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2.
J Exp Bot ; 75(11): 3220-3232, 2024 Jun 07.
Article in English | MEDLINE | ID: mdl-38527334

ABSTRACT

The first TALE homeodomain transcription factor gene to be described in plants was maize knotted1 (kn1). Dominant mutations in kn1 disrupt leaf development, with abnormal knots of tissue forming in the leaf blade. kn1 was found to be expressed in the shoot meristem but not in a peripheral region that gives rise to leaves. Furthermore, KN1 and closely related proteins were excluded from initiating and developing leaves. These findings were a prelude to a large body of work wherein TALE homeodomain proteins have been identified as vital regulators of meristem homeostasis and organ development in plants. KN1 homologues are widely represented across land plant taxa. Thus, studying the regulation and mechanistic action of this gene class has allowed investigations into the evolution of diverse plant morphologies. This review will focus on the function of TALE homeodomain transcription factors in leaf development in eudicots. Here, we discuss how TALE homeodomain proteins contribute to a spectrum of leaf forms, from the simple leaves of Arabidopsis thaliana to the compound leaves of Cardamine hirsuta and species beyond the Brassicaceae.


Subject(s)
Homeodomain Proteins , Plant Leaves , Plant Proteins , Transcription Factors , Plant Leaves/metabolism , Plant Leaves/growth & development , Plant Leaves/genetics , Homeodomain Proteins/metabolism , Homeodomain Proteins/genetics , Transcription Factors/metabolism , Transcription Factors/genetics , Plant Proteins/metabolism , Plant Proteins/genetics , Gene Expression Regulation, Plant , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis/growth & development , Meristem/genetics , Meristem/growth & development , Meristem/metabolism
3.
Curr Biol ; 32(17): R912-R914, 2022 09 12.
Article in English | MEDLINE | ID: mdl-36099893

ABSTRACT

Leaves come in a wide variety of shapes, from simple to lobed to dissected. A new study suggests this variation is determined by a preferred evolutionary genetic pathway that modifies shape by regulating regional growth in the developing leaf.


Subject(s)
Biological Evolution , Plant Leaves
4.
J Exp Bot ; 72(5): 1738-1747, 2021 02 27.
Article in English | MEDLINE | ID: mdl-33247922

ABSTRACT

Plant leaves are the main photosynthetic organ of plants and they occur in an array of different shapes. Leaf shape is determined by morphogenesis whereby patterning of the leaf margin can result in interspaced leaf serrations, lobes, or leaflets, depending on the species, developmental stage, and in some instances the environment. In Arabidopsis, mutations in the homeodomain transcription factors SAW1 and SAW2 result in more prominent leaf margin serrations. Here we show that serrations appear precociously in the saw1 saw2 mutant. The pattern of auxin maxima, and of PIN1 and CUC2 expression, which form a feedback loop that drives serration outgrowth, is altered in saw1 saw2 and correlates with precocious serration initiation. SAW1 is not expressed in the outer epidermal cell layer where PIN1 convergence points generate auxin maxima. Instead, SAW1 is expressed on the adaxial side of the leaf and expression in this domain is sufficient for function. We suggest that SAW1 and SAW2 repress serration initiation and outgrowth by promoting the transition to a determinate fate in the leaf margin.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Homeodomain Proteins/metabolism , Plant Leaves/anatomy & histology , Transcription Factors/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Gene Expression Regulation, Plant , Homeodomain Proteins/genetics , Indoleacetic Acids , Mutation , Transcription Factors/genetics
5.
Curr Opin Plant Biol ; 53: 73-79, 2020 02.
Article in English | MEDLINE | ID: mdl-31785585

ABSTRACT

Plants continuously produce lateral organs from the shoot apex such as leaves and flowers, providing an excellent opportunity to study their development. The plant hormone auxin plays a central role in this process by promoting organ formation where it accumulates due to polar auxin transport. Recently, the use of live-imaging, fine perturbation techniques and computational modelling has helped researchers make exciting progress in addressing long-standing questions on plant organogenesis, not only regarding the role of auxin in promoting growth but also on the regulation of morphogenesis and transcriptional control. In this review, we discuss a number of recent studies that address these points, with particular reference to how auxin acts in early leaf development and in leaf shape.


