# Overexpression of SlMADS48 Alters the Structure of Inflorescence and the Sizes of Sepal and Fruit in Tomato

## TL;DR

Overexpression of SlMADS48 in tomatoes changes the structure of inflorescence and affects the sizes of sepals and fruits.

## Contribution

This study reveals how SlMADS48 interacts with multiple proteins and regulates gene expression to influence organ size in tomatoes.

## Key findings

- Overexpression of SlMADS48 leads to elongated sepals and increased gibberellin content.
- SlMADS48 interacts with proteins like SlMC, SlMBP21, and SlJOINTLESS involved in sepal development.
- Overexpression reduces fruit size and affects cytokinin and auxin levels.

## Abstract

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.