Abstract
MADS-box genes play a pivotal role in various processes, including floral and seed development, controlling flowering time, regulation of fruits ripening, and respond to abiotic and biotic stressors in planta. Tobacco (Nicotiana tabacum) has been widely used as a model plant for analyzing the gene function, however, there has been less information on the regulation of flowering, and the associated genes. In the present study, a total of 168 NtMADS-box genes were identified from tobacco, and their phylogenetic relationship, chromosome locations, and gene structures were further analyzed. NtMADS-box genes can be clustered into four sub-families of Mα, Mγ, MIKC*, and MIKCC. A total of 111 NtMADS-box genes were distributed on 20 chromosomes, and 57 NtMADS-box genes were located on the unanchored scaffolds due to the complex and incomplete assembly of the tobacco genome. Expression profiles of NtMADS-box genes by microarray from 23 different tissues indicated that members in different NtMADS-box gene subfamilies might play specific roles in the growth and flower development, and the transcript levels of 24 NtMADS-box genes were confirmed by quantitative real-time PCR. Importantly, overexpressed NtSOC1/NtMADS133 could promote early flowering and dwarfism in transgenic tobacco plants. Therefore, our findings provide insights on the characterization of NtMADS-box genes to further study their functions in plant development.
Highlights
The MADS-box gene family represents an important type of transcription factors, which is widely present in fungi, animals, and plants [1]
Local BLAST and HMM analyses based on the China Tobacco Genome Database (N. tabacum) were performed, and genes such as pseudogenes, premature stop codons genes, or without complete MADS domain were removed
Phylogenetic and gene structure analysis revealed that NtMADS-box can be divided into two types, type I and type II, and clustered into four sub-families of Mα, Mγ, MIKC*, and MIKCC
Summary
The MADS-box gene family represents an important type of transcription factors, which is widely present in fungi, animals, and plants [1]. All the MADS-box proteins contain a conservative MADS domain at the N terminus consisting of 58–60 amino acid residues [6], and encode a transcription factor which can bind to the CArG box (CC-A-rich-GC) in the promoter region of their target genes [7]. The type I MADS-box genes contain an SRF domain that exists in both plants and animals [9], while type II MADS-box genes encode MEF2-like proteins and MIKC-type proteins [9]. Based on the differences in gene structures, the type I MADS-box genes can be divided into three subfamilies (Mα, Mβ, and Mγ), while type II MADS-box genes can be divided into MIKCC and MIKC* types [11]. Limited studies have focused on the function of type I MADS-box genes [13]
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