Subject(s)
Arabidopsis , Indoleacetic Acids , Flowers , Gene Expression Regulation, Plant , Meristem , Plant Growth Regulators , Plant Leaves
6.
New Phytol ; 217(4): 1654-1666, 2018 03.
Article in English | MEDLINE | ID: mdl-29341123

ABSTRACT

Mutants without root hairs show reduced inorganic orthophosphate (Pi) uptake and compromised growth on soils when Pi availability is restricted. What is less clear is whether root hairs that are longer than wild-type provide an additional benefit to phosphorus (P) nutrition. This was tested using transgenic Brachypodium lines with longer root hairs. The lines were transformed with the endogenous BdRSL2 and BdRSL3 genes using either a constitutive promoter or a root hair-specific promoter. Plants were grown for 32 d in soil amended with various Pi concentrations. Plant biomass and P uptake were measured and genotypes were compared on the basis of critical Pi values and P uptake per unit root length. Ectopic expression of RSL2 and RSL3 increased root hair length three-fold but decreased plant biomass. Constitutive expression of BdRSL2, but not expression of BdRSL3, consistently improved P nutrition as measured by lowering the critical Pi values and increasing Pi uptake per unit root length. Increasing root hair length through breeding or biotechnology can improve P uptake efficiency if the pleotropic effects on plant biomass are avoided. Long root hairs, alone, appear to be insufficient to improve Pi uptake and need to be combined with other traits to benefit P nutrition.


Subject(s)
Brachypodium/genetics , Gene Expression Regulation, Plant , Genes, Plant , Models, Biological , Phosphorus/metabolism , Plant Roots/anatomy & histology , Biomass , Brachypodium/drug effects , Brachypodium/growth & development , Gene Expression Regulation, Plant/drug effects , Genotype , Mycorrhizae/drug effects , Mycorrhizae/physiology , Phosphorus/pharmacology , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Roots/drug effects , Plant Roots/growth & development , Plants, Genetically Modified
7.
Front Plant Sci ; 6: 1102, 2015.
Article in English | MEDLINE | ID: mdl-26734020

ABSTRACT

The ribosome in higher eukaryotes is a large macromolecular complex composed of four rRNAs and eighty different ribosomal proteins. In plants, each ribosomal protein is encoded by multiple genes. Duplicate genes within a family are often necessary to provide a threshold dose of a ribosomal protein but in some instances appear to have non-redundant functions. Here, we addressed whether divergent members of the RPL9 gene family are dosage sensitive or whether these genes have non-overlapping functions. The RPL9 family in Arabidopsis thaliana comprises two nearly identical members, RPL9B and RPL9C, and a more divergent member, RPL9D. Mutations in RPL9C and RPL9D genes lead to delayed growth early in development, and loss of both genes is embryo lethal, indicating that these are dosage-sensitive and redundant genes. Phylogenetic analysis of RPL9 as well as RPL4, RPL5, RPL27a, RPL36a, and RPS6 family genes in the Brassicaceae indicated that multicopy ribosomal protein genes have been largely retained following whole genome duplication. However, these gene families also show instances of tandem duplication, small scale deletion, and evidence of gene conversion. Furthermore, phylogenetic analysis of RPL9 genes in angiosperm species showed that genes within a species are more closely related to each other than to RPL9 genes in other species, suggesting ribosomal protein genes undergo convergent evolution. Our analysis indicates that ribosomal protein gene retention following whole genome duplication contributes to the number of genes in a family. However, small scale rearrangements influence copy number and likely drive concerted evolution of these dosage-sensitive genes.

