In Arabidopsis several mutations that decrease cell proliferation activity often trigger excessive cell enlargement, a phenomenon that we named as compensation. However, the nature of such organ-wide coordination between cell proliferation and expansion is still obscure. We isolated and characterized six mutants fugu1- fugu5 and erecta, together with an3 and KRP2 overexpressor, all of which exhibit compensation. Time course analysis of leaf development revealed postmitotic cell enlargement is mediated by either an increase in the rate or duration of cell expansion in fugu2 and fugu5, respectively. Thus, we chosed these two mutants for further analyses. As the first step of such studies, DNA microarray analysis where fugu2 and fugu5 were used as representatives revealed that substantially different sets of genes were affected between fugu2 and fugu5. Map-based cloning of FUGU2 gene revealed that it is the FASCIATA1 gene. We will discuss possible mechanisms of compensation based on our recent findings.

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The analysis of cell specificity of gene expression is important to understand the state of differentiation for (particular) vascular cells. We selectively killed developing tracheary element (TE) cells in Zinnia TE-inductive suspension culture to obtain mRNA samples from live TE-free cell population. A comprehensive gene expression analysis on such mRNA samples by DNA microarray revealed that there are significant differences in TE specificity among expression patterns of previously annotated "TE-associated" or "TE-specific" genes.
We identified putative Arabidopsis homologs of some of these Zinnia genes to examine their promoter activities in situ. Arabidopsis transformants containing reporter genes fused with promoter regions of these homolog genes showed signal patterns that are compatible with above microarray data. These findings provide important insights into mechanisms of vascular cell differentiation and TE programmed cell death/autolysis.

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Myrosin cells in Capparales plants are idioblasts that accumulate myrosinase, which hydrolyzes glucosinolates to produce toxic compounds for repelling pests. We previously showed that Arabidopsis atvam3 mutants have abnormally larger number of myrosin cells. Myrosin cells are scattered along leaf veins in wild-type leaves, whereas they develop a network throughout the leaves in the mutants (1). To elucidate how myrosin cells differentiate, we analyzed atvam3 mutants. We found that atvam3 leaves have the distinguishably immature higher-order veins and abnormally discontinuous second-order veins. DNA microarray analysis revealed that young atvam3 leaves down-regulated a significant number of genes that include the genes related to biosynthesis and transport of phytohormones and the genes response to phytohormones. We discuss about the involvement of phytohormones in the differentiation of myrosin cells of the leaves.
(1)Ueda et al. (2006) Plant Cell Physiol., 47,164-175

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Leguminous plants have a systemic negative feedback regulatory mechanism called 'autoregulation' of nodulation. The gene involving in autoregulation of nodulation: HAR1 encodes receptor-like kinase (RLK) and in a comparison of Arabidopsis RLKs, HAR1 showed the highest similarity with CLAVATA1 (CLV1). CLV1 forms a receptor complex with receptor like protein; CLV2, and negatively regulates the formation of the shoot and floral meristem via a cell-cell communication involving CLAVATA3 (CLV3) peptide. Based on CLAVATA model, there is a possibility that HAR1 forms the receptor complex with LjCLV2 and recognize LjCLV3 as its ligand in Lotus japonicus. We found CLV2-like sequence (LjCLV2) and CLV3-like sequence (LjCLV3) from the genome of Lotus japonicus, so we generated LjCLV2- and LjCLV3-RNAi lines. LjCLV2-RNAi lines showed the increase in the number of nodule, whereas LjCLV3-RNAi lines showed fasciated shoots. These results indicate LjCLV2 involves in autoregulation, and LjCLV3 involves in maintenance of shoot apical meristem.

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BOP1 and BOP2 genes (BOP genes) are thought to regulate determinacy of leaf development in Arabidopsis thaliana, since recessive bop1/bop2 double mutant exhibits indeterminate growth of leaf blade. Interestingly, some wild plants exhibit indeterminate leaf morphogenesis like the bop1/bop2 double mutant. For example, in so-called one-leaf plants, belonging to the family Gesneriaceae, one of the two cotyledons grows indeterminately.
We isolated BOP homologs from a one-leaf plant (Monophyllaea glabra) and a taxonomically closely related plant Saintpaulia ionantha that develops determinate leave. To know whether those BOP homologs are functionally conserved in Monophyllaea and Saintpaulia, we determined expression pattern of those homologs, and introduced those homologs under control of the 35S promoter into the bop1/bop2 double mutant of Arabidopsis thaliana. Based on those results, we will also discuss if the indeterminate nature of leaf in the one-leaf plants is attributable to loss (or change) of function of the BOP genes.

