Summary: MicroRNA482/2118 (miR482/2118) is a 22‐nt miRNA superfamily, with conserved functions in disease resistance and plant development. It usually instigates the production of phased small interfering RNAs (phasiRNAs) from its targets to expand or reinforce its silencing effect. Using a new high‐quality reference genome sequence and comprehensive small RNA profiling, we characterized a newly evolved regulatory pathway of miR482/2118 in litchi. In this pathway, miR482/2118 cleaved a novel noncoding trans‐acting gene (LcTASL1) and triggered phasiRNAs to regulate the expression of gibberellin (GA) receptor gene GIBBERELLIN INSENSITIVE DWARF1 (GID1) in trans; another trans‐acting gene LcTASL2, targeted by LcTASL1‐derived phasiRNAs, produced phasiRNAs as well to target LcGID1 to reinforce the silencing effect of LcTASL1. We found this miR482/2118‐TASL‐GID1 pathway was likely involved in fruit development, especially the seed development in litchi. In vivo construction of the miR482a‐TASL‐GID1 pathway in Arabidopsis could lead to defects in flower and silique development, analogous to the phenotype of gid1 mutants. Finally, we found that a GA‐responsive transcription factor, LcGAMYB33, could regulate LcMIR482/2118 as a feedback mechanism of the sRNA‐silencing pathway. Our results deciphered a lineage‐specifically evolved regulatory module of miR482/2118, demonstrating the high dynamics of miR482/2118 function in plants.

Background: Dendrobium officinale Kimura et Migo, a renowned traditional Chinese orchid herb esteemed for its significant horticultural and medicinal value, thrives in adverse habitats and contends with various abiotic or biotic stresses. Acid invertases (AINV) are widely considered enzymes involved in regulating sucrose metabolism and have been revealed to participate in plant responses to environmental stress. Although members of AINV gene family have been identified and characterized in multiple plant genomes, detailed information regarding this gene family and its expression patterns remains unknown in D. officinale, despite their significance in polysaccharide biosynthesis. Results: This study systematically analyzed the D. officinale genome and identified four DoAINV genes, which were classified into two subfamilies based on subcellular prediction and phylogenetic analysis. Comparison of gene structures and conserved motifs in DoAINV genes indicated a high-level conservation during their evolution history. The conserved amino acids and domains of DoAINV proteins were identified as pivotal for their functional roles. Additionally, cis-elements associated with responses to abiotic and biotic stress were found to be the most prevalent motif in all DoAINV genes, indicating their responsiveness to stress. Furthermore, bioinformatics analysis of transcriptome data, validated by quantitative real-time reverse transcription PCR (qRT-PCR), revealed distinct organ-specific expression patterns of DoAINV genes across various tissues and in response to abiotic stress. Examination of soluble sugar content and interaction networks provided insights into stress release and sucrose metabolism. Conclusions: DoAINV genes are implicated in various activities including growth and development, stress response, and polysaccharide biosynthesis. These findings provide valuable insights into the AINV gene amily of D. officinale and will aid in further elucidating the functions of DoAINV genes.

Loquat (Eriobotrya japonica), an economically important evergreen fruit tree, exhibits an unusual reproductive cycle characterized by autumn–winter flowering and spring fruit maturation. However, the endogenous hormonal basis underlying this distinctive developmental pattern remains poorly understood, partly due to the lack of reliable multi-hormone analytical platforms for complex perennial fruit tissues. In this study, we established a robust targeted UHPLC-QQQ-MS/MS method for the simultaneous quantification of 11 endogenous phytohormones and related metabolites, including indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellins (GA₁, GA₃, GA₄, and GA₇), and cytokinins (tZR, iPR, DHZ, iP, and zeatin). Sample preparation and chromatographic conditions were systematically optimized to improve extraction efficiency, to reduce matrix interference, and to maximize detection sensitivity. The method exhibited high linearity (R² > 0.990), satisfactory recoveries (80.02–120.09%), low limits of detection, and high repeatability. Application of this platform to eight different loquat tissues revealed pronounced tissue-specific patterns of phytohormone distribution. Seeds contained exceptionally high levels of GA₃ and zeatin, whereas stamens exhibited marked enrichment of IAA. Mature leaves showed relatively high ABA levels, whereas fruit flesh retained substantial cytokinin pools. These findings provide a reliable analytical workflow for phytohormone quantification in perennial fruit crops and establish a foundational dataset of tissue-specific hormone distribution in loquat, which may serve as a valuable reference for future studies on reproductive development and horticultural trait improvement.