8.
Plant Physiol ; 165(3): 1133-1143, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24872379

ABSTRACT

Ribosomal protein mutations in Arabidopsis (Arabidopsis thaliana) result in a range of specific developmental phenotypes. Why ribosomal protein mutants have specific phenotypes is not fully known, but such defects potentially result from ribosome insufficiency, ribosome heterogeneity, or extraribosomal functions of ribosomal proteins. Here, we report that ovule development is sensitive to the level of Ribosomal Protein L27a (RPL27a) and is disrupted by mutations in the two paralogs RPL27aC and RPL27aB. Mutations in RPL27aC result in high levels of female sterility, whereas mutations in RPL27aB have a significant but lesser effect on fertility. Progressive reduction in RPL27a function results in increasing sterility, indicating a dose-dependent relationship between RPL27a and female fertility. RPL27a levels in both the sporophyte and gametophyte affect female gametogenesis, with different developmental outcomes determined by the dose of RPL27a. These results demonstrate that RPL27aC and RPL27aB act redundantly and reveal a function for RPL27a in coordinating complex interactions between sporophyte and gametophyte during ovule development.

9.
Plant Physiol ; 161(3): 1291-302, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23355632

ABSTRACT

Grasses produce florets on a structure called a spikelet, and variation in the number and arrangement of both branches and spikelets contributes to the great diversity of grass inflorescence architecture. In Brachypodium (Brachypodium distachyon), the inflorescence is an unbranched spike with a terminal spikelet and a limited number of lateral spikelets. Spikelets are indeterminate and give rise to a variable number of florets. Here, we provide a detailed description of the stages of inflorescence development in Brachypodium. To gain insight into the genetic regulation of Brachypodium inflorescence development, we generated fast neutron mutant populations and screened for phenotypic mutants. Among the mutants identified, the more spikelets1 (mos1) mutant had an increased number of axillary meristems produced from inflorescence meristem compared with the wild type. These axillary meristems developed as branches with production of higher order spikelets. Using a candidate gene approach, mos1 was found to have a genomic rearrangement disrupting the expression of an ethylene response factor class of APETALA2 transcription factor related to the spikelet meristem identity genes branched silkless1 (bd1) in maize (Zea mays) and FRIZZY PANICLE (FZP) in rice (Oryza sativa). We propose MOS1 likely corresponds to the Brachypodium bd1 and FZP ortholog and that the function of this gene in determining spikelet meristem fate is conserved with distantly related grass species. However, MOS1 also appears to be involved in the timing of initiation of the terminal spikelet. As such, MOS1 may regulate the transition to terminal spikelet development in other closely related and agriculturally important species, particularly wheat (Triticum aestivum).


Subject(s)
Brachypodium/growth & development , Inflorescence/growth & development , Plant Proteins/metabolism , Amino Acid Sequence , Base Sequence , Brachypodium/ultrastructure , Chromosomes, Plant/metabolism , Gene Rearrangement/genetics , Genes, Plant/genetics , Inflorescence/ultrastructure , Molecular Sequence Data , Mutagenesis/genetics , Mutation/genetics , Plant Proteins/chemistry , Plant Proteins/genetics , Reproduction , Transcription Factors/metabolism
10.
J Plant Res ; 126(1): 3-15, 2013 Jan.
Article in English | MEDLINE | ID: mdl-22922868

ABSTRACT

In recent years, an increasing number of mutations in what would appear to be 'housekeeping genes' have been identified as having unexpectedly specific defects in multicellular organogenesis. This is also the case for organogenesis in seed plants. Although it is not surprising that loss-of-function mutations in 'housekeeping' genes result in lethality or growth retardation, it is surprising when (1) the mutant phenotype results from the loss of function of a 'housekeeping' gene and (2) the mutant phenotype is specific. In this review, by defining housekeeping genes as those encoding proteins that work in basic metabolic and cellular functions, we discuss unexpected links between housekeeping genes and specific developmental processes. In a surprising number of cases housekeeping genes coding for enzymes or proteins with functions in basic cellular processes such as transcription, post-transcriptional modification, and translation affect plant development.


