Functional Evolution in the Plant SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Family

Abstract

The SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family of transcription factors is functionally diverse, controlling a number of fundamental aspects of plant growth and development, including vegetative phase change, flowering time, branching, and leaf initiation rate. In natural plant populations, variation in flowering time and shoot architecture have major consequences for fitness. Likewise, in crop species, variation in branching and developmental rate impact biomass and yield. Thus, studies aimed at dissecting how the various functions are partitioned among different SPL genes in diverse plant lineages are key to providing insight into the genetic basis of local adaptation and have already garnered attention by crop breeders. Here we use phylogenetic reconstruction to reveal nine major SPL gene lineages, each of which is described in terms of function and diversification. To assess evidence for ancestral and derived functions within each SPL gene lineage, we use ancestral character state reconstructions. Our analyses suggest an emerging pattern of sub-functionalization, neo-functionalization, and possible convergent evolution following both ancient and recent gene duplication. Based on these analyses we suggest future avenues of research that may prove fruitful for elucidating the importance of SPL gene evolution in plant growth and development.

The Juvenile Phase of Maize Sees Upregulation of Stress-Response Genes and Is Extended by Exogenous Jasmonic Acid

“…The Corngrass mutation of maize causes prolonged expression of two of its 12 miR156 loci, thereby extending the juvenile phase (Chuck et al, 2007). The relief of miR156 repression of target transcripts of SQUAMOSA PROMOTER-BINDING (SBP) transcription factors (Preston and Hileman, 2013) confers floral competence by activating the transcription of genes encoding several MADS transcription factors that promote flowering Yamaguchi et al, 2009). SBPs also regulate flowering through the expression of miR172, which targets the transcripts of AP2 transcription factors, some of which inhibit flowering (Zhu and Helliwell, 2011).…”

Characterization of Squamosa Promoter Binding Protein-LIKE genes in wheat

“…The Biological Functions of Wheat SPL Genes SPL genes have been shown to function during various aspects of plant development, as well as during stress responses such as copper tolerance and toxin sensitivity (Preston and Hileman, 2013). In rice, the OsSPL14 and OsSPL16 genes are involved in tiller and spike development, which are closely related to the final grain yield (Jiao et al 2010;.…”

Dual functions of GmTOE4a in the regulation of photoperiod-mediated flowering and plant morphology in soybean

“…In Arabidopsis, among miR156 targets, SPL9 affects plastochron length and leaf size (Schwarz et al 2008;Wang et al 2008), and SPL9 directly promotes the transcription of miR172b (Wu et al 2009). In Glycine max, 45 genes encode SPL proteins (Preston and Hileman 2013). Using the Arabidopsis SPL3 and SPL9 amino acid sequences as queries for a BLAST search, we identified eight GmSPLs in soybean.…”