Molecular cloning and functional analysis of the BplSPL1 gene from Betula platyphylla Suk.

Abstract

BplSPL1 gene was identified in Betula platyphylla Suk, and its sequence features and gene function expression have provided useful information for further studies on function. SQUAMOSA promoter-binding protein-like (SPL) are plant-specific transcription factors that play an important regulatory role in plant growth and development. In this study, an SPL gene, BplSPL1, was cloned from Betula platyphylla Suk. (white birch). Sequence analysis revealed that BplSPL1 has a 405 bp open reading frame (ORF) and encodes a protein of 134 amino acids, which contains a highly conserved SQUAMOSA promoter-binding protein (SBP) domain belonging to the SPL family. Quantitative RT-PCR analysis showed that BplSPL1 was more highly expressed in mature leaf as well as male and female inflorescences. The ectopic expression of BplSPL1 in Arabidopsis led to early flowering, reduced number of rosette leaves, and increased number of lateral branches. We also found that plant height of the transgenic plants decreased, and length of the siliques was shorter in the 35S::BplSPL1 transgenic plants. Further studies showed that the early-flowering phenotype in 35S::BplSPL1 transgenic plants was related to changes in the expression of flowering time genes and flower meristem identity genes, including CUC, FUL, DCL, and SOC1. Therefore, the above results indicate that: (1) BplSPL1 may be involved in regulating flowering time and phase transition, and (2) BplSPL1 may interact with other genes to regulate plant height and the development of lateral branches and fruit.