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ASYMMETRIC LEAVES2 (AS2) gene encodes a plant specific protein that has cysteine repeats, conserved glycine and leucine-zipper-like sequence in the N-terminal half. Leaves of loss-of-function of AS2 mutants have the asymmetric shape of the lamina and a malformed vein system. AS2 is involved in development of a symmetric leaf lamina and the establishment of the leaf venation system. Although the AS2 transcripts were detected in the root by Northern blot analysis, roots of as2 mutants did not exhibit visible phenotypic change. To study the function of AS2 in the root, we examined GUS activity in transgenic plants that had been transformed with a GUS gene controlled by the AS2 promoter. GUS expression was observed not only in the shoot apical meristem and the developing leaves but also in the root caps. We investigate the effects of mutation in AS2 or over-expression of AS2 on the structures of the root tips.

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For better understanding of position-dependent growth process, novel Arabidopsis ibo mutants exhibiting ectopic tip growth in hypocotyl epidermal cells were isolated. Hypocotyl epidermal cells in ibo1 underwent ectopic tip growth at the center of the cell to form a protrusion reminiscent of root hair. Similar ectopic protrusions were observed in epidermal cells in petioles and midribs of ibo1. ibo1 mutations had no adverse effects on differentiation patterns of root hairs, stomata, and trichomes. ibo1 exhibited normal expression pattern of GL2, CPC, and SHV3 family. Ectopic tip growth in ibo1 was preferentially induced in non-stomatal cell files expressing GL2 and CPC. Ectopic tip growth in ibo1 was reduced by the application of ethylene-biosynthesis inhibitor, and restored by the ethylene precursor. cpc-1 ibo1 double mutants exhibited additive phenotypes; ectopic protrusions in hypocotyls and reduced root hair formation. Possible function of IBO1 in the suppression of ectopic tip growth will be discussed.

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Plant leaves are flat and symmetric organs and develop from a shoot apical meristem along three axes, proximal-distal, adaxial-abaxial and medial-lateral axes. The asymmetric leaves2 (as2) and as1 mutants of Arabidopsis thaliana show similar phenotypes with asymmetrical lobes along the leaf margin and with asymmetrically and downwardly curled leaves. Previously, we and other groups showed that both of AS2 and AS1 repress the class 1 KNOX genes, BP, KNAT2 and KNAT6. To know the genes regulated by AS2 and AS1, microarray analysis was done. On the basis of expression profiles of wild-type, as2-1, as1-1, as2-1/pAS1::AS2, which overexpresses AS2, and 35S::AS1, 22,746 genes were classified. The levels of BP and the genes in the same class as BP were decreased in the as2-1 and as1-1 mutants and were increased in the as2-1/pAS1::AS2 and 35S::AS1 plants. The expression of these genes may be regulated by both of AS2 and AS1.

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Cryptomeria japonica is one of the most important Japanese conifer species. We consider genetic modification (GM) is a powerful tool for breeding. But the transfer of foreign genes from GM plants to related plant species by pollen has been cited as an environmental concern. For the purpose of creating male sterile GM Cryptomeria japonica, we are trying to identify genes related to male flower formation.
To identify genes preferentially expressed during male strobilus development, we constructed 4 male strobili subtracted libraries on the basis of PCR-selected subtraction using a pool of shoot tissues as the driver and male strobili as tester. We isolated some clones from 25th November male strobili subtracted library. Sequence analysis showed that one of the clones we isolated was similar to the sunflower anther specific cell wall protein, SF18. Now we are trying to isolate male strobilus specific genes from other developmental stages.