Subject(s)
Genes, Plant , Organogenesis/genetics , Plant Structures/cytology , Plant Structures/embryology , Cell Differentiation/genetics , Cell Differentiation/physiology , Gene Expression Regulation, Plant , Genes, Essential , Mutation , Organogenesis/physiology , Phenotype , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Structures/genetics , Plant Structures/growth & development , Transcription, Genetic
11.
J Exp Bot ; 63(14): 5233-43, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22791832

ABSTRACT

Leaves develop as planar organs, with a morphology that is specialized for photosynthesis. Development of a planar leaf requires genetic networks that set up opposing adaxial and abaxial sides of the leaf, which leads to establishment of dorsoventral polarity. While many genes have been identified that regulate adaxial and abaxial fate there is little information on how this is integrated with cellular function. EMBRYO DEFECTIVE DEVELOPMENT1 (EDD1) is a nuclear gene that encodes a plastid and mitochondrial localized glycyl-tRNA synthetase. Plants with partial loss of EDD1 function have changes in patterning of margin and distal regions of the leaf. In combination with mutations in the MYB domain transcription factor gene ASYMMETRIC LEAVES1 (AS1), partial loss of EDD1 function results in leaves with reduced adaxial fate. EDD1 may influence leaf dorsoventral polarity through regulating the abaxial fate genes KANADI1 (KAN1) and ETTIN (ETT)/AUXIN RESPONSE FACTOR3 (ARF3) since these genes are upregulated in the edd1 as1 double mutant. SCABRA3 (SCA3), a nuclear gene that encodes the plastid RNA polymerase is also required for leaf adaxial fate in the absence of AS1. These results add a novel component to networks of genetic regulation of leaf development and suggest that organelles, particularly plastids, are required in leaf patterning. Potentially, signalling from organelles is essential for coordination of different cell fates within the developing leaf.


Subject(s)
Amino Acyl-tRNA Synthetases/genetics , Arabidopsis Proteins/genetics , Arabidopsis/genetics , Gene Expression Regulation, Plant , Plant Leaves/growth & development , Transcription Factors/genetics , Amino Acyl-tRNA Synthetases/metabolism , Arabidopsis/growth & development , Arabidopsis Proteins/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Developmental , Glycine-tRNA Ligase/genetics , Glycine-tRNA Ligase/metabolism , Mitochondria/metabolism , Mutation , Nuclear Proteins/metabolism , Plastids/metabolism , Transcription Factors/metabolism
12.
Curr Opin Plant Biol ; 15(1): 24-30, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22079784

ABSTRACT

Leaves are determinate organs that develop from the flanks of the shoot apical meristem through founder cell recruitment, establishment of proximodistal, dorsoventral and mediolateral axes, and subsequent growth, expansion and differentiation along these axes. Maintenance of the shoot apical meristem and production of leaves requires balanced partitioning of cells between pluripotent and differentiation fates. Hormones have a significant role in this balance but it is becoming apparent that additional intrinsic and extrinsic inputs influence hormone signalling to control meristem function and leaf initiation. As leaves develop, temporal and spatial regulation of growth and maturation determines leaf shape and complexity. Remarkably genes involved in leaf development in the context of the shoot apical meristem are also involved in elaboration of the leaf shape to generate subtle marginal serrations, more prominent lobes or a dissected compound leaf. Potentially these common regulatory modules represent a fundamental means of setting up boundaries separating discrete zones of growth. Defining gene networks involved in leaf shape variation and exploring interspecies differences between such networks is enabling exciting insight into changes that contribute to natural variation of leaf form.


Subject(s)
Plant Leaves/growth & development , Body Patterning , Models, Biological , Plant Leaves/anatomy & histology
13.
Plant Signal Behav ; 6(5): 712-4, 2011 May.
Article in English | MEDLINE | ID: mdl-21448008

ABSTRACT

The plant shoot apical meristem is established early during embryogenesis and subsequently gives rise to a shoot through reiterative generation of lateral organs and axillary meristems. In our recent manuscript we reported identification and characterization of a semi-dominant mutation in ribosomal protein RPL27a, which disrupts plant growth and shoot development.1 rpl27ac-1d effects on the shoot are evident from an early stage of embryo development. During embryogenesis rpl27-1d mutants are slow growing and are defective in apical patterning with a delay in establishment of the shoot meristem and outgrowth of cotyledons. Concomitant with this disturbed patterning, the shoot meristem genes SHOOT MERISTEMLESS (STM) and CUP-SHAPED COTYLEDON2 (CUC2) are misexpressed in outer cell layers of the rpl27ac-1d embryo and there is a delay in expression of the organ-patterning gene FILAMENTOUS FLOWER (FIL). Genetic interactions between rpl27ac-1d and other ribosomal protein mutants indicates rpl27ac-1d has reduced ribosome function. Our results highlight a role for ribosomal proteins in growth and development and we propose that the ribosome regulates specific patterning events during development.


