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Sequential screens are designed based on proteomics and the yeast two-hybrid (Y2H) assay to search for the proteins that directly interact with HXK1 (Arabidopsis hexokinase 1) in the nucleus. Genetic, transgenic, biochemical and molecular evidence have supported an essential role of the novel HXK1 nuclear complex in controlling diverse glucose responses in whole plants.

A high-throughput DNA sequencing is adapted to the discovery of endogenous small RNAs from the moss Physcomitrella patens and Arabidopsis. The results have indicated that dual miRNA complementary sites are a trigger for siRNA biogenesis that is conserved for the past 400 million years and have provided insights into the recognition and silencing of aberrant RNAs.

A cell-based genetic screen of virulence factors helped to identify AvrPto and AvrPtoB as potent and unique suppressors of early defense screen gene transcription and MAP kinase signaling. The studies revealed a fundamental role of microbe-associated molecular pattern (MAMP) signaling in nonhost immunity, and a novel action of type III effectors from pathogenic bacteria.

The local reduction of expression of the RETINOBLASTOMA-RELATED (RBR) gene in Arabidopsis roots increases the amount of stem cells without affecting cell cycle duration in mitotically active cells. Expression analysis and genetic interactions position RBR-mediated regulation of the stem cell state downstream of the patterning gene SCARECROW.

CLAVATA1 (CLV1) regulates stem cell accumulation at Arabidopsis shoot and flower meristems. CLV1 encodes a receptor-like kinase, but very little is known about downstream signaling components of receptor-kinase signaling in plants, poltergeist (pol) mutants suppress the accumulation of stem cells that occur in clv mutants, and POL has been hypothesized to modulate CLV1 signaling. The POL gene, which encodes a functional protein phosphatase type 2C, is a member of a six-gene family in Arabidopsis. We have isolated loss-of-function alleles for each of the five POL-like genes (PLL1-PLL5). All gene family members, with the exception of PLL3, are expressed broadly within the plant, albeit at differing levels. We show that PLL1 regulates meristem development in parallel with POL. We observe a strong dosage sensitivity at the meristem for POL and PLL1 function in both loss- and gain-of-function analyses, suggesting that these proteins are rate-limiting modulators of stem cell specification. PLL genes also function outside of the meristem: POL and PLL1 regulate pedicel length in interaction with ERECTA, while PLL4 and PLL5 regulate leaf development. We observed no developmental role for either PLL2 or PLL3 based on single and double mutant analysis. Keywords: Stem cell; Organogenesis; Leaf morphogenesis; Receptor

Initiation of transcription mediated by RNA polymerase II requires a number of transcription factors among which TFIID is the major core promoter recognition factor. TFIID is composed of highly conserved factors which include the TATA-binding protein (TBP) and about 14 TBP-associated factors (TAFs). Recently, the complete Arabidopsis TAF family has been identified. To obtain functional information about Arabidopsis TAFs, we analyzed a T-DNA insertion mutant for AtTAF6. Segregation analysis showed that plants homozygous for the mutant allele were never found, indicating that inhibition of the AtTAF6 function is lethal. Genetic experiments also revealed that the male gametophyte was affected by the attaf6 mutation since significant reduced transmission of the mutant allele through the male gametophyte was observed. Detailed histological and morphological analysis showed that the T-DNA insertion in AtTAF6 specifically affects pollen tube growth, indicating that the transcriptional regulation of only a specific subset of genes is controlled by this basal transcription factor. Keywords: TAF6; TFIID; Arabidopsis; Pollen tube; Gametophyte; Transcription

The development of trichomes and root hairs in Arabidopsis provide useful models for the study of cell fate determination in plants. A common network of putative transcriptional regulators, including the small MYB proteins TRIPTYCHON (TRY) and CAPRICE (CPC), is known to influence the patterning of both cell types. Here, we used an activation tagging strategy to identify a new regulator, ENHANCER OF TRY AND CPC 1 (ETC1). The ETC1 sequence is similar to TRY and CPC, and ETC1 overexpression causes a reduction in trichome formation and excessive root hair production. The etc1 single mutant has no significant phenotype, but it enhances the effect of cpc and try on trichome and root hair development, which shows that ETC1 function is partially redundant with TRY and CPC. In addition, the etc1 try cpc triple mutant has novel phenotypes, revealing previously unrecognized roles for these regulators in epidermis development. An ETC1 promoter reporter gene fusion is expressed in the developing trichome and non-hair cells, similar to the expression of TRY and CPC. These results suggest that ETC1, TRY, and CPC act in concert to repress the trichome cell fate in the shoot epidermis and the non-hair cell fate in the root epidermis. Keywords: Epidermis; Pattern formation; Trichomes; Root hairs; Cell differentiation; Embryogenesis; Arabidopsis thaliana

