Indole-3-acetic acid (IAA) belongs to the family of auxin indole derivatives. IAA regulates almost all aspects of plant growth and development, and is one of the most important plant hormones. In microorganisms too, IAA plays an important role in growth, development, and even plant interaction. Therefore, mechanism studies on the biosynthesis and functions of IAA in microorganisms can promote the production and utilization of IAA in agriculture. This mini-review mainly summarizes the biosynthesis pathways that have been reported in microorganisms, including the indole-3-acetamide pathway, indole-3-pyruvate pathway, tryptamine pathway, indole-3-acetonitrile pathway, tryptophan side chain oxidase pathway, and non-tryptophan dependent pathway. Some pathways interact with each other through common key genes to constitute a network of IAA biosynthesis. In addition, functional studies of IAA in microorganisms, divided into three categories, have also been summarized: the effects on microorganisms, the virulence on plants, and the beneficial impacts on plants.

The primary functions of mitochondria are to produce energy and participate in the apoptosis of cells, with them being highly conserved among eukaryotes. However, the composition of mitochondrial genomes, mitochondrial DNA (mtDNA) replication, and mitochondrial inheritance varies significantly among animals, plants, and fungi. Especially in fungi, there exists a rich diversity of mitochondrial genomes, as well as various replication and inheritance mechanisms. Therefore, a comprehensive understanding of fungal mitochondria is crucial for unraveling the evolutionary history of mitochondria in eukaryotes. In this review, we have organized existing reports to systematically describe and summarize the composition of yeast-like fungal mitochondrial genomes from three perspectives: mitochondrial genome structure, encoded genes, and mobile elements. We have also provided a systematic overview of the mechanisms in mtDNA replication and mitochondrial inheritance during bisexual mating. Additionally, we have discussed and proposed open questions that require further investigation for clarification.

Manuka honey (MH) is increasingly recognized for its potent antioxidant properties, making it a promising functional food ingredient. However, discrepancies in assessment methods have impeded the standardization of its antioxidant capacity. This study compared DPPH, ABTS, and cellular antioxidant activity (CAA) assays under varying conditions to identify the most reliable approach for assessing MH’s antioxidant properties. The results showed that the reaction temperature for the chemical method, setting it at 37 °C, enhanced the antioxidant capacity of MH. For the cellular assay, we optimized honey concentration, injury duration, damage model, and cell model. The result showed that sugar-reduced MH achieved the same high efficiency as the chemical method. A stable cellular assay method was established in HepG2 cells, offering superior reproducibility with an intra-RSD of 4.83% (<5%) and an inter-RSD of 7.51% (<10%). Additionally, studies have found that methyl syringate (MSY), a key polyphenolic compound in Manuka honey (MH), exhibits extremely high antioxidant activity. However, due to its low concentration, its overall contribution to the honey’s antioxidant activity is limited. This optimized CAA-based approach provides reliable technical support for the accurate evaluation of the antioxidant activity of MH.

Citrus Alternaria brown spot caused by the necrotrophic fungal pathogen of the tangerine pathotype of Alternaria alternata causes yield losses in global tangerine production. In this study, we focus on a cytochrome P450 monooxygenase encoding gene, Aacp1, for its role in the sporulation, toxin production, and virulence of the tangerine pathotype of Alternaria alternata. Aacp1-deficient mutants (∆Aacp1) produced significantly fewer conidia than the wild-type strain. Chemical assays demonstrated that Aacp1 plays a negative role in resistance to oxidant stress and biosynthesis of ACT toxin. Virulence assays revealed that ΔAacp1 fails to induce necrotic lesions on detached Hongjv leaves. Transcriptomic analyses of WT and ΔAacp1 revealed that many metabolic process genes were regulated. Furthermore, our results revealed a previously unrecognized Aacp1 affected the expression of the gene encoding a naphthalene dioxygenase (AaNdo1) for sporulation and full virulence. Overall, this study revealed the diverse functions of cytochrome P450 monooxygenase in the phytopathogenic fungus.

The Chinaberry tree, a member of the Meliaceae family, is cultivated in China for use in traditional medicines. In 2020, Chinaberry trees with leaf deformation symptoms were found in Hangzhou, Zhejiang province, China. In order to identify possible pathogenic viruses, a symptomatic sample was subjected to deep sequencing of small interfering RNAs. Assembly of the resulting sequences led to the identification of a novel badnavirus, provisionally designated Chinaberry tree badnavirus 1 (ChTBV1). With the recent development of China’s seedling industry and increasing online shopping platforms, the risk of tree virus transmission has increased substantially. Therefore, it is important to detect the occurrence of ChTBV1 to ensure the safety of the Chinaberry tree seedling industry. Here, we describe the development and validation of a sensitive and robust method relying on a loop-mediated isothermal amplification (LAMP) assay, targeting a 197 nt region, to detect ChTBV1 from Chinaberry tree leaves. The LAMP assay was also adapted for rapid visualization of results by a lateral flow dipstick chromatographic detection method.

Citrus alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is one of the most severe fungal diseases affecting citrus crops. Currently, there is a critical need for rapid and visual detection techniques to identify the tangerine pathotype of A. alternata. In this study, a novel detection system was developed by combining recombinase polymerase amplification (RPA) with CRISPR/Cas12a technology, targeting the ACTT3 gene specific to the tangerine pathotype of A. alternata. Through optimization of reaction time and component concentrations, the assay demonstrated a detection sensitivity of 1 pg μL⁻¹ within 40 min at a constant temperature of 37 °C. The results can be visually interpreted using nucleic acid test strips, offering advantages in specificity, sensitivity, and speed. This system has been successfully validated for the rapid detection of the pathogen within plant tissues, including leaves and fruits, providing an efficient and practical solution for real-time field detection of the tangerine pathotype of A. alternata.