The transcriptional landscape of Populus pattern/effector-triggered immunity and how PagWRKY18 involved in it.

Plants trigger a robust immune response by activating massive transcriptome reprogramming through crosstalk between PTI and ETI. However, how PTI and ETI contribute to the quantitative or/and qualitative output of immunity and how they work together when both are being activated were unclear. In this study, we performed a comprehensive overview of pathogen-triggered transcriptomic reprogramming by analyzing temporal changes in the transcriptome up to 144 h after Colletotrichum gloeosporioides inoculated in Populus. Moreover, we constructed a hierarchical gene regulatory network of PagWRKY18 and its potential target genes to explore the underlying regulatory mechanisms of PagWRKY18 that are not yet clear. Interestingly, we confirmed that PagWRKY18 protein can directly bind the W-box elements in the promoter of a transmembrane leucine-rich repeat receptor-like kinase, PagSOBIR1 gene, to trigger PTI. At the same time, PagWRKY18 functions in disease tolerance by modulation of ROS homeostasis and induction of cell death via directly targeting PagGSTU7 and PagPR4 respectively. Furthermore, PagPR4 can interact with PagWRKY18 to inhibit the expression of PagPR4 genes, forming a negative feedback loop. Taken together, these results suggest that PagWRKY18 may be involved in regulating crosstalk between PTI and ETI to activate a robust immune response and maintain intracellular homeostasis.

Soil Layers Impact Lithocarpus Soil Microbial Composition in the Ailao Mountains Subtropical Forest, Yunnan, China.

Plant litter decomposition is a complex, long-term process. The decomposition of litterfall is a major process influencing nutrient balance in forest soil. The soil microbiome is exceptionally diverse and is an essential regulator of litter decomposition. However, the microbiome composition and the interaction with litterfall and soil remain poorly understood. In this study, we examined the bacterial and fungal community composition of Lithocarpus across soil samples from different sampling seasons. Our results displayed that the microbiome assembly along the soil layer is influenced predominantly by the soil layer rather than by the sampling season. We identified that the soil layer strongly affected network complexity and that bacterial and fungal microbiomes displayed different patterns in different soil layers. Furthermore, source tracking and community composition analysis indicated that there are significantly different between soil and litter. Moreover, our results demonstrate that few dominant taxa (2% and 4% of bacterial and fungal phylotypes) dominated in the different soil layers. Hydnodontaceae was identified as the most important biomarker taxa for humic fragmented litter fungal microbiome and Nigrospora and Archaeorhizomycetaceae for organic soil and the organic mineral soil layer, and the phylum of Acidobacteria for the bacteria microbiome. Our work provides comprehensive evidence of significant microbiome differences between soil layers and has important implications for further studying soil microbiome ecosystem functions.