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We isolated a recessive mutant defective in root hair elongation from RIKEN Arabidopsis Ds transposon insertion lines. In the mutant, 15-1096-1, the tip growths of almost all root hairs are stopped and their tips are ruptured. The transposon is inserted into a gene encoding a glycosylphosphatidylinositol (GPI) -anchored protein, indicating that 15-1096-1 is allelic to the shv3 (Parker et al., 2000; Jones, et al., 2006). Arabidopsis has five proteins with the same domain structure as SHV3 that seems unique to plants. Expression analysis of the corresponding genes showed their distinct and overlapping tissue distributions. The double mutant between shv3 and disruption of the family member showed some additional phenotypes related to cell expansion and had aberrant cell wall, suggesting that SHV3 and the family members are novel players involved in cell wall organization required for the regulation of cell expansion.

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In the root meristem (RM), stem cells surround niche cells, the quiescent center. Stem cells maintain their stemness within their niche and commence stereotyped cell division sequences. Until recently, little is known about the molecular mechanisms underlying the stem cell maintenance in RM. Previous experiments have shown that laser-ablated stem cells could be compensated for by adjacent cells. This cell invasion process often results in abnormal root cell patterns. These observations suggest that mutants defective in the root stem cell maintenance likely exhibit abnormal root cell patterning rather than retardation of root growth.
Based on this working hypothesis, we isolated several Arabidopsis mutants defective in root cell patterns. One of the mutant contained reduced number of cells in the root vascular tissue, and its causal gene was found to encode a novel protein containing WD40-motifs. We will report detailed characterization of the mutants and discuss functions of their causal genes.

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We have isolated eight dominant mutants with abnormal root cell patterns using the GAL4/UAS activation tagging system. These mutants were collectively named UAS-tagged root patterning (urp). Two of them, urp4-1D and urp5-1D, showed enhanced cell division in lateral root cap and epidermis. Determination of the UAS insertion sites, followed by cosegregation and recapituration analyses, indicated that the mutant phenotype was caused by ectopic expression of homologous genes encoding plant-specific transcription factor-like proteins. The URP4 recapituration lines showed severer phenotype than that of original urp4-1D, giving rise to callus-like morphology. A callus-specific gene was found to be induced in these mutants and the URP4 promoter was active in callus. Furthermore, expressions of other homologous genes were also elevated in the URP4- and URP5-overexpressing plants. These observations suggest that URP4 and URP5 proteins function either in enhancing cell proliferation or in repressing cell differentiation.

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Phytohormone auxin is involved in various growth responses including axis formation during embryogenesis, organogenesis, vascular patterning, and tropism. Although auxin was the phytohormone discovered over 100 years ago, no molecular mechanisms of its biosynthesis, an essential aspect of auxin homeostasis, have been fully elucidated. To reveal the action of auxin during embryogenesis, we tried to identify the site and function of auxin biosynthesis. We analyzed expression of genes involved in Tryptophan-dependent IAA biosynthesis pathways, such as CYP79B2, CYP79B3, YUCCA1, 2, 3, 4, NIT1, 2, 3, and AAO1. Expression patterns of these genes were tightly regulated temporally and spatially during embryogenesis. Especially, YUCCA expression domains were identical to predicted sites of auxin biosynthesis. To elucidate the function of YUCCA genes, we performed the phenotype analysis of yucca mutants. yucca mutants exhibited the defects of organ development. These results suggest that YUCCA genes function as the origin of polar auxin transport.

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CRES-T is a dominant and efficient gene silencing system which represses the expression of target gene and is consequently effective even in the presence of functionally-redundant transcription factors. We evaluate CRES-T as a tool for the modification of phenotypes through the production of transgenic Pharbitis nil. In AP3SRDX flowers, changes in phenotype was not observed. In AGSRDX flowers, development of sepals, petals and stamens were suppressed and pistil protruded from sepals in early stage, showing not loss-of-C-class function phenotypes but loss-of-B-class function. Results of RT-PCR analysis showed that changes in expression patterns of endogenous B function genes, namely PnAP3 and PnPI. These results suggest that CRES-T system functions in Pharbitis nil, while there are some variations in function of transcription factors among plant species.
This study is supported by the Research Project for Utilizing Advanced Technologies in Agriculture, Forestry and Fisheries.

