Major latex proteins (MLPs) play a key role in plant response to abiotic and biotic stresses. However, little is known about this gene family in tomatoes (Solanum lycopersicum). In this paper, we perform a genome-wide evolutionary characterization and gene expression analysis of the MLP family in tomatoes. We found a total of 34 SlMLP members in the tomato genome, which are heterogeneously distributed on eight chromosomes. The phylogenetic analysis of the SlMLP family unveiled their evolutionary relationships and possible functions. Furthermore, the tissue-specific expression analysis revealed that the tomato MLP members possess distinct biological functions. Crucially, multiple cis-regulatory elements associated with stress, hormone, light, and growth responses were identified in the promoter regions of these SlMLP genes, suggesting that SlMLPs are potentially involved in plant growth, development, and various stress responses. Subcellular localization demonstrated that SlMLP1, SlMLP3, and SlMLP17 are localized in the cytoplasm. In conclusion, these findings lay a foundation for further dissecting the functions of tomato SlMLP genes and exploring the evolutionary relationships of MLP homologs in different plants.

Rosa roxburghii Tratt., a fruit crop known for its high Vitamin C content and other nutritional compounds, has not yet been studied for its auxin response factor (ARF) family members. ARFs are important proteins in auxin-mediated pathways, playing a vital role in plant physiological and biochemical processes such as plant development, and flower and fruit maturation. In the present study, we identified 14 ARF genes (designated as RrARFs) in R. roxburghii, which are distributed across seven chromosomes and grouped into four subfamilies. An analysis of cis-acting elements revealed that these genes might be involved in various biological processes, including plant development, flower development, light responses, cell cycle regulation, phytohormone responses, and responses to abiotic and biotic stresses. A gene expression analysis demonstrated differential expression of RrARF genes across different tissues and stages of fruit development, with four members showing higher expression during the fruit ripening stages. Furthermore, a coexpression analysis identified that RrARF5 was highly coexpressed with RrMDHAR1, a key enzyme involved in Vitamin C biosynthesis. Moreover, transactivation assays and transient overexpression experiments confirmed that RrARF5 activates the transcription of RrMDHAR1. The findings of this study suggest a potential role of the ARF gene family in Vitamin C accumulation in R. roxburghii and enhance our understanding of the diverse regulatory function of the ARF gene family in plants.

Rosa roxburghii Tratt., a fruit crop known for its high vitamin C content and other nutritional compounds, has not yet been studied for its Auxin Responsive Factor (ARF) gene family, which plays a crucial role in plant growth and fruit development. In the present study, we identified 14 ARF genes (designated as RrARFs) in R. roxburghii, which are distributed across seven chromosomes and grouped into four subfamilies. Cis-acting elements analyses revealed that these genes might be involved in various biological processes, including plant development, light responses, cell cycle regulation, phytohormone responses, and responses to abiotic and biotic stresses. Gene expression analysis demonstrated differential expression of RrARF genes across different tissues and stages of fruit development, with four members showing higher expression during the fruit ripening stages. Furthermore, coexpression analysis identified that RrARF5 was highly coexpressed with RrMDHAR1, a key enzyme involved in vitamin C biosynthesis. Moreover, transactivation assays and transient overexpression experiments confirmed that RrARF5 activates the transcription of RrMDHAR1. The outcomes of this study enhance our understanding of the ARF gene family's role in vitamin C accumulation in R. roxburghii and its broader impact on fruit quality regulation.