Xiaodong Ma

White rot fungi and soil microbial communities at the hyphosphere influence phosphorus availability through their interactions. However, the mechanisms underlying the effects of different phosphorus forms on polycyclic aromatic hydrocarbons (PAHs) during plant-white rot fungus remediation remain unclear. Thus, this study aimed to investigate the effects of different phosphorus addition forms on soil microbial community diversity during plant-white rot fungus remediation and their correlation with PAH biodegradation through amplicon high-throughput sequencing. Pot experiments were conducted in a greenhouse. Salix viminalis was cultivated under two fungal levels (inoculated and non-inoculated with Crucibulum laeve) and three phosphorus levels (no phosphorus addition, potassium dihydrogen phosphate addition, and calcium phytate addition) to remediate phenanthrene (PHE)-contaminated soil. Among the treatments, two potassium dihydrogen phosphate addition treatments exhibited the highest PHE removal rates (74.0% and 79.4%) on day 60. Inoculation with C. laeve significantly increased the relative abundance of Pseudomonas but antagonized other putative indigenous PAH-degrading taxa. Potassium dihydrogen phosphate addition alleviated the antagonistic effect of C. laeve and indigenous microorganisms and synergistically promoted PHE degradation in soil with C. laeve, whereas calcium phytate addition did not significantly improve soil PHE removal rates. Additionally, the simultaneous phosphorus addition and C. laeve inoculation created a unique microbial community structure that facilitated organic phosphorus activation and accelerated phosphorus turnover. However, PHE degradation varied depending on the phosphorus form. Therefore, the addition of soluble phosphorus should be prioritized over insoluble phosphorus to optimize plant-white rot fungus remediation.

Long-term industrialization has led to high HCHO concentrations in North China. In this study, we analyzed the spatial and temporal distribution characteristics of tropospheric HCHO VCD and its driving factors in North China from 2019 to 2023 based on the HCHO daily dataset from TROPOMI. The results showed that the spatial distribution trend of tropospheric HCHO VCD in North China remained unchanged in the past 5 years, with the highest in the center, followed by the east and the lowest in the west. Seasonal variations were clearly characterized, with summer being higher than other seasons and spring being the lowest. In addition, the effects of meteorological elements on HCHO VCD were analyzed based on the ERA5 dataset, and the correlation between HCHO VCD and temperature and wind was strong, while the correlation with precipitation and surface solar radiation was low, and the effects were obviously different between the growing and non-growing seasons. Population density is directly proportional to tropospheric HCHO VCD. In this study, a higher-resolution spatial and temporal distribution model of tropospheric HCHO VCD in North China is obtained based on TROPOMI, which effectively characterizes the driving factors of HCHO VCD.

Chromosome traits may differ between closely related ferns growing in different geological landscapes. Adiantum series Gravesiana (Pteridaceae) includes six species, of which, five species are exclusively distributed in Karst landforms, and one, Adiantum juxtapositum, grows on Danxia landform. Additionally, there are some populations or individuals whose morphology are between different species, which may be the results of polyploidization or hybridization. Here we studied chromosome numbers of species in series Gravesiana primarily using crosiers. Results are: A. longzhouensis and A. juxtapositum were diploids with 2n = 60 and 2n = 64, respectively; A. dentatum was deduced to be diploids with 2n = ca. 60; A. mariesii had two cytotypes, 2n = 60 (diploid) and 2n = ca. 120 (tetraploid), respectively; A. gravesii had four cytotypes including 2n = ca. 60 (diploid), ca. 120 (tetraploid), ca. 150 (pentaploid), and ca. 180 (hexaploid). All these different cytotypes suggest polyploidization and hybridization have occurred in A. gravesii and A. mariesii, so we treated these two species as two “complex group”. All chromosome numbers in this study are the first record.

Although plant-white-rot fungi (WRF) remediation is considered efficient in improving polycyclic aromatic hydrocarbon (PAH)–contaminated soil, the prospects for using it remain poorly known. Therefore, we evaluated whether the WRF Crucibulum laeve could improve the phytoremediation of PAH-contaminated soil by Salix viminalis L. A 60-day pot experiment was conducted to investigate the effects of C. laeve inoculation (using two inoculation treatments and a non-inoculated control) on the phytoremediation potential, growth, and antioxidant metabolism of S. viminalis cultivated in PAH-contaminated soil. The S. viminalis-C. laeve association synergistically caused the highest PAH removal rate. Under the S. viminalis-C. laeve treatment, 80% of the biological concentration and translocation factors for all tissues of S. viminalis were > 1, whereas only 20% of these factors were > 1 when S. viminalis was used alone. C. laeve inoculation remarkably enhanced phytoremediation by promoting S. viminalis–based phytoextraction of PAHs from soils. Furthermore, although C. laeve inoculation altered the antioxidant metabolism of S. viminalis by inducing oxidative stress, thereby inhibiting plant growth, the plant’s hardiness enabled it to survive and grow normally for 60 days after treatment. Therefore, phytoremediation using S. viminalis inoculated with C. laeve can be considered a feasible approach for the phytoremediation of PAH-contaminated soil.

Methyl-CpG-binding domain (MBD) proteins have diverse molecular and biological functions in plants. Most studies of MBD proteins in plants have focused on the model plant Arabidopsis thaliana L. Here we cloned SvMBD5 from the willow Salix viminalis L. by reverse transcription-polymerase chain reaction (RT-PCR) and analyzed the structure of SvMBD5 and its evolutionary relationships with proteins in other species. The coding sequence of SvMBD5 is 645 bp long, encoding a 214 amino acid protein with a methyl-CpG-binding domain. SvMBD5 belongs to the same subfamily as AtMBD5 and AtMBD6 from Arabidopsis. Subcellular localization analysis showed that SvMBD5 is only expressed in the nucleus. We transformed Arabidopsis plants with a 35S::SvMBD5 expression construct to examine SvMBD5 function. The Arabidopsis SvMBD5-expressing line flowered earlier than the wild type. In the transgenic plants, the expression of FLOWERING LOCUS T and CONSTANS significantly increased, while the expression of FLOWERING LOCUS C greatly decreased. In addition, heterologously expressing SvMBD5 in Arabidopsis significantly inhibited the establishment and maintenance of methylation of CHROMOMETHYLASE 3 and METHYLTRANSFERASE 1, as well as their expression, and significantly increased the expression of the demethylation-related genes REPRESSOR OF SILENCING1 and DEMETER-LIKE PROTEIN3. Our findings suggest that SvMBD5 participates in the flowering process by regulating the methylation levels of flowering genes, laying the foundation for further studying the role of SvMBD5 in regulating DNA demethylation.