MicroProteins are short, single domain proteins that act by sequestering larger, multi-domain proteins into non-functional complexes. MicroProteins have been identified in plants and animals, where they are mostly involved in the regulation of developmental processes. Here we show that two Arabidopsis thaliana microProteins, miP1a and miP1b, physically interact with CONSTANS (CO) a potent regulator of flowering time. The miP1a/b-type microProteins evolved in dicotyledonous plants and have an additional carboxy-terminal PF(V/L)FL motif. This motif enables miP1a/b microProteins to interact with TOPLESS/TOPLESS-RELATED (TPL/TPR) proteins. Interaction of CO with miP1a/b/TPL causes late flowering due to a failure in the induction of FLOWERING LOCUS T (FT) expression under inductive long day conditions. Both miP1a and miP1b are expressed in vascular tissue, where CO and FT are active. Genetically, miP1a/b act upstream of CO thus our findings unravel a novel layer of flowering time regulation via microProtein-inhibition.

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Polyhydroxyalkanoates (PHAs) composed of a mixture of short-chain-length-medium-chainlength (SCL-MCL) hydroxyacyl monomers are biologically produced polyesters that have properties ranging from thermoplastic to elastomeric, dependent on the molar ratio of SCL to MCL monomers incorporated into the copolymer. Because of the potential wide range of properties and applications for SCL-MCL PHA copolymers, it is important to develop and characterize novel metabolic pathways for SCL-MCL PHA production. The current study shows that coexpression of fabG genes from either E. coli or Pseudomonas sp. 61-3 with fabH(F87T) and PHA synthase genes enhances the production of SCL-MCL PHA copolymer from both related and nonrelated carbon sources in Escherichia coli LS5218, indicating the flexibility of FabG as a monomer-supplying enzyme for biological PHA production.

An intricate network of antagonistically acting transcription factors mediates the formation of a flat leaf lamina of Arabidopsis (Arabidopsis thaliana) plants. In this context, members of the class III homeodomain leucine zipper (HD-ZIPIII) transcription factor family specify the adaxial domain (future upper side) of the leaf, while antagonistically acting KANADI transcription factors determine the abaxial domain (future lower side). Here, we used a messenger RNA sequencing approach to identify genes regulated by KANADI1 (KAN1) and subsequently performed a meta-analysis combining our data sets with published genome-wide data sets. Our analysis revealed that KAN1 acts upstream of several genes encoding auxin biosynthetic enzymes. When exposed to shade, we found three YUCCA genes, YUC2, YUC5, and YUC8, to be transcriptionally up-regulated, which correlates with an increase in the levels of free auxin. When ectopically expressed, KAN1 is able to transcriptionally repress these three YUC genes and thereby block shade-induced auxin biosynthesis. Consequently, KAN1 is able to strongly suppress shadeavoidance responses. Taken together, we hypothesize that HD-ZIPIII/KAN form the basis of a basic growth-promoting module. Hypocotyl extension in the shade and outgrowth of new leaves both involve auxin synthesis and signaling, which are under the direct control of HD-ZIPIII/KAN.A fundamental question in plant developmental biology is how plant organs achieve their final form. Leaves of flowering plants are so-called lateral organs that initiate from small populations of founder cells in the periphery of the shoot apical meristem. The initiation and proper spacing of leaves around the shoot apex are mediated by polar auxin transport (Reinhardt et al., 2000(Reinhardt et al., , 2003. Once initiated, polarity axes (proximodistal, dorsoventral, and mediolateral) are established, guiding the fast-dividing primordia cells in order for the leaf to attain its final shape (Hudson, 2000). A complex network of transcription factors and small RNAs acts to divide the leaf primordium along the dorsoventral axis into distinct zones: (1) the adaxial zone producing cells and tissues that will form the upper part of the leaf blade; (2) the abaxial zone that will form the lower side of the leaf blade (Byrne, 2006); and (3) the middle domain required for blade outgrowth (Nakata et al., 2012). It is important to note that, besides the molecular framework that is required for proper leaf initiation and development, the environment strongly influences organ shape and physiology. The latter is exemplified in shade, where the petiole elongates to allow better spacing between the light-capturing leaf blades (Kozuka et al., 2005); increased stomata density in response to elevated CO 2 levels (Woodward, 1987); and decreased leaf size in response to cold temperature (Gurevitch, 1992).