The current investigation utilized stem nodes from pre-established aseptic lines of Mussaenda pubescens as explants to optimize an efficient in vitro propagation protocol and investigated the effect of different light qualities (white, red, blue, and green) on metabolite accumulation in micropropagated plantlets. The findings demonstrated that the optimal medium for shoot proliferation was Murashige and Skoog basal medium supplemented with 6-Benzylaminopurine 2.0 mg·L⁻¹ and α-naphthaleneacetic acid 0.2 mg·L⁻¹, achieving a multiplication coefficient of 12.2 after 30 days. Rooting was more effective on Murashige and Skoog basal medium containing α-naphthaleneacetic acid 0.1 mg·L⁻¹ and activated charcoal 1 g·L⁻¹, resulting in a 100% rooting rate. During acclimatization, a substrate mixture of perlite:vermiculite: peat soil (1:1:1) promoted vigorous root development with a 100% survival rate at post-transplantation. Light quality significantly influenced plant morphology: red light stimulated stem elongation, while blue light increased biomass accumulation. Broad-target metabolomics revealed distinct metabolite profiles under different light spectra, with differentially accumulated metabolites primarily belonging to terpenoids, organic acids, lipids, and flavonoids. Specifically, red light enhanced the levels of terpenoids and lipids; blue light promoted the synthesis of specific triterpenoid saponins and lipids; while green light increased the content of certain terpenes and broadly upregulated a wide spectrum of lipids. This work provides a robust framework for the commercial micropropagation of Mussaenda pubescens and elucidates the strategic use of light quality to enhance the production of its valuable medicinal metabolites, including terpenoids and lipids.

Dimocarpus longan Lour. is an evergreen tree of the genus Longan in the Sapindaceae family, native to tropical and subtropical regions. Longan embryonic development is closely related to fruit set and fruit quality. An in-depth study of the mechanism of longan embryonic development could therefore contribute to the development of the longan industry. DIMBOA is the principal compound representing benzoxazinoids (BXs), and is closely linked to auxin biosynthesis and signal transduction. Auxin is one of the crucial hormones for inducing somatic embryogenesis (SE) in plants. Previous research has shown that DIMBOA promotes morphogenesis in the early somatic embryogenesis of longan, but the specific regulatory mechanism has not yet been clarified. To elucidate the molecular mechanism by which DIMBOA affects early somatic embryogenesis in longan, we chose longan embryogenic cultures grown under 0 mg/L DIMBOA as the control group (the check, CK), and longan embryogenic cultures grown under 0.1 mg/L DIMBOA as the treatment group (D) to be analyzed by transcriptomic sequencing. A total of 478 differentially expressed genes (DEGs) are detected in check vs. D, of which 193 are upregulated and 285 are downregulated. These DEGs are significantly enriched in the biosynthetic and metabolic functions of various substances such as vitamin B₆ (VB₆) biosynthesis, phenylpropanoid pathways, and carbohydrate metabolism. DIMBOA affects SE processes in longan via TFs, including MYB, ZF, bHLH, LBD, NAC, WRKY, etc. After DIMBOA treatment, the expression of most of the key genes for IAA synthesis was significantly downregulated, VB₆ content was significantly reduced, and H₂O₂ content was significantly increased. Therefore, it is suggested that DIMBOA directly or indirectly affects the H₂O₂ content through the VB₆ metabolic pathway, thereby regulating the endogenous IAA level to modulate the early SE morphogenesis of longan.

Dwarfing is one of the common phenotypic variations in asexually reproduced progeny of banana, and dwarfed banana is not only windproof and anti-fallout but also effective in increasing acreage yield. As a key gene in the strigolactone signalling pathway, DWARF53 (D53) plays an important role in the regulation of the height of plants. In order to gain insight into the function of the banana D53 gene, this study conducted genome-wide identification of banana D53 gene based on the M. acuminata, M. balbisiana and M. itinerans genome database. Analysis of MaD53 gene expression under high temperature, low temperature and osmotic stress based on transcriptome data and RT-qPCR was used to analyse MaD53 gene expression in different tissues as well as in different concentrations of GA and SL treatments. In this study, we identified three MaD53, three MbD53 and two MiD53 genes in banana. Phylogenetic tree analysis showed that D53 Musa are equally related to D53 Asparagales and Poales. Both high and low-temperature stresses substantially reduced the expression of the MaD53 gene, but osmotic stress treatments had less effect on the expression of the MaD53 gene. GR24 treatment did not significantly promote the height of the banana, but the expression of the MaD53 gene was significantly reduced in roots and leaves. GA treatment at 100 mg/L significantly promoted the expression of the MaD53 gene in roots, but the expression of this gene was significantly reduced in leaves. In this study, we concluded that MaD53 responds to GA and SL treatments, but “Yinniaijiao” dwarf banana may not be sensitive to GA and SL.

Banana productivity is severely limited by drought, yet the molecular basis of drought adaptation and endophyte-mediated stress alleviation remains poorly understood. Here, we performed a genome-wide analysis of the SQUAMOSA promoter-binding protein-like (SPL) transcription factor family in Musa acuminata and examined their transcriptional responses to drought stress and Serendipita indica inoculation. We identified 38 MaSPL genes, all encoding proteins with the conserved SBP domain and predicted nuclear localization. Phylogenetic, motif, gene structure, and collinearity analyses indicated that MaSPL genes are evolutionarily conserved, unevenly distributed across chromosomes, and expanded primarily through segmental duplication under purifying selection. Promoter analysis showed several cis-acting elements and transcription factor binding sites related to light, phytohormone, and stress signaling. Ten MaSPL genes were predicted as putative targets of miR156. qRT-PCR analysis showed that drought stress markedly downregulated the tested MaSPL genes, whereas miR156a expression increased, supporting an inverse regulatory relationship. Under drought, S. indica inoculation enhanced expression of most tested MaSPLs, restoring transcript accumulation while reducing miR156a to near-basal levels. Notable responses were observed in members of the MaSPL2, MaSPL9, and MaSPL13, respectively. S. indica improves drought tolerance by enhancing antioxidant defenses, reducing oxidative stress, and preserving photosynthetic and osmotic stability. Taken together, our results demonstrate that S. indica confers drought resilience in banana by counteracting drought-induced repression of MaSPL genes via the miR156–SPL module and by strengthening key physiological defense mechanisms.