Molecular Characterization of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Family in Betula luminifera

Abstract

As a major family of plant-specific transcription factors, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes play vital regulatory roles in plant growth, development and stress responses. In this study, 18 SPL genes were identified and cloned from Betula luminifera. Two zinc finger-like structures and a nuclear location signal (NLS) segments were existed in the SBP domains of all BlSPLs. Phylogenetic analysis showed that these genes were clustered into nine groups (group I-IX). The intron/exon structure and motif composition were highly conserved within the same group. 12 of the 18 BlSPLs were experimentally verified as the targets of miR156, and two cleavage sites were detected in these miR156-targeted BlSPL genes. Many putative cis-elements, associated with light, stresses and phytohormones response, were identified in the promoter regions of BlSPLs, suggesting that BlSPL genes are probably involved in important physiological processes and developmental events. Tissue-specific expression analysis showed that miR156-targeted BlSPLs exhibited a more differential expression pattern, while most miR156-nontargeted BlSPLs tended to be constitutively expressed, suggesting the distinct roles of miR156-targeted and nontargeted BlSPLs in development and growth of B. luminifera. Further expression analysis revealed that miR156-targeted BlSPLs were dramatically up-regulated with age, whereas mature BlmiR156 level was apparently declined with age, indicating that miR156/SPL module plays important roles in vegetative phase change of B. luminifera. Moreover, yeast two-hybrid assay indicated that several miR156-targeted and nontargeted BlSPLs could interact with two DELLA proteins (BlRGA and BlRGL), which suggests that certain BlSPLs take part in the GA regulated processes through protein interaction with DELLA proteins. All these results provide an important basis for further exploring the biological functions of BlSPLs in B. luminifera.

Genome-wide association mapping reveals novel genes associated with coleoptile length in a worldwide collection of barley

“…The SPL3 protein belongs to SBP family and contains the conserved SBP domain. It is an important plant-specific transcription factor regulating plant growth and development, and the two zinc finger structures are located in the core region of the SBP domain [32]. According to the gene variants, there are four amino acid substitutions, one of which is a serine to alanine change located in the second zinc-finger structure of SBP domain [10].…”

The Role of EjSPL3, EjSPL4, EjSPL5, and EjSPL9 in Regulating Flowering in Loquat (Eriobotrya japonica Lindl.)

“…SBP genes were also found in green plants and referred to as the SQUAMOSA PROMOTER BINDING-LIKE (SPL) genes [18]. In recent decades, the SBP gene families were characterized in model plants, woods, crops, and fruits, such as Arabidopsis thaliana [19], barley [20], green algae [21], moss [22], tomato [23], salvia [24], rice [25], birch [26], light birch [27], cotton [28], grape [29], apple [30], corn [31], and so on. All SPL genes contain a highly conserved DNA binding domain, which was called the SBP-box domain, and it consists of approximately 80 amino acid residues including two zinc finger structures and one nuclear localization signal [32].…”

“…SOC1 also negatively regulates SPL3, SPL4, and SPL5 to form a feedback loop [13]. At present, the functions of SPL genes in more and more species has been unearthed: Grape VpSBP11 can regulate floral transition and leaf development [36]; BlSPLs in Betula luminifera interact with DELLA protein to participate gibberellin regulation [27]. It is reported that, except flowering, SPL genes are vital in also other physiological processes in plants, such as adventitious root development [13,37], fertility [38], fruit growth and quality [39], floral organ and shoot development [40,41], plant hormone response [42], morphological differentiation [43], and stresses response [44].…”

Genome-wide association mapping reveals novel genes associated with coleoptile length in a worldwide collection of barley

“…The SPL3 protein belongs to SBP family and contains the conserved SBP domain. It was an important plant-specific transcription factor regulating plant growth and development, and the two zinc finger structures are located in the core region of the SBP domain [24]. According to the gene variants, there are four amino acid substitutions, one of which is a serine to alanine change located in the second zinc-finger structure of SBP domain [8].…”