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Previously tissue specificity of MSG2/IAA19 gene expression was examined by northern blot hybridization or MSG2 promoter-GUS reporter (Tatematsu et al., 2004). In the present study, firefly luciferase (LUC) was employed for the live tissue imaging of the MSG2 promoter activity as well as the MSG2 protein level. The 3 kb-long MSG2 promoter fusion of LUC gene was stably introduced into Arabidopsis plants. An ultra-sensitive camera system revealed the luciferase images of hypocotyls which were similar to those of promoter-GUS and showed transient auxin induction of the LUC signals. Hypocotyls expressing the MSG2-LUC fusion protein showed much weaker signals than those of the promoter fusion. Signals of the protein fusion with the mutant msg2 protein were stronger than those with the wild-type protein. Auxin treatment transiently increased signals from both of the fusion proteins. We showed, for the first time, spatial and temporal expression of Aux/IAA genes in living plants.

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A previous study demonstrated that two stromal proteins, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and glutamine synthetase, were released from chloroplasts into specific bodies, named Rubisco-containing bodies (RCBs), in wheat leaves. In this study, we visualized RCBs in living cells of transgenic Arabidopsis plants expressing stroma-targeted fluorescent proteins, and examined the involvement of autophagy on the accumulation and degradation of RCBs. In starved leaves treated with concanamycin A, we observed spherical bodies exhibiting GFP or DsRed fluorescence and Brownian movement in the vacuole but no chlorophyll fluorescence. Immuno-EM double-labeled with antibodies against RBCL and GFP confirmed that these fluorescent bodies correspond to RCBs. RCBs were not observed in leaves of atg mutant (Atatg5-1). In addition, stroma-targeted DsRed was co-localized with GFP-ATG8, which can be used as a marker for autophagosome, in spherical bodies found in the vacuole. These results indicate that stromal proteins can be degraded by ATG-dependent autophagic process under starved conditions.

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During leaf senescence, the degradation of chloroplast proteins represents one of the nitrogen translocation mechanisms. Rubisco accounts for 12-35% of total leaf nitrogen and is the main source for nitrogen translocation. In wheat and barley, Rubisco content decreases much faster than the number of chloroplast. Therefore, it is thought that Rubisco is either degraded within chloroplasts, or by autophagy-like transport pathway via RCBs (Rubisco-containing bodies), or both. In this study, we analyzed changes in Rubisco, leaf nitrogen, chlorophyll contents and chloroplasts number during leaf senescence in wild-type Arabidopsis and autophagy defected mutant, Atatg4a4b-1.
The amount of Rubisco, leaf nitrogen and chlorophyll decreased equally in both Atatg4a4b-1 and in the wild-type, until 80% of Rubisco was decreased. Subsequently, Atatg4a4b-1 senesced faster than wild-type. However, the chloroplast number remained stable until the majority of Rubisco was degraded. As the result, Atatg4a4b-1 mutant retained the equivalent potential to degrade chloroplast proteins to wild-type.

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To clarify the processes involved in plant immunity, we have isolated and characterized Arabidopsis mutant, cad1, which shows a phenotype that mimics the lesions seen in the hypersensitive response. Inoculation of cad1 mutant plants with virulence pathogen shows that the cad1 mutation results in the restriction of bacterial growth (Plant Cell Physiol. 2005, 46: 902-912). The mutant enhances gene expression of the plant defensin 1.2 which is related to the plant defense pathway regulated by ethylene and jasmonic acid (JA). The mutant leaded to increase in content of JA, while did not show overproduction of ethylene. All the results suggest that resistance to the pathogen in the mutant is associated to the genes of ERF protein which controls ethylene-responsive genes. Microarray analysis using the cad1 mutant revealed some gene for the ERF genes which are likely involved in plant defense. Characters of the ERF genes will be reported.

