Yujie Yang

Low temperature is a major abiotic stress that severely restricts plant growth, development, and geographical distribution. Although C2H2 zinc finger proteins have been widely implicated in regulating plant growth and responses to environmental stresses, their biological functions in Phoebe bournei remain largely unexplored. In this study, a total of 61 C2H2 genes were identified from the P. bournei genome and grouped into five phylogenetic clades. Comparative analyses of conserved motifs and exon–intron organization demonstrated that members within each clade share highly similar structural characteristics. Promoter analysis indicated that PnC2H2 genes are associated with stress‐ and hormone‐responsive elements. PnC2H2‐14 was strongly induced by cold stress and predominantly expressed in leaves. Subcellular localization confirmed that PnC2H2‐14 is a nuclear protein, while yeast assays demonstrated that it possesses no intrinsic transcriptional activation activity. Functional characterization revealed that ectopic expression of PnC2H2‐14 in tobacco markedly improved cold tolerance by limiting reactive oxygen species accumulation, enhancing antioxidant enzyme activities, and alleviating membrane injury during cold exposure. In addition, several antioxidant‐related genes were significantly upregulated in transgenic plants. These results suggest that PnC2H2‐14 positively regulates cold tolerance by enhancing antioxidant defense and maintaining ROS homeostasis. This study provides insights into the evolution and function of the C2H2 gene family in P. bournei and identifies candidate genes for improving cold resistance.

As a coastal brush, Atalantia buxifolia is a good rootstock of citrus plants around sea shores, but its salt tolerance has not been studied. In order to explore the salt tolerance of A. buxifolia, its seeds and seedlings were subjected to NaCl stress treatment, followed by phenotypic observation and biochemical and transcriptome analysis. Results showed that the increase in NaCl concentrations resulted in the decrease in germination rates, germination potential, germination index, and vigor index of A. buxifolia seeds, as well as growth of epicotyl and radicle, and biomass of A. buxifolia seedlings. However, the seeds of A. buxifolia could adapt to the growth of 100 mM NaCl concentration to a certain extent. The levels of malondialdehyde (MDA) and relative electrolyte leakage increased with the increase in NaCl concentrations. However, under treatment of 100 mM NaCl, the biomass, POD, CAT, APX, GSH, AsA, H₂O₂, MDA, and relative electrolyte leakage of A. buxifolia seedlings did not show significant changes compared with the control treatment. Transcriptome analysis showed that expression of differential genes increased with the increase in NaCl concentrations. GO enrichment showed that the most annotated genes were metabolic process, cell and cell composition, and binding. The KEGG pathway annotation shows that differential genes were mainly enriched in some pathways, such as photosynthesis antenna proteins, plant hormone signal transduction, glutathione metabolism, and starch and sucrose metabolism. In addition, differentially expressed genes had been annotated into 45 transcription factor families, including the largest number of bHLH, NAC, WRKY, MYB, and bZIP families. The results provide a basis for further understanding the salt tolerance mechanism and exploring related salt tolerance genes of A. buxifolia.

In the context of contemporary climate change, drought is widely recognized as a major stressor affecting plant growth. While numerous studies have demonstrated that Serendipita indica enhances stress resistance in host plants and is widely used in agriculture, research on its symbiotic interactions with woody plants for improving drought tolerance remains limited. This study investigated the effects of S. indica inoculation on the growth of Phoebe sheareri seedlings under varying drought conditions—well-watered (WW), moderate drought (MD), and severe drought (SD)—and explored the physiological mechanisms underlying improved drought resistance. The results showed that under WW conditions, S. indica inoculation promoted seedling growth and development. Under MD and SD conditions, although drought stress inhibited growth, inoculation significantly increased plant biomass, root parameters, chlorophyll content, and photosynthetic efficiency. Additionally, it alleviated drought-induced damage by reducing REC, MDA, H₂O₂, and O₂⁻ levels, while enhancing SOD, POD, and CAT activities, and increasing root ABA, GA, IAA, and CTK content. Under MD stress, adaptive changes in root architecture and hormone levels were observed, including increases in total root length, surface area, volume, average diameter, and elevated IAA and CTK levels—all of which were further enhanced by S. indica inoculation. In conclusion, symbiosis with S. indica improved drought tolerance in P. sheareri seedlings likely through enhanced photosynthesis, antioxidant enzyme activity, and hormone regulation.

