incidence of brown spot in China is caused by Alternaria species, and the ABS should be a fungal disease of major concern on citrus.

First Report of Dieback Caused by Lasiodiplodia pseudotheobromae on Ormosia pinnata in China.

Ormosia pinnata (Lour.) Merr. is an important tree used for landscape and plant recovery of barren slopes in China. During an investigation of plant disease on landscape trees in 2018, a dieback was observed on O. pinnata trees in Guangzhou, Guangdong Province, China. Symptoms were characterized by initial dryness of the twigs and eventual death of the whole branch of the tree. Isolations from symptomatic branches yielded 13 isolates including two main morphotypes. Pathogenicity tests showed that isolate GDOP1 from Type I caused dieback of O. pinnata. Based on morphological characteristics and molecular analysis of the internal transcribed spacer rDNA (ITS1-5.8S-ITS2) and partial sequence of the translation elongation factor 1α (EF1-α), the fungus causing dieback on O. pinnata was identified as Lasiodiplodia pseudotheobromae. This is the first report of L. pseudotheobromae infecting O. pinnata in the world.

Involvement of LaeA in the regulation of conidia production and stress responses in Penicillium digitatum.

Involvement of LaeA in various biological processes of filamentous fungi has been demonstrated. However, its role in Penicillium digitatum, the causal agent of citrus postharvest green mold, remains unclear. In this study, a ΔPdLaeA mutant was constructed using homologous recombination. The production of conidia by the ΔPdLaeA mutant was reduced by half compared with that of the wild-type strain. The sensitivity of the ΔPdLaeA mutant increased under alkaline conditions. The virulence assay revealed that PdLaeA was dispensable for the virulence of P. digitatum. Comparative transcriptome analysis revealed that the function loss of PdLaeA resulted in the reduced expression of several secondary metabolite gene clusters. In addition, expression of several key regulators of conidiation (BrlA, FlbA, FlbC, FlbD, and FluG) was also downregulated in the ΔPdLaeA mutant. In summary, the present work demonstrated that PdLaeA was involved in the regulation of SM biosynthesis, as well as the development and environmental adaptation of P. digitatum.

A Channel-Projection Mixed-Scale Convolutional Neural Network for Motor Imagery EEG Decoding.

Motor imagery electroencephalography (EEG) decoding is an essential part of brain-computer interfaces (BCIs) which help motor-disabled patients to communicate with the outside world by external devices. Recently, deep learning algorithms using decomposed spectrums of EEG as inputs may omit important spatial dependencies and different temporal scale information, thus generated the poor decoding performance. In this paper, we propose an end-to-end EEG decoding framework, which employs raw multi-channel EEG as inputs, to boost decoding accuracy by the channel-projection mixed-scale convolutional neural network (CP-MixedNet) aided by amplitude-perturbation data augmentation. Specifically, the first block in CP-MixedNet is designed to learn primary spatial and temporal representations from EEG signals. The mixed-scale convolutional block is then used to capture mixed-scale temporal information, which effectively reduces the number of training parameters when expanding reception fields of the network. Finally, based on the features extracted in previous blocks, the classification block is constructed to classify EEG tasks. The experiments are implemented on two public EEG datasets (BCI competition IV 2a and High gamma dataset) to validate the effectiveness of the proposed approach compared to the state-of-the-art methods. The competitive results demonstrate that our proposed method is a promising solution to improve the decoding performance of motor imagery BCIs.

A Parametric Time-Frequency Conditional Granger Causality Method Using Ultra-Regularized Orthogonal Least Squares and Multiwavelets for Dynamic Connectivity Analysis in EEGs.

