In fungi, the methylcitrate cycle converts cytotoxic propionyl-coenzyme A (CoA) to pyruvate, which enters gluconeogenesis. The glyoxylate cycle converts acetyl-CoA to succinate, which enters gluconeogenesis. The tricarboxylic acid cycle is a central carbon metabolic pathway that connects the methylcitrate cycle, the glyoxylate cycle, and other metabolisms for lipids, carbohydrates, and amino acids. Fungal citrate synthase and 2-methylcitrate synthase as well as isocitrate lyase and 2-methylisocitrate lyase, each evolved from a common ancestral protein. Impairment of the methylcitrate cycle leads to the accumulation of toxic intermediates such as propionyl-CoA, 2-methylcitrate, and 2-methylisocitrate in fungal cells, which in turn inhibits the activity of many enzymes such as dehydrogenases and remodels cellular carbon metabolic processes. The methylcitrate cycle and the glyoxylate cycle synergistically regulate carbon source utilization as well as fungal growth, development, and pathogenic process in pathogenic fungi.

RNA interference (RNAi) has emerged as a potent mechanism for combating pathogenic fungi and oomycetes over the past decades. It offers a promising gene-silencing approach by targeting crucial genes involved in diseases caused by economically and scientifically significant fungal pathogens, such as Botrytis cinerea and Fusarium species. Simultaneously, nano-agro-products have gained attention as alternatives to traditional fungicides in plant protection strategies. However, the instability of naked RNA molecules outside the cellular environment presents a challenge, as they degrade rapidly, limiting their efficacy for prolonged disease control. Concerns regarding the toxicity of protective nanoparticles to non-target organisms have also arisen. Integrating RNAi with nano-agro-products, particularly nanocarriers, to form RNA-nano complexes has demonstrated significant potential, providing enhanced RNA stability, reduced toxicity, and extended disease control. This review explores the mechanisms of RNA-nano complexes-mediated plant protection, addressing RNA stability and nano-toxicity issues while examining the prospects of RNA-nano complex research in plant pathogen management.

The sustainable utilization of rice straw is challenged by its recalcitrant lignocellulosic structure, especially under low-to-moderate field temperatures. In this study, a novel microbial consortium (SXJG15) mainly containing Sphingobacterium, Azospirillum, and Pseudomonas was enriched from overwintering rice stubble in Zhejiang, China, and evaluated for its rice straw degradation efficiency at 25 °C. Over an 18-day cultivation period, SXJG15 achieved a 52.5% degradation of total rice straw, including 60.2% cellulose, 76.3% hemicellulose, and 40.7% lignin. High extracellular enzymatic activities, including cellulases (up to 80.3 U/mL) and xylanases (up to 324.8 U/mL), were observed during the biodegradation process. 16S rRNA gene sequencing and metagenomics analyses revealed a succession of dominant taxa, including Sphingobacterium, Azospirillum, and Cellulomonas. Further, CAZy annotation indicated that the SXJG15 enzyme system was rich in glycoside hydrolases (42.7%) and glycosyltransferases (34.2%), demonstrating its high potential for lignocellulose degradation. This study uniquely demonstrates the mesophilic (moderate temperature 25 °C) efficiency of SXJG15 in lignocellulose breakdown, provides new insights into the microbial mechanisms of straw decomposition, and lays a foundation for bioenergy and soil fertility applications for developing a sustainable agriculture system.

The appressorium is a specialized structure that is differentiated from Magnaporthe oryzae spores that can infect host cells. In the process of cellular transformation from spore to appressorium, the contents inside the spores are transferred into appressoria, accompanied by major differences in the gene expression model. In this study, we reported a transcription factor (TF), Pcf1, which was depressed at the transcription level and degraded at the protein level in nuclei of incipient appressoria at four hpi (hours post inoculation). To investigate its degradation mechanism, the interacting proteins of Pcf1 were identified using an immunoprecipitation-mass spectrometry (IP-MS) assay. Yeast two-hybrid (Y2H) and co-IP (co-immunoprecipitation) assays confirmed that Pcf1 interacted with the casein kinase 2 (CK2) holoenzyme through direct combination with the CKb2 subunit. Moreover, Pcf1 was ubiquitinated in the hyphae. These changes in Pcf1 protein levels in nuclei provide a new clue of how TFs are degraded during appressorium formation: temporarily unnecessary TFs in spores are phosphorylated through interacting with CK2 enzyme and are then ubiquitinated and digested by the ubiquitin proteasome system (UPS).

Magnaporthe oryzae is the causal agent of rice blast, leading to significant reductions in rice and wheat productivity. Nap1 is a conserved protein in eukaryotes involved in diverse physiological processes, such as nucleosome assembly, histone shuttling between the nucleus and cytoplasm, transcriptional regulation, and the cell cycle. Here, we identified Nap1 and characterized its roles in fungal development and virulence in M. oryzae. MoNap1 is involved in aerial hyphal and conidiophore differentiation, sporulation, appressorium formation, plant penetration, and virulence. ΔMonap1 generated a small, elongated, and malformed appressorium with an abnormally organized septin ring on hydrophobic surfaces. ΔMonap1 was more sensitive to cell wall integrity stresses but more resistant to microtubule stresses. MoNap1 interacted with histones H₂A and H₂B and the B-type cyclin (Cyc1). Moreover, a nuclear export signal (NES) domain is necessary for Nap1’s roles in the regulation of the growth and pathogenicity of M. oryzae. In summary, NAP1 is essential for the growth, appressorium formation, and pathogenicity of M. oryzae.

Rice blast, caused by Magnaporthe oryzae, significantly threatens global rice production. Disease control is complicated by the pathogen’s high genetic diversity, which is driven by heterothallic recombination between opposite mating types that underlies variation. However, mechanisms governing sexual reproduction in this fungus remain poorly characterized, largely due to the absence of reliable methods for scalable ascospore progeny production. In this study, we established two novel mating methods, namely Conidial Mixing Mating (CMM) and Hyphal Segments Mixed Mating (HMM). Both methods employed optimized suspensions (5 × 10⁴ conidia/mL or equivalent hyphal density) mixed at 1:1 ratios, incubated under standardized conditions: 20 °C with a 12 h/12 h photoperiod. We characterized perithecia, asci, and ascospore morphology using fluorescence microscopy, paraffin sectioning, cryo-scanning electron microscopy, and transmission electron microscopy. Furthermore, both methods enabled phenotypic characterization of sexual reproduction-deficient mutants, including ΔMopmk1 and ΔMoopy2. In conclusion, we established two efficient methods for investigating M. oryzae sexual reproduction, providing foundational tools to advance studies of sexual mechanisms, pathogenicity evolution, and genetic variation.