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The cell line GTH4 was generated from the F₁ hybrid of Nicotiana gossei x N. tabacum which reveals lethality at seedling stage. The cells proliferated at 37 C but died at 26 C. Inhibitor treatments suggested that cell death depends on expression of genes in the cell at 37 C. The mutant cell line GTH4S does not die, suggesting that GTH4S does not express the genes which are involved in the cell death. Accordingly, it was worth comparing the differences in the genes expressed between GTH4 and GTH4S. To find out the genes involved in the cell death process, 100 x 10³ cDNA clones of GTH4 have been analyzed by differential screening using cDNA probes prepared by RNA of GTH4 or GTH4S. Three clones which were specific to GTH4, NADH dehydrogenase subunit 1 of N.tabacum and two genomic sequences of chloroplast of Solanaceae plants, were found.

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We have been carrying out phenotypic characterization of two T-DNA insertion lines of the IQM1 gene available in the Salk T-DNA library. The IQM1 gene consists of 9 exons, and its product contains an IQ motif to which calmodulin binds in the absence of calcium ion. T-DNA inserted in the first exon and the 6th intron of IQM1 in iqm1-1 and iqm1-2, respectively. RT-PCR analyses showed that the IQM1 mRNA was not transcribed downstream of the insertion site in either mutant. Both mutant seedlings displayed shorter primary roots than wild type. Though auxin response factor (arf) 8-1 (Tian et al., 2004) is normal in root growth, introduction of the arf8-1 mutation into iqm1-2 inhibited root growth further. RT-PCR analyses showed that IQM1 was light-inducible, and that it was also positively regulated by ARF8 in the dark. These results suggest that IQM1 is involved in light, auxin and calmodulin signaling.

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We have developed a new bioassay named Dish Pack Method for analyzing volatile allelochemicals. In this method, leaves of plants were put into one of the holes in a 6-well-multi-dish. Each side of the multi-dish was sealed and put in incubator. The growth of test plants was measured after 4 days. It is possible to analyze the internal volatile gas collected from the hole with gas-tight-syringe through the septum set up on the holes. Volatile compounds from these test plants were analyzed by GC-MS. From Leguminosae and Papaveraceae plants, carbonyl compounds (trans-2-hexenal and cis-3-hexenol) were identified as major compounds. From Compositaea and Labitaea, monoterpenoids (α-Pinene, Limonene, Myrcene et al.) were mainly identified. Spider flower (Cleome spinosa) contained strong volatile allelochemical. Methyl isothiocyanate (MITC) was identified in Spider flower by GC-MS. MITC was released from injured leaves. Volatile allelopathic activity of Cleome cultivars were also evaluated.

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Allelopathic activities of newly introduced plants were evaluated using Sandwich method (for root exudates) and Plant Box method (for leaf leachates).
By Sandwich method, more than 1000 samples ware compiled and the results obtained using 10mg of leaves in 10cm² shows the normal distribution. Sorghum, Oxalis, and Rosaceae family showed strong inhibitory activity.
By Plant Box method, Clarkia unguiculata, Gypsophila paniculata, Oenothera hookeri, Trifolium incarnatum, Ipomopsis rubra, Silene armeria, Avena strigos and, Anisantha madritensis showed strong inhibitory activity. Allelopathic activity of Astragalus sinicus, known as Chinese milk vetch was weak, but we found prominent inhibitory activity in newly introduced Astragalus.

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Members of plant-specific Dof transcription factors have been suggested to play various roles in growth and development and in the responses to phytohormones and environmental signals in various plant species. Arabidopsis has 36 members of Dof transcription factors but analyses of a limited number of them have been reported so far. We have characterized the expression and the function of a member of Dof proteins of Arabidopsis. The GUS reporter gene under the control of the promoter of the Dof gene was expressed in the precursor cells of vasculature, procambium, in embryo, leaf primordia and root tips. Overexpression of the Dof gene caused the interruption of vascular network in cotyledons and true leaves. In severe cases, the overexpressing plants developed curled-up leaves. These results suggest the involvement of the Dof protein in vascular development in Arabidopsis.

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The light irradiation strongly inhibits growth of mesocotyl in dark-grown maize seedlings. We previously reported that white-light illumination caused a decrease in the contents of water and reduced form glutathione (GSH) in maize mesocotyls, suggesting their possible roles in the growth inhibition by light. In the present study, we examined effects of humidity and the GSH synthesis inhibitor BSO on the growth and GSH levels in maize mesocotyls. Under high humidity conditions in closed chambers, BSO (200 μM) caused