Plant lateral organ development is a complex process involving both transcriptional activation and repression mechanisms. The We developed a novel Mt Our findings together suggest that transcriptional repression and activation mediated by the
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Summary WOX transcriptional repressorWOX 1/STF , theLEUNIG (LUG ) transcriptional corepressor and theANGUSTIFOLIA 3 (AN 3) transcriptional coactivator play important roles in leaf blade outgrowth and flower development, but how these factors coordinate their activities remains unclear. Here we report physical and genetic interactions among these key regulators of leaf and flower development.in planta transcriptional activation/repression assay and suggest thatLUG could function as a transcriptional coactivator during leaf blade development.LUG physically interacts with MtAN 3, and this interaction appears to be required for leaf and flower development. A single amino acid substitution at position 61 in theSNH domain of MtAN 3 protein abolishes its interaction with MtLUG , and its transactivation activity and biological function. Mutations inlug andan3 enhanced each other's mutant phenotypes. Both thelug and thean3 mutations enhanced thewox1 prs leaf and flower phenotypes inArabidopsis .WOX ,LUG andAN 3 regulators function in concert to promote leaf and flower development, providing novel mechanistic insights into the complex regulation of plant lateral organ development. -
Floral development is one of the model systems for investigating the mechanisms underlying organogenesis in plants. Floral organ identity is controlled by the well-known ABC model, which has been generalized to many flowering plants. Here, we report a previously uncharacterized MYB-like gene,
AGAMOUS-LIKE FLOWER (AGLF ), involved in flower development in the model legumeMedicago truncatula . Loss-of-function ofAGLF results in flowers with stamens and carpel transformed into extra whorls of petals and sepals. Compared with the loss-of-function mutant of the class C geneAGAMOUS (MtAG ) inM. truncatula , the defects in floral organ identity are similar betweenaglf andmtag , but the floral indeterminacy is enhanced in theaglf mutant. Knockout ofAGLF in the mutants of the class A geneMtAP1 or the class B geneMtPI leads to an addition of a loss-of-C-function phenotype, reflecting a conventional relationship ofAGLF with the canonical A and B genes. Furthermore, we demonstrate thatAGLF activatesMtAG in transcriptional levels in control of floral organ identity. These data shed light on the conserved and diverged molecular mechanisms that control flower development and morphology among plant species. -
Abstract silver carp, is an invasive Asian carp that has become increasingly widespread and ecologically destructive within the upper Mississippi River Basin. Its complex trophic anatomy may help explain the apparent efficiency with which they consume phytoplankton, outcompeting native filter feeders. This cypriniform species is characterized by trophic synapomorphies that include a palatal organ, loss of upper pharyngeal jaws, and a hypertrophied lower pharyngeal jaw. However, in silver carp these structures have become greatly modified and diverge from the more basal condition that characterizes species such as goldfish. The trophic apparatus of silver carp is composed of discrete structures that are functionally coupled: filtering plates, paired epibranchial organs (EBO), a modified palatal organ composed of large muscular folds that interdigitate with the filtering plates, and hypertrophied lower pharyngeal jaws and teeth. The filtering plates fill a significant portion of the buccal cavity, especially since the distal parts of these filtering plates make up a key component of the EBOs. EBOs, food aggregating structures found in many teleosts, are thought to have independently evolved at least six times. Ranging in complexity from small slits on the dorsal wall of the pharyngeal cavity to exceedingly intricate spiraling structures, EBOs are morphologically diverse among filter‐feeding fishes. Despite this morphological diversity and broad taxonomic distribution, little is known regarding the functional anatomy of the EBO. Moreover, the EBO in silver carp is distinct from the organs previously described in other species, being created by four independent pharyngeal involutions (instead of the more typical one or two) that form spiral‐shaped pharyngeal tubes surrounded by circumferential muscle. On each side of the head greatly hypertrophied hyomandibulae and opercles are connected to the anterior cartilaginous caps of the bilateral EBOs via enlarged muscles. Given that these fish are pump filter feeders we hypothesize that the opercula may compress and expand the EBOs during pumping causing food to be moved posteriorly toward the pharyngeal jaws.Hypophthalmichthys molitrix , -
Abstract The retrocerebral organ (RCO) is a complex glandular system that is widely distributed across species of phylum Rotifera (sensu stricto). This system is hypothesized to secrete mucus that aids in benthic locomotion, adhesion, and/or reproduction. Unfortunately, the ultrastructure of the RCO is mostly unknown, having only been partially examined in one species. We used transmission electron microscopy and confocal laser scanning microscopy to describe the RCO in the planktonic freshwater rotifer
. Results reveal the RCO to be a singular syncytial organ composed of a posterior glandular region, an expansive reservoir, and an anterior duct. The glandular portion has an active synthetic cytoplasm with paired nuclei, abundant rER, ribosomes, Golgi, and mitochondria. Electron‐dense secretion granules accumulate at the anterior end of the gland and undergo homotypic fusion to create larger, more electron‐lucent granules with numerous mesh‐like contents that gradually fuse into tubular secretions that accumulate in the reservoir. Ultrastructure of these secretions suggests they may be hydrated glycoproteins. Cross‐striated longitudinal muscles form a partial sleeve around the reservoir and may function to squeeze the secretions through the single cytoplasmic duct that penetrates the cerebral ganglion. A review of the RCOs from other rotifers suggests that further ultrastructural analyses are required before attempting to discern their functions and homologies.Trichocerca similis -
SUMMARY Noncoding and coding RNAs are key regulators of plant growth, development, and stress responses. To investigate the types of transcripts accumulated during the vegetative to reproductive transition and floral development in the
Coffea arabica L., we sequenced small RNA libraries from eight developmental stages, up to anthesis. We combined these data with messenger RNA and PARE sequencing of two important development stages that marks the transition of an apparent latent to a rapid growth stage. In addition, we took advantage of multiple in silico tools to characterize genomic loci producing small RNAs such as phasiRNAs, miRNAs, and tRFs. Our differential and co‐expression analysis showed that some types of small RNAs such as tRNAs, snoRNAs, snRNAs, and phasiRNAs preferentially accumulate in a stage‐specific manner. Members of the miR482/miR2118 superfamily and their 21‐nucleotide phasiRNAs originating from resistance genes show a robust co‐expression pattern that is maintained across all the evaluated developmental stages. Finally, the majority of miRNAs accumulate in a family stage‐specific manner, related to modulated hormonal responses and transcription factor expression.