This report describes the characterisation of ATHB16, a novel Arabidopsis thaliana homeobox gene, which encodes a homeodomainleucine zipper class I (HDZip I) protein. We demonstrate that ATHB 16 functions as a growth regulator, potentially as a component in the light-sensing mechanism of the plant. Endogenous ATHB16 mRNA was detected in all organs of Arabidopsis, at highest abundance in rosette leaves. Reduced levels of ATHB16 expression in transgenic Arabidopsis plants caused an increase in leaf cell expansion and consequently an increased size of the leaves, whereas leaf shape was unaffected. Transgenic plants with increased ATHB16 mRNA levels developed leaves that were smaller than wild-type leaves. Therefore, we suggest ATHB16 to act as a negative regulator of leaf cell expansion. Furthermore, the flowering time response to photoperiod was increased in plants with reduced ATHB16 levels but reduced in plants with elevated ATHB16 levels, indicating that ATHB16 has an additional role as a suppressor of the flowering time sensitivity to photoperiod in wild-type Arabidopsis. As deduced from the response of transgenic plants with altered levels of ATHB16 expression in hypocotyl elongation assays, the gene may act to regulate plant development as a mediator of a blue light response. Keywords: Light response; Flowering time; Transcription factor; HDZip; Leucine zipper; Transgenic plants

Research has been conducted on the cyclic electron flow around photosystem I. The hypothesis that the defect in this cyclic electron flow should lead to insufficient (Delta)pH generation has been tested and the results are included.

Research has been conducted on the Arabidopsis mutations. The isolation of these mutations has been carried out in investigating embryo and endosperm development control by the female gametophyte and the details are reported.

Research has been conducted on RPM1 protein resistance in Arabidopsis against Pseudomonas syringae. The results indicate that RPM1-interacting protein is a negative regulator of plant defence which facilitates pathogen growth.

Research has been conducted on the putative auxin efflux carriers Arabidopsis PIN4. Results indicate that AtPIN4 generates a sink for auxin the quiescent center of the root meristem essential for auxin distribution and patterning.

Most signal transduction pathways central to development are not shared by plants and animals. Such is the case of the Wingless/Wnt signaling pathway, whose components play key roles in metazoan pattern formation and tumorigenesis, but are absent in plants, with the exception of SHAGGY/GSK3, a cytoplasmic protein kinase represented in the genome of Arabidopsis thaliana by a family of 10 AtSK genes for which mutational evidence is scarce. Here, we describe the characterization of mutant alleles of the Arabidopsis ULTRACURVATA1 (UCU1) gene, the two strongest of which dramatically reduce cell expansion along the proximodistal axis, dwarfing the mutant plants, whose cells expand properly across but not along most organs. Proximodistal expansion of adaxial (dorsal) and abaxial (ventral) leaf cells exhibits a differential dependence on UCU1 function, as suggested by the leaves of ucu1 mutants, which are rolled spirally downward in a circinate manner. We have positionally cloned the UCU1 gene, which encodes an AtSK protein involved in the cross-talk between auxin and brassinosteroid signaling pathways, as indicated by the responses of ucu1 mutants to plant hormones and the phenotypes of double mutants involving ucu1 alleles. Key Words: Arabidopsis; plant leaf development; ultracurvata mutants; brassinosteroid signaling; SHAGGY/GSK3-like kinases.

