Comparative analysis of the SBP-box gene families in P. patens and seed plants

Abstract

To come to a better understanding of the evolution and function of the SBP-box transcription factor family in plants, we identified, isolated and characterized 13 of its members from the moss Physcomitrella patens. For the majority of the moss SBP-box genes, clear orthologous relationships with family members of flowering plants could be established by phylogenetic analysis based on the conserved DNA-binding SBPdomain, as well as additional synapomorphic molecular characters. The P. patens SBP-box genes cluster in four separable groups. One of these consists exclusively of moss genes; the three others are shared with family members of Arabidopsis and rice. Besides the family defining DNAbinding SBP-domain, other features can be found conserved between moss and other plant SBP-domain proteins. An AHA-like motif conserved from the unicellular alga Chlamydomonas reinhardtii to flowering plants, was found able to promote transcription in a heterologous yeast system. The conservation of a functional microRNA response element in the mRNA of three of the moss SBP-box genes supports the idea of an ancient origin of microRNA dependent regulation of SBP-box gene family members.As our current knowledge concerning the roles of SBP-box genes in plant development is scarce and the model system P. patens allows targeted mutation, the material we isolated and characterized will be helpful to generate the mutant phenotypes necessary to further elucidate these roles.

ThemicroRNA156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE3Module Regulates Ambient Temperature-Responsive Flowering viaFLOWERING LOCUS Tin Arabidopsis

“…Vernalization is distinct from other temperature-dependent flowering responses in that it is controlled by a pathway that requires FLOWERING LOCUS C, which appears to be crucifer specific (Amasino and Michaels, 2010). However, in evolutionary terms, miR156 is a highly conserved miRNA, and its interaction with SQUAMOSA PROMOTER BINDING PROTEIN box genes has an ancient origin in land plants (Arazi et al, 2005;Riese et al, 2007;Willmann and Poethig, 2007;Guo et al, 2008;Wu et al, 2009;Gou et al, 2011). Thus, it is possible that the miR156-SPL3-FT genetic circuitry functions in a diverse array of flowering plants.…”

The control of developmental phase transitions in plants

“…The analysis of specific targets or groups of targets informed by phylogeny and, in particular, paralogous relationships (Guo et al, 2008;Riese et al, 2007;Xie et al, 2006), has helped to unveil their respective roles in developmental phase transitions.…”

Transcriptional control of flavonoid biosynthesis

“…20 The first group comprises only 5 members (SPL1, SPL7, SPL12, SPL14, and SPL16) and the remaining 12 SPL proteins fall into the second group. With the exception of SPL8, all members of the second group are targeted by miR156/157 for posttranscriptional regulation.…”

“…With the exception of SPL8, all members of the second group are targeted by miR156/157 for posttranscriptional regulation. 20,21 These plantspecific SPB-box proteins are known to influence a large array of developmental processes in Arabidopsis, such as promoting the juvenile-to-adult phase transition by activating miR172, inducing flowering via activating LEAFY and the MADS box genes, inhibiting trichome initiation on floral organs through activating TCL1, as well as concertedly controlling male fertility. [21][22][23][24] Recently, the miR156/157-targeted SPLs have been shown to affect metabolic fluxes through the branched flavonoid biosynthetic pathway.…”