Subject(s)
Arabidopsis/embryology , Arabidopsis/metabolism , Meristem/embryology , Meristem/metabolism , Ribosomal Proteins/metabolism , Arabidopsis/ultrastructure , Body Patterning , Inflorescence/embryology , Inflorescence/ultrastructure , Meristem/ultrastructure , Organogenesis , Phenotype
14.
Plant J ; 65(2): 269-81, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21223391

ABSTRACT

Ribosomal proteins are integral to ribosome biogenesis, and function in protein synthesis. In higher eukaryotes, loss of cytoplasmic ribosomal proteins results in a reduced growth rate as well as developmental defects. To what extent and how ribosomal proteins affect development is currently not known. Here we describe a semi-dominant mutation in the cytoplasmic ribosomal protein gene RPL27aC that affects multiple aspects of plant shoot development, including leaf patterning, inflorescence and floral meristem function, and seed set. In the embryo, RPL27aC is required to maintain the growth rate and for the transition from radial to bilateral symmetry associated with initiation of cotyledons. rpl27ac-1d embryos undergo stereotypical patterning to establish a globular embryo. However, a temporal delay in initiation and outgrowth of cotyledon primordia leads to development of an enlarged globular embryo prior to apical domain patterning. Defects in embryo development are coincident with tissue-specific ectopic expression of the shoot meristem genes SHOOT MERISTEMLESS (STM) and CUP-SHAPED COTYLEDON2 (CUC2), in addition to delayed expression of the abaxial gene FILAMENTOUS FLOWER (FIL) and mis-regulation of the auxin efflux effector PIN-FORMED1 (PIN1). Genetic interactions with other ribosomal protein mutants indicate that RPL27aC is a component of the ribosome. We propose that RPL27aC regulates discrete developmental events by controlling spatial and temporal expression of developmental patterning genes via an as yet undefined process involving the ribosome.


Subject(s)
Arabidopsis/growth & development , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Meristem/growth & development , Ribosomal Proteins/physiology , Arabidopsis/embryology , Arabidopsis/genetics , Arabidopsis/physiology , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Body Patterning , Cotyledon/genetics , Cotyledon/growth & development , Indoleacetic Acids/metabolism , Meristem/genetics , Mutagenesis, Insertional , Phenotype , Plants, Genetically Modified , Ribosomal Proteins/genetics , Transcription Factors/genetics , Transcription Factors/metabolism
15.
J Plant Res ; 123(3): 281-90, 2010 May.
Article in English | MEDLINE | ID: mdl-20369373

ABSTRACT

Leaves occur in a vast array of shapes and sizes, with complex diversity contributing to optimization of the principal function of photosynthesis. The program of development from a self-renewing stem cell population to a mature leaf has been of interest to biologists for years. Many genes involved in this process have been identified, particularly in the model eudicot Arabidopsis, so that now we have a greater understanding of mechanisms of stem cell maintenance, cell differentiation and organogenesis. One aspect of leaf development that is of particular interest is the establishment of dorsoventral polarity: the distinct adaxial (upper) and abaxial (lower) sides of the leaf. Early studies postulated conceptual models of how establishment of polarity leads to the development of planar leaves. Studies over the past decade have defined genetic details of this model, and uncovered diverse mechanisms of gene regulation that facilitate development of leaf dorsoventral polarity, including transcriptional regulation, chromatin modification, DNA modification, regulation by short RNAs and translational and post-translational regulation. This review will discuss these regulatory mechanisms in the context of leaf dorsoventrality, and will conclude with unresolved questions and areas of future research.