Cell lineage has been used to explain the stomatal distribution in several plant species. We have used transgenic plants carrying a 35SGUS::Ac construct that produces clonal sectors to analyze the possible role of cell lineage during the establishment of stomatal patterning in Arabidopsis leaves. The analysis of sectors ranging from two to eighteen cells supports the conclusion that most stomatal complexes derive from a single and immediate precursor cell through a stereotyped pattern of three unequal cell divisions followed by a final equal one. In addition, it shows that the successive cell divisions take place at a constant angle (approximately 60 [degrees]) with respect to the previous one. Interestingly, this angular dimension shifts from 60 [degrees] to 0 [degrees] in the last cell division that gives rise to the stoma. These sectors also reveal the development of both clockwise and counterclockwise patterns of cell divisions during stomatal development in approximately equal numbers. Our clonal analysis indicates that cell divisions involved in the development of stomatal complexes are probably the last ones contributing to epidermal growth and development. Finally, the stereotyped pattern of cell divisions that culminates in the formation of stomatal complexes indicates that cell lineage plays a very important role during stomatal pattern establishment. Key Words: Activator element; anisocytic stomatal complex; Arabidopsis; clockwise; clonal analysis; counterclockwise; epidermis; monoclonal; polyclonal; stomatal pattern.

Research has been conducted on the flowering acceleration caused by a long period of low temperature, vernalization. The study of the VERNALIZATION 2 gene which mediates vernalization and encodes a nuclear-localized zinc finger protein has been carried out and the results are discussed.

Research has been conducted on the homologous self-maintaining systems, floral meristems and shoot apical meristems. The regulatory mechanisms of these systems have been investigated via the interactions between WUSCHEL which specifies the identity of the stem cell and AGAMOUS required for the floral determinacy and the results are reported.

Research has been conducted on the homeogenic gene important for the organ fate specification and stem cell proliferation limitation in Arabidopsis flowers. Results indicate that the floral protein expressed throughout the flower cooperates with the homeodomain protein and activates the homeogenic gene in the center of the flower.

Research shows that FASCIATA1 and FASCIATA2 genes maintain cellular and functional organization of the shoot and root apical meristems in Arabidopsis. Data indicate that the FASCIATA gene products are analogous to chromatin assembly factor-1, which helps maintain stability of gene expression status during the apical meristems postembryonic development.

Research reveals that plant disease resistance is mediated by MAP kinase 4 (MPK4) activity and its inactivation by transposons result in the development of systemic acquired resistance, elevated salicylic acid levels, and resistance to virulent pathogens.

A clock-controlled gene, FKF1, has been found to regulate the transition to flowering in Arabidopsis. A late-flowering mutant of the plant was isolated. IKt is rescued by vernalization of gibberellin treatment. FDF1 was positionally coned. It encodes a novel protein with a PAS domain like that of the flavin-binding region of certain photoreceptors, six kelch repeats predicted to fold into a beta propeller and an F box characteristic of proteins that direct ubiquitin-mediated degradation.

Regulation in plants of auxin response by the protein kinase PINOID is discussed. Arabidopsis plants with PINOID (PID) gene mutations have a pleiotropic shoot phenotype mimicking that of plants grown on auxin transport inhibitor or plants mutated for the auxin efflux carrier PINFORMED (PIN) with various defects. PID was cloned and found to be transiently expressed in the embryo and in starting floral anlagen. That shows a specific role for PID in promoting primordium development.

A novel gene, WEREWOLF (WER), a MYB-related protein in Arabidopsis, is discussed. It is a position-dependent regulator of epidermal cell patterning. Study results suggest a simple model which would explain specification of the two root epidermal cell types and give insight into molecular mechanisms that control cell patterning.

Cell cycling plays an important role in plant development, including: (1) organ morphogenesis, (2) cell proliferation within tissues, and (3) cell differentiation. In this study we use a cyclin::(beta)-glucuronidase reporter construct to characterize spatial and temporal patterns of cell cycling at each of these levels during wild-type development in the model genetic organism Arabidopsis thaliana (Columbia). We show that a key morphogenetic event in leaf development, blade formation, is highly correlated with localized cell cycling at the primordium margin. However, tissue layers are established by a more diffuse distribution of cycling cells that does not directly involve the marginal zone. During leaf expansion, tissue proliferation shows a strong longitudinal gradient, with basiplastic polarity. Tissue layers differ in pattern of proliferative cell divisions: cell cycling of palisade mesophyll precursors is prolonged in comparison to that of pavement cells of the adjacent epidermal layers, and cells exit the cycle at different characteristic sizes. Cell divisions directly related to formation of stomates and of vascular tissue from their respective precursors occur throughout the period of leaf extension, so that differing tissue patterns reflect superposition of cycling related to cell differentiation on more general tissue proliferation. Our results indicate that cell cycling related to leaf morphogenesis, tissue-specific patterns of cell proliferation, and cell differentiation occurs concurrently during leaf development and suggest that unique regulatory pathways may operate at each level. Key Words: Arabidopsis; cell cycling; cell enlargement; cyclin; leaf development.