The establishment of artificial grassland is a good pathway for resolving serious social and economic problems in the Qinghai–Tibet Plateau. Some beneficial indigenous microbes may be used to improve productivity in artificial grassland. The genome of the indigenous dark septate fungus, Exophiala tremulae CICC2537, was sequenced and assembled at the chromosome level using the PacBio sequencing platform, with the assistance of the Hi-C technique for scaffolding, and its 3D genome structures were investigated. The genome size of E. tremulae is 51.903848 Mb, and it contains eight chromosomes. A total of 12,277 protein-coding genes were predicted, and 11,932 genes (97.19%) were annotated. As for the distribution of exon and intron number and the distribution of gene GC and CDS GC, E. tremulae showed similar distribution patterns to the other investigated members of the genus Exophiala. The analysis of carbohydrate-active enzymes showed that E. tremulae possesses the greatest number of enzymes with auxiliary activities and the lowest number of enzymes with carbohydrate-binding modules among the investigated fungi. The total number of candidate effector proteins was 3337, out of which cytoplasmic and apoplastic effector proteins made up 3100 and 163, respectively. The whole genome of E. tremulae contained 40 compartment As and 76 compartment Bs, and there was no significant difference in GC content in its compartment As and Bs. The whole genome of E. tremulae was predicted to contain 155 topologically associating domains (TADs), and their average length was 250,000 bp, but there were no significant differences in the numbers of genes and the GC content per bin localized within the boundaries and interiors of TADs. Comparative genome analysis showed that E. tremulae diverged from Exophiala mesophila about 34.1 (30.0–39.1) Myr ago, and from Exophiala calicioides about 85.6 (76.1–90.6) Myr ago. Compared with all the investigated fungi, the numbers of contraction and expansion gene families in the E. tremulae genome were 13 and 89, respectively, and the numbers of contraction and expansion genes were 14 and 670, respectively. Our work provides a basis for the use of the dark septate fungus in alpine artificial grassland and further research into its symbiosis mechanisms, which may improve the growth of plant species used in the Qinghai–Tibet Plateau.

Aims Acorus calamus is widely recognized for its therapeutic potential in treating neurological, cardiovascular, and gastrointestinal disorders. Serendipita indica has been shown to promote growth and enhance secondary metabolite production in several plants; however, it is unknown whether S. indica remain beneficial effects on A. calamus. Methods A. calamus was cultured in soil with or without S. indica to assess changes in photosynthesis, biomass, and secondary metabolites. The cultivars were grown in a growth chamber in a completely randomized design with two treatment groups: inoculated and non-inoculated, each with three replications. Successful colonization was confirmed microscopically, distinguishing between control (CK) and experimental (P+) groups. Results The roots of A. calamus can be colonized by S. indica. Results showed an increase in stem length, creeping stem branches, and root surface area post-colonization after inoculation with S. indica. Meanwhile, the colonization of S. indica in A. calamus roots led to improve photosynthetic efficiency, reflected by increased photosynthetic rate, intercellular CO₂ concentration, stomatal conductance, and transpiration rate. Furthermore, among the 170 compounds identified in A. calamus, 25 showed increased levels post-inoculation, including lipids, acids, sugars, amino acids and their derivatives, saponins, phenols, alcohols, flavonoids, aldehydes, sterols, heterocyclic compounds, fatty acid ethanolamides, hydrocarbons, alkaloids, phenylpropanoids, and ketones. Conclusion These results underscore the potential of S. indica in enhancing the medicinal properties of A. calamus, suggesting a promising avenue for its agricultural and pharmacological applications.

Pinus taeda is an important forest tree species for plantations because of its rapid growth and high yield of oleoresins. Although P. taeda plantations distribute in warm and wet southern China, drought, sometime serious and long time, often occurs in the region. To explore drought tolerance of P. taeda and usage of beneficial microorganisms, P. taeda seedlings were planted in pots and were inoculated with root endophytic fungus Serendipita indica and finally were treated with drought stress for 53 d. Metabolome and proteome of their needles were analyzed. The results showed that S. indica inoculation of P. taeda seedlings under drought stress caused great changes in levels of some metabolites in their needles, especially some flavonoids and organic acids. Among them, the levels of eriocitrin, trans-aconitic acid, vitamin C, uric acid, alpha-ketoglutaric acid, vitamin A, stachydrine, coumalic acid, itaconic acid, calceolarioside B, 2-oxoglutaric acid, and citric acid were upregulated more than three times in inoculated seedlings under drought stress, compared to those of non-inoculated seedlings under drought stress. KEGG analysis showed that some pathways were enriched in inoculated seedlings under drought stress, such as flavonoid biosynthesis, ascorbate and aldarate metabolism, C5-branched dibasic acid metabolism. Proteome analysis revealed some specific differential proteins. Two proteins, namely, H9X056 and H9VDW5, only appeared in the needles of inoculated seedlings under drought stress. The protein H9VNE7 was upregulated more than 11.0 times as that of non-inoculated seedlings under drought stress. In addition, S. indica inoculation increased enrichment of water deficient-inducible proteins (such as LP3-1, LP3-2, LP3-3, and dehydrins) and those involved in ribosomal structures (such as A0A385JF23). Meanwhile, under drought stress, the inoculation caused great changes in biosynthesis and metabolism pathways, mainly including phenylpropanoid biosynthesis, cutin, suberine and wax biosynthesis, and 2-oxocarboxylic acid metabolism. In addition, there were positive relationships between accumulation of some metabolites and enrichment of proteins in P. taeda under drought stress. Altogether, our results showed great changes in metabolome and proteome in inoculated seedlings under drought stress and provided a guideline to further study functions of metabolites and proteins, especially those related to drought stress.

Pestalotiopsis species have gained attention thanks to their structurally complex and biologically active secondary metabolites. In past decades, several new secondary metabolites were isolated and identified. Their bioactivities were tested, including anticancer, antifungal, antibacterial, and nematicidal activity. Since the previous review published in 2014, new secondary metabolites were isolated and identified from Pestalotiopsis species and unidentified strains. This review gathered published articles from 2014 to 2021 and focused on 239 new secondary metabolites and their bioactivities. To date, 384 Pestalotiopsis species have been discovered in diverse ecological habitats, with the majority of them unstudied. Some may contain secondary metabolites with unique bioactivities that might benefit pharmacology.