The Mechanism of MADS-box Gene SlMBP3 Modulating Tomato Fruit Size

MADS-box transcription factors play important role in plant growth and development, especially floral organ identities and fruit development. In our study, a type II MADS-box gene SlMBP3 of Solanum lycopersicum Mill. was isolated. Its tissue-specific expression profile analysis showed that SlMBP3 was highly expressed in reproductive organs such as flower and fruit. Repressed expression of SlMBP3 by RNAi (RNA interference) resulted in fruit developmental-related phenotypes, including reduced fruit size and non-liquefied pectin. Additionally, the seeds of the SlMBP3-RNAi lines displayed severe developmental deficiencies, such as abnormal seed morphology, reduced seed weight, and failed germination. Furthermore, we investigated the morphological, anatomical, and hormonal features of SlMBP3-RNAi transgenic fruits as well as potential molecular mechanisms for the fruit phenotypes. These results suggest that SlMBP3 gene plays important role in regulating tomato fruit and seed development. Understanding the role of SlMBP3 gene will not only extend the biological function of MADS-box genes, but also provide new insight into exploring further regulatory mechanisms of tomato fruit development.