Polarity establishment in carpels of Arabidopsis are discussed. They are promoted by distinct mechanisms. Genetic enhancers of the crc mutant phenotype were isolated to shed light on the role of CRABS CLAW (CRC) in carpel development. Mutations representing genes that act redundantly with CRC in control of abaxial-adaxial polarity in the carpel were found.

The female gametophyte (embryo sac or megagametophyte) plays a critical role in sexual reproduction of angiosperms. It is the structure that produces the egg cell and central cell which, following fertilization, give rise to the seed's embryo and endosperm, respectively. In addition, the female gametophyte mediates a host of reproductive processes including pollen tube guidance, fertilization, and the induction of seed development. Several major events occur during megagametogenesis, including syncitial nuclear divisions, cellularization, nuclear migration and fusion, and cell death. While these events have been described morphologically, the molecules regulating them in the female gametophyte are largely unknown. We discuss a genetic screen based on reduced seed set and segregation distortion to identify mutations affecting megagametogenesis and female gametophyte function. We report on the isolation of four mutants (fem1, fem2, fem3, and fem4) and show that the four mutations map to different locations within the genome. Additionally, we show that the fem1 and fem2 mutations affect only the female gametophyte, while the fem3 and fem4 mutations affect both the female and male gametophyte. We analyzed female gametophyte development in these four mutants as well as in the gfa2, gfa3, gfa4, gfa5, and gfa7 mutants. We found that the fem2, fem3, gfa4, and gfa5 mutants abort development at the one-nucleate stage, while the fem1, fem4, gfa2, gfa3, and gfa7 mutants are affected in processes later in development such as polar nuclei fusion and cellularization. The establishment of a genetic screen to identify mutants and the development of a rapid procedure for analyzing mutant phenotypes represent a first step in the isolation of molecules that regulate female gametophyte development and function. Key Words: female gametophyte development; Arabidopsis; nuclear fusion; cellularization; plant reproduction; embryo sac.

The late elongated hypocotyl (lhy) mutation in the Arabidopsis produces day length-insensitive late-flowering plants. Aside from affecting flowering time, this dominant mutation also causes hypocotyl elongation and reduction in chlorophyll content. To further elucidate the phenotypic characters associated with this mutation, genetic studies of the Arabidopsos lhy were conducted. Results revealed that lhy mutation also cause arrhythmia for leaf movements as well as for three clock-regulated genes. It was also found to encode for a transcription factor with features of plant circadian clocks.

Research was conducted to determine homeotic protein heterodimer APETALA3/PISTILLATA (AP3/PI) target genes by examining mRNAs whose levels were affected by post-translational activation of AP3/PI function in floral organs. Flowers were pooled for each sample while the N-terminal gene coding sequence was cloned from a floral cDNA library in lambda ZAPII. Results showed that the expression pattern of the gene identified by differential display was consistent with AP3/PI.

Although the plant epidermis serves primarily a protective role, during plant development some epidermal cells specialize, becoming competent to interact not only with pollen but also with other epidermal cells. In the former case, these interactions mediate recognition, germination, and pollen growth responses and, in the latter case, result in interorgan fusions which, most commonly, alter floral architecture in ways that are thought to promote reproductive success. In either case, all of the initial signaling events must take place across the cell wall and cuticle. In Arabidopsis, mutation of the FIDDLEHEAD gene alters the shoot epidermis such that all epidermal cells become competent to participate in both types of interactions. In fdh-1 mutants, epidermal cells manifest not only a contact-mediated fusion response but also interact with pollen. Since carpel epidermal derivatives manifest both of these properties, we postulated that fdh-1 epidermal cells were ectopically expressing a carpel-like program. In this report we demonstrate that manifestation of the fdh-1 phenotype does not require the product of the AGAMOUS gene, indicating that the phenotype is either independent of the carpel development program or that fdh-1 mutations activate a carpel-specific developmental program downstream of the AG gene. Furthermore, we demonstrate that plants bearing mutations in the fdh-1 gene show significant changes in cell wall and cuticular permeability. Biochemical analyses of the lipid composition of the crude cell wall fraction reveal that fdh-1 cell walls differ from wild-type and manifest significant changes in high-molecular-weight lipid peaks. These results suggest that cell wall and cuticular permeability may be important determinants in developmental signaling between interacting cells and implicate lipids as important factors in modulating the selectivity of the permeability barrier presented by the epidermal cell wall and cuticle.