Subject(s)
Body Patterning , Cell Polarity , Plant Leaves/cytology , Plant Leaves/embryology , Plant Leaves/genetics , Plant Proteins/genetics , Plant Proteins/metabolism , RNA Stability/genetics , Trans-Activators/metabolism
16.
Trends Plant Sci ; 14(9): 512-9, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19716746

ABSTRACT

Development of a multicellular organism involves coordinated cell division, growth and specialization to generate different cell types that contribute to organized tissues, distinct organs and a higher order body plan. This coordinated process requires tight regulation of gene expression, which is mediated by multiple transcriptional, post-transcriptional, translational and post-translational control mechanisms. As I discuss here, recent studies on ribosomal protein genes and ribosome assembly genes indicate that the basic translational machinery of the cell, the ribosome, has a regulatory role in plant development. A comparison between plants and animals reveals both divergent trends in the genome content of ribosomal proteins and intriguing potential overlaps in the role of the ribosome in development.


Subject(s)
Arabidopsis/growth & development , Arabidopsis/metabolism , Ribosomes/metabolism , Animals , Arabidopsis/genetics , Eukaryotic Cells/metabolism , Mutation/genetics , Phenotype , Ribosomal Proteins/genetics , Ribosomal Proteins/metabolism
17.
J Steroid Biochem Mol Biol ; 112(1-3): 122-6, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18840526

ABSTRACT

High vitamin D intake is associated with reduced insulin resistance. Expression of extra-renal 1alpha,25-dihydroxyvitamin D hydroxylase (1alpha-hydroxylase) has been reported in several tissues and contributes to local synthesis of 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D) from the substrate 25-hydroxyvitamin D (25OHD). Expression and dietary regulation of 1alpha-hydroxylase in tissues associated with energy metabolism, including adipose tissue, has not been assessed. Male Wistar rats were fed a high calcium (1.5%) and high vitamin D (10,000IU/kg) or a low calcium (0.25%), low vitamin D (400IU/kg) with either a high fat (40% energy) or high sucrose (66% energy) dietary background for 14 weeks. Expression of 1alpha-hydroxylase, assessed by real time PCR, was detected in adipose tissue and did not differ with dietary level of calcium and vitamin D. 1alpha-Hydroxylase mRNA was also detected in 3T3-L1 preadipocytes and 25OHD treatment at 10nM levels induced 1,25(OH)(2)D responsive gene, CYP24, and this response was reduced in the presence of the p450 inhibitor, ketoconazole. In addition, (3)H 25OHD was converted to (3)H 1,25(OH)(2)D in intact 3T3-L1 preadipocytes. Cumulatively, these results demonstrate that 1alpha-hydroxylase is expressed in adipose tissue and is functional in cultured adipocytes. Thus, the capacity for local production may play a role in regulating adipocyte growth and metabolism.


Subject(s)
25-Hydroxyvitamin D3 1-alpha-Hydroxylase/metabolism , Adipocytes/enzymology , Adipose Tissue/enzymology , RNA, Messenger/metabolism , 3T3-L1 Cells , Animals , Calcium/administration & dosage , Diet , Ketoconazole/pharmacology , Male , Mice , Rats , Rats, Wistar , Steroid Hydroxylases/antagonists & inhibitors , Steroid Hydroxylases/metabolism , Vitamin D/administration & dosage , Vitamin D/analogs & derivatives , Vitamin D3 24-Hydroxylase , Vitamins/administration & dosage
18.
Proc Natl Acad Sci U S A ; 105(35): 12915-20, 2008 Sep 02.
Article in English | MEDLINE | ID: mdl-18725639

ABSTRACT

Transition from the vegetative phase to reproductive phase is a crucial process in the life cycle of higher plants. Although the molecular mechanisms of flowering regulation have been extensively characterized in a number of plant species, little is known regarding how the transition process initiates. Here, we show that the Rice Indeterminate 1 (RID1) gene acts as the master switch for the transition from the vegetative to reproductive phase. RID1 encodes a Cys-2/His-2-type zinc finger transcription factor that does not have an ortholog in Arabidopsis spp. A RID1 knockout (rid1), mutated by T-DNA insertion, never headed after growing for >500 days under a range of growth conditions and is thus referred to as a never-flowering phenotype. This mutation-suppressed expression of the genes is known to be involved in flowering regulation, especially in the Ehd1/Hd3a pathway and a series of RFT homologs. RID1 seems to be independent of the circadian clock. A model was proposed to place RID1 in the molecular pathways of flowering regulation in rice, for which there are two indispensable elements. In the first, RID1 is controlling the phase transition and initiation of floral induction. In the other, the Hd3a/RFL1/FTL complex acts as the immediate inducer of flowering. Loss of function in either element would cause never-flowering. Once the phase transition is induced with the activation of RID1, flowering signal is transduced and regulated through the various pathways and eventually integrated with FT-like proteins to induce flowering.


Subject(s)
Flowers/embryology , Genes, Switch , Oryza/embryology , Oryza/genetics , Plant Proteins/metabolism , Transcription Factors/metabolism , Zinc Fingers , Amino Acid Sequence , Biological Clocks , Circadian Rhythm , Flowers/genetics , Gene Expression Regulation, Plant , Genes, Plant , Genes, Reporter , Genetic Complementation Test , Glucuronidase/metabolism , Green Fluorescent Proteins/metabolism , Models, Genetic , Molecular Sequence Data , Mutation/genetics , Phenotype , Plant Proteins/chemistry , Plant Proteins/genetics , Subcellular Fractions/metabolism , Transcription Factors/genetics
19.
Development ; 135(7): 1315-24, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18305008

ABSTRACT

Leaves are determinate organs that arise from the flanks of the shoot apical meristem as polar structures with distinct adaxial (dorsal) and abaxial (ventral) sides. Opposing regulatory interactions between genes specifying adaxial or abaxial fates function to maintain dorsoventral polarity. One component of this regulatory network is the Myb-domain transcription factor gene ASYMMETRIC LEAVES1 (AS1). The contribution of AS1 to leaf polarity varies across different plant species; however, in Arabidopsis, as1 mutants have only mild defects in leaf polarity, suggesting that alternate pathways exist for leaf patterning. Here, we describe three genes, PIGGYBACK1 (PGY1), PGY2 and PGY3, which alter leaf patterning in the absence of AS1. All three pgy mutants develop dramatic ectopic lamina outgrowths on the adaxial side of the leaf in an as1 mutant background. This leaf-patterning defect is enhanced by mutations in the adaxial HD-ZIPIII gene REVOLUTA (REV), and is suppressed by mutations in abaxial KANADI genes. Thus, PGY genes influence leaf development via genetic interactions with the HD-ZIPIII-KANADI pathway. PGY1, PGY2 and PGY3 encode cytoplasmic large subunit ribosomal proteins, L10a, L9 and L5, respectively. Our results suggest a role for translation in leaf dorsoventral patterning and indicate that ribosomes are regulators of key patterning events in plant development.


Subject(s)
Arabidopsis/genetics , Genes, Plant , Plant Leaves/growth & development , Ribosomal Proteins/physiology , Alleles , Arabidopsis/growth & development , Arabidopsis/physiology , Arabidopsis Proteins/genetics , Arabidopsis Proteins/physiology , Body Patterning , Gene Expression Regulation, Plant , Homeodomain Proteins/genetics , Homeodomain Proteins/physiology , In Situ Hybridization , Plant Leaves/ultrastructure , Point Mutation , Transcription Factors/genetics , Transcription Factors/physiology
20.
PLoS Genet ; 2(6): e89, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16846251

ABSTRACT

The shoot apical meristem comprises an organized cluster of cells with a central region population of self-maintaining stem cells providing peripheral region cells that are recruited to form differentiated lateral organs. Leaves, the principal lateral organ of the shoot, develop as polar structures typically with distinct dorsoventrality. Interdependent interactions between the meristem and developing leaf provide essential cues that serve both to maintain the meristem and to pattern dorsoventrality in the initiating leaf. A key component of both processes are the class III HD-ZIP genes. Current findings are defining the developmental role of members of this family and are identifying multiple mechanisms controlling expression of these genes.


Subject(s)
Arabidopsis Proteins/genetics , Homeodomain Proteins/genetics , Meristem/growth & development , Plant Shoots/cytology , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Morphogenesis , Plant Leaves/cytology , Plant Leaves/growth & development , Plant Shoots/growth & development , Transcription Factors/genetics
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