OBJECTIVE: This study proposes a new parametric time-frequency conditional Granger causality (TF-CGC) method for high-precision connectivity analysis over time and frequency domain in multivariate coupling nonstationary systems, and applies it to source electroencephalogram (EEG) signals to reveal dynamic interaction patterns in oscillatory neocortical sensorimotor networks. METHODS: The Geweke's spectral measure is combined with the time-varying autoregressive with exogenous input (TVARX) modeling approach, which uses multiwavelet-based ultra-regularized orthogonal least squares (UROLS) algorithm, aided by adjustable prediction error sum of squares (APRESS), to obtain high-resolution time-varying CGC representations. The UROLS-APRESS algorithm, which adopts both the regularization technique and the ultra-least squares criterion to measure not only the signal themselves, but also the weak derivatives of them, is a novel powerful method in constructing time-varying models with good generalization performance, and can accurately track smooth and fast changing causalities. The generalized measurement based on CGC decomposition is able to eliminate indirect influences in multivariate systems. RESULTS: The proposed method is validated on two simulations, and then applied to source level motor imagery (MI) EEGs, where the predicted distributions are well recovered with high TF precision, and the detected connectivity patterns of MI-EEGs are physiologically interpretable and yield new insights into the dynamical organization of oscillatory cortical networks. CONCLUSION: Experimental results confirm the effectiveness of the TF-CGC method in tracking rapidly varying causalities of EEG-based oscillatory networks. SIGNIFICANCE: The novel TF-CGC method is expected to provide important information of neural mechanisms of perception and cognition.

Suppressing a plant-parasitic nematode with fungivorous behavior by fungal transformation of a Bt cry gene.

BACKGROUND: Pine wilt disease, caused by the pinewood nematode Bursaphelenchus xylophilus (PWN), is an important destructive disease of pine forests worldwide. In addition to behaving as a plant-parasitic nematode that feeds on epithelial cells of pines, this pest relies on fungal associates for completing its life cycle inside pine trees. Manipulating microbial symbionts to block pest transmission has exhibited an exciting prospect in recent years; however, transforming the fungal mutualists to toxin delivery agents for suppressing PWN growth has received little attention. RESULTS: In the present study, a nematicidal gene cry5Ba3, originally from a soil Bacillus thuringiensis (Bt) strain, was codon-preferred as cry5Ba3Φ and integrated into the genome of a fungus eaten by PWN, Botrytis cinerea, using Agrobacterium tumefaciens-mediated transformation. Supplementing wild-type B. cinerea extract with that from the cry5Ba3Φ transformant significantly suppressed PWN growth; moreover, the nematodes lost fitness significantly when feeding on the mycelia of the cry5Ba3Φ transformant. N-terminal deletion of Cry5Ba3Φ protein weakened the nematicidal activity more dramatically than did the C-terminal deletion, indicating that domain I (endotoxin-N) plays a more important role in its nematicidal function than domain III (endotoxin-C), which is similar to certain insecticidal Cry proteins. CONCLUSIONS: Transformation of Bt nematicidal cry genes in fungi can alter the fungivorous performance of B. xylophilus and reduce nematode fitness. This finding provides a new prospect of developing strategies for breaking the life cycle of this pest in pines and controlling pine wilt disease.

Complete Genome Sequence of Paenibacillus polymyxa CF05, a Strain of Plant Growth-Promoting Rhizobacterium with Elicitation of Induced Systemic Resistance.

Paenibacillus polymyxa CF05 is a Gram-positive rod-shaped bacterium isolated from the interior of an ancient tree, Cryptomeria fortunei, in China. This bacterium displays potent biocontrol effects against certain soil-borne diseases and the elicitation of induced systemic resistance in tomatoes. Here, we report the complete genome sequence of P. polymyxa CF05.

Complete Genome Sequence of Terribacillus aidingensis Strain MP602, a Moderately Halophilic Bacterium Isolated from Cryptomeria fortunei in Tianmu Mountain in China.

Terribacillus aidingensis strain MP602, which was isolated from an ancient tree (Cryptomeria forunei) in Tianmu Mountain in China, has antagonistic activity against several certain phytopathogenic fungi. Here, we report the genome sequence of this strain. This is the first complete genome report of the Terribacillus genus.