Nuclear protein ETHYLENE-INSENSITIVE3 (EIN3) and related proteins were analyzed to determine their role in the activation of the ethylene gas response pathway in Arabidopsis. The study utilized various strains, growth conditions and genetic analysis to identify and describe the EIN3-like genes whose predicted translation products have characteristics found in regulatory proteins. Results reveal that mutations in the EIN3 gene in Arabidopsis deter a plant's response to ethylene and that loss of ethylene-mediated effects could lead to an enhanced senescence.

The role of the FCA promoter in the regulation of flowering time in arabidopsis plants was analyzed via X-ray mutagenesis. The arabidopsis fca-mutants exhibited impaired plant development during the vegetative and reproductive stages. The transcript gamma was also characterized as the genetic factor that encodes the FCA protein which promoted the posttranscriptional cascade that regulated flowering time in arabidopsis.

The role of the LSD1 gene in plant cell apoptosis was analyzed in isolated Arabidopsis lsd1 mutants that exhibit constitutive initiation of hyperresponsive response (HR)-like cell death in the absence of pathogen. The Arabidopsis lsd1 mutants did not exhibit spontaneous apoptotic lesions after the initiation of cell death. Superoxide synthesis preceded the onset of cell death in the mutants indicating the role of superoxide in mediating LSD1-induced downregulation of cell death response.

The Arabidopsis NPR1 gene was cloned using a map-based method and was observed to encode a unique protein containing ankyrin repeats. The gene was found to control the onset of systemic resistance and affect local acquired resistance, the ability of plants to inhibit the spread of virulent pathogen infections. Mutations that were observed to terminate NPR1 function included conversion of a cysteine to a tyrosine, disruption of the ankyrin repeat consensus sequence and truncations of the protein.

The cell lineages of the Arabidopsis root meristem are generated when the initial cells undergo asymmetric division. However, mutations such as the scarecrow (SCR) could disrupt the asymmetric division that generates the cortex and endodermis, resulting in roots that are missing one cell layer. A study shows that SCR plays a major role in regulating the root's radial organization.

Arabidopsis COP9 is a component of a large acidic protein complex that is necessary for the light control of a developmental switch. Light modulates the conformation or size of arabidopsis COP9. The complex, which binds heparin, is localized within the nucleus. It was found to contain 12 distinct subunits when biochemically purified to near homogeneity. The COP9 complex could represent a conserved developmental regulator in higher eukaryotes because both COP9 and COP11 have closely related human counterparts.

Flowers develop from the coordinated division and differentiation of cells derived from the shoot apical meristem. By inducing chromosomal deletions in individual shoot apical meristem cells, we have generated Arabidopsis plants that are genetically mosaic for the homeotic PISTILLATA gene. Flowers bearing wild-type PISTILLATA epidermal tissue and mutant pistillata internal tissues are phenotypically normal. Based on this non-cell-autonomy, we suggest that PISTILLATA controls the production of a substance involved in cell-cell communication between the outer and inner tissue layers of the flower. These mosaic flowers were also used to assess the relative contributions of meristematic cells to the developing floral organs. These observations indicate that meristematic cells have discrete but somewhat variable contributions to the Arabidopsis flower. We have used these results to construct a fate map of the Arabidopsis floral primordium.

The Arabidopsis plant exhibits an abnormal organization of cells at its embryonic phase that may be due to mutations in the Knolle gene. The normal embryo forms radial patterns of cells that begin to differentiate into functional types according to this pattern. However, mutations in the Knolle gene lead to the formation of cells with multiple nuclei or incomplete cell walls. The protein produced by the gene was found to have a structure similar to syntaxins and to regulate vesicular trafficking.

Primary meristems of the shoot and the root play key roles in the development of adult plants. Unlike pattern formation in animals, plant development passes through various embryonic stages before the adult form is reached. The central and peripheral zones in the meristems add new structures to produce secondary roots and leaves. Continuous expression of genes establishes the primary meristems of the shoot and root in the embryo, which eventually leads to body organization of the seedling.

The constans (CO) gene of Arabidopsis appears to be a transcriptional activator required to promote flowering. Analysis of isolated CO revealed two zinc fingers in the amino acid sequence. This could indicate a DNA binding function, suggesting a transcription factor function.

