Molecular characterization and expression analysis of Triticum aestivum squamosa-promoter binding protein-box genes involved in ear development

Wheat （Triticum aestivum L.） is one of the most important crops in the world. Squamosa-promoter binding protein （SBP）-box genes play a critical role in regulating flower and fruit development. In this study, 10 novel SBP-box genes （TaSPL genes） were isolated from wheat （（Triticum aestivum L.） cultivar Yanzhan 4110）. Phylogenetic analysis classified the TaSPL genes into five groups （G1-G5）. The motif combinations and expression patterns of the TaSPL genes varied among the five groups with each having own distinctive characteristics： TaSPL20/21 in G1 and TaSPL17 in G2 mainly expressed in the shoot apical meristem and the young ear, and their expression levels responded to development of the ear; TaSPL6/15 belonging to G3 were upregulated and TaSPL1/23 in G4 were downregulated during grain development; the gene in G5 （TaSPL3） expressed constitutively. Thus, the consistency of the phylogenetic analysis, motif compositions, and expression patterns of the TaSPL genes revealed specific gene structures and functions. On the other hand, the diverse gene structures and different expression patterns suggested that wheat SBP-box genes have a wide range of functions. The results also suggest a potential role for wheat SBP-box genes in ear development. This study provides a significant beginning of functional analysis of SBP-box genes in wheat.

Complex regulatory network of Betula BplSPL8 in planta

SQUAMOSA-promoter binding protein-like (SPL) proteins are plant-specific transcription factors and participate in different pathways, including the vegetative to reproductive transition, male sterility, biosynthesis of gibberellic acid (GA), plant morphogenesis and response to environmental stress. In this study, we generated transgenic Arabidopsis that overexpressed Betula BplSPL8 and confirmed that BplSPL8 is a transcription factor with transcriptional activation activity and is located in the nucleus. Functional analysis of BplSPL8 showed that it is involved in regulating different development processes: (1) BplSPL8 can delay flowering by reducing sensitivity to GA under short days; (2) BplSPL8 controls the number and morphogenesis of leaves, including up-rolling leaves under long days and folded leaves mediated by GA under short days; (3) BplSPL8 can promote root elongation during late development of roots and inhibit lateral root formation; (4) BplSPL8 may be involved in regulating carotenoid biosynthesis and secretion metabolism. These results show that there is a complex regulatory network for the SPL family genes that is mediated by other components and may provide a new insights for the functional research of SPL genes.

The miR156/SPL Module, a Regulatory Hub and Versatile Toolbox, Gears up Crops for Enhanced Agronomic Traits

In the past two decades, members of the SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE （SPL） family of transcription factors, first identified in Antirrhinum majus, have emerged as pivotal regulators of diverse biological processes in plants, including the timing of vegetative and reproductive phase change, leaf development, tillering/branching, plastochron, panicle/tassel architecture, fruit ripening, fertility, and response to stresses. Transcripts of a subset of SPLs are targeted for cleavage and/or translational repres- sion by microRNA156s （miR156s）. The levels of miR156s are regulated by both endogenous developmental cues and various external stimuli. Accumulating evidence shows that the regulatory circuit around the miR156/SPL module is highly conserved among phylogenetically distinct plant species, and plays impor- tant roles in regulating plant fitness, biomass, and yield. With the expanding knowledge and a mechanistic understanding of their roles and regulatory relationship, we can now harness the miR156/SPL module as a plethora of tools to genetically manipulate crops for optimal parameters in growth and development, and ultimately to maximize yield by intelligent design of crops.