The MYB transcription factor family plays a crucial regulatory role in plant growth, development, biological progress, and stress responses. Here, we identified a R2R3-MYB transcription factor gene, SlMYB78-like, from tomato and characterized its function by gene silencing via RNA interference (RNAi). The results exhibited that the silencing of SlMYB78-like reduced the sensitivity of tomato seedlings to exogenous ABA. In addition, when exposed to drought and salt stresses, the RNAi lines grown in soil showed decreased tolerance, with lower ABA accumulation, relative water content, and chlorophyll content while displaying higher relative conductivity and malondialdehyde (MDA) content than the wild type. Moreover, the expression of genes related to chlorophyll biosynthesis, photosynthesis, and ABA biosynthesis/response were down-regulated in SlMYB78-like-silenced lines. Notably, the transcript level of SlCYP707-A2, which encodes a protein involved in ABA degradation, was up-regulated significantly after stresses. The transient expression assay Dual-luciferase (Dual-LUC) and a yeast one-hybrid (Y1H) assay demonstrated that SlMYB78-like bound to the promoter of SlCYP707-A2. Additionally, the physical interaction between SlMYB78-like and SlDREB3, which functioned in ABA signaling transduction, was identified through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Collectively, our study illustrates that SlMYB78-like participates in the abiotic stress response via the ABA pathway.

MADS-box transcription factors play a vital role in the development of reproductive organs and fruits. However, the mechanisms by which MADS-box transcription factors participate in determining the size of organs remain incompletely understood. This study demonstrated that the overexpression of SlMADS48 results in elongated sepals and is accompanied by an elevated gibberellin content, compared with the wild type (WT). The interaction between SlMADS48 and several proteins (SlMC, SlMBP21, SlJOINTLESS, and SlFYFL) involved in sepal development was identified. In addition, the OE-SlMADS48 lines exhibited increased branches and total numbers of flowers. Molecular analysis revealed that SlMADS48 interacted with TM29, FUL1, FUL2, and MBP20, which are associated with inflorescence development. Moreover, SlMDS48 directly targeted the promoter of SlTM3 via the CArG-box motif, reducing its transcript levels. Additionally, the overexpression of SlMADS48 led to a reduction in the size of fruit, together with decreased contents of cytokinins and indole acetic acid (IAA) compared with the WT. Furthermore, SlMADS48 directly combined with the promoters of SlcycD6;1 and SlIAA29 in the cytokinin and auxin pathways, respectively. This research advanced our understanding of SlMADS48’s role in determining organ size and provided valuable insights into target gene selection in tomato breeding programs.

Hippeastrum, a perennial herbaceous plant belonging to the Amaryllidaceae family, is widely cultivated for its large, vibrant flowers with diverse petal colors, which have significant ornamental and economic value. However, the mechanisms underlying anthocyanin accumulation in Hippeastrum petals remain poorly understood. To fully explore the involved regulation mechanism was significant for the breeding of Hippeastrum and other Amaryllidaceae family plants. In this study, we selected six Hippeastrum cultivars with distinctly different petal colors. We used metabolomic profiling and high-throughput transcriptomic sequencing to assess varied anthocyanin profiles and associated expression of genes in their biosynthetic pathways. Four key anthocyanins were identified: cyanidin, cyanidin-3-O-rutinoside, delphinidin-3-glucoside, and delphinidin-3-rutinoside. Weighted gene co-expression network analysis (WGCNA) correlated the abundance of these four anthocyanins with transcriptomic data, to suggest three regulatory modules. Nine transcription factors families in these modules were identified and some of them were validated using qRT-PCR. Y2H assay isolated some transcription factors interacted with TTG1 (WD40 protein), including MYB3/39/44/306 and bHLH13/34/110, illustrating the possibility of forming MBW complexes. Our study provides a comprehensive characterization of anthocyanin composition. These findings laid a theoretical foundation for future research on the regulatory mechanisms of pigment accumulation and the breeding of Hippeastrum cultivars with novel petal colors.