Genetic analysis of an embryo-defective Arabidopsis mutant, twin, to understand the process of twin or triplet seedling formation reveals that embryogenic transformation in the cell due to degradation of a single genetic locus suspensor enables the twin to display polyembryony. The mutants also display several developmental abnormalities such as random cell division patterns and morphological features. Viability of the twin seedlings reveals that the suspensor determines the embryonic polarity and helps terminate the developmental processes that are seen only in normal embryos.

DET1 is a nuclear localized protein that negatively regulates steady state levels of mRNAs that do not vary between light and dark-grown wild-type plants and influences morphogenesis and gene expression following post-transcriptional modification. DET1 facilitates the DNA binding activity called CA-1 with its cis-acting site forming transient part of CA-1 complex. Spatial and temporal development signals are coordinated with light signals through modification of DET1 activity.

Gene COP9 is a component of novel light signaling complex which is stabilized by the activation of COP8 and COP11 genes. The COP9 complex in dark grown seedlings transforms to more stable light complex upon exposure to light which modulates COP9 complex activity post translationally. Light signals received by phytochromes and a blue light receptor are converged and transduced through a regulatory cascade characterized by COP, COP8, COP11 and others that controls seedling development.

Six Arabidopsis mutants that constitute the necrotic lesion on leaves define four different loci. The definition indicates that the lesions are similar to the lesions from disease and occur only when the pathogens are absent. Histochemical and molecular markers of plant disease resistance response are associated with lesion formation in five mutants.

Co-ordinate nuclear and chloroplast gene expressions are required for chloroplast development. The transcription of some nuclear genes, which encode the proteins which are related to photosynthesis with the chloroplast function, is coupled with a putative signal from the chloroplast. The three Arabidopsis nuclear genes, which are essential for coupling the expression of certain nuclear genes with the functional state of the chloroplast, are also identified. Nuclear gene expression is allowed by the homozygous recessive GUN mutations when the chloroplast development is absent. The homozygous recessive GUN mutation also interferes with the switch from dark-grown to light-grown development.

A new Arabidopsis gene was identified using the triple response of dark grown seedlings to isolate constitutive triple response (ctr) mutants. The gene, designated CTR1, acts downstream of EIN1 but upstream of the EIN3 gene product. Sequence analysis showed that the protein encoded by CTR1 is highly similar to the serine/threonine protein kinases. It is proposed that CTR1 acts as a negative regulator of a multistep signal transduction pathway via phosphorylation of protein(s) in a cascade.

The first comprehensive DNA methylation map of an entire genome, at 35 base pair resolution, using the flowering plant Arabidopsis thaliana as a model is reported. Whole-genome tiling-array transcriptional profiling of DNA methyltransferase null mutants identified hundreds of genes and intergenic noncoding RNAs with altered expression levels, many of which might be epigenetically controlled by DNA methylation.

A study tests the proposal that a common set of signaling components might integrate inputs from multiple hormones to regulate growth, by asking whether different hormones converge on a common set of transcriptional targets in Arabidopsis seedlings. Results show that different hormones appear to regulate distinct members of protein families, leading to the conclusion that there is no core transcriptional growth-regulatory module in young Arabidopsis seedlings.

DNA glycosylase DEMETER (DME) establishes endosperm maternal-allele-specific hypomethylation at the MEDEA (MEA) gene. DME removes 5-methylcytosine for activating the maternal allele and thus establishes MEA imprinting.

The activation of the maternal copy of the imprinted MEDEA Polycomb gene by DEMETER is discussed. It is demonstrated that this activation involves DNA demethylation of MEDEA by DMETER, which shows that silencing of the paternal MEDEA allele is independent of DNA methylation, and is controlled by maternal expression of MEDEA itself.

The PLETHORA1 (PLT1) AND PLT genes encoding AP2 class putative transcription factors that are essential for QC specification and stem cell activity are presented. The PLT genes are transcribed in response to auxin accumulation and are dependent on auxin response transcription factors.

The seedpod, Arabidopsis opens through a spring loaded mechanism known as pod shatter, which is necessary for dispersal of seeds and INDEHISCENT, an atypical bHLH protein is identified for fruit opening. It was found that FRUITFULL, which is a member of the MADS-domain transcription factor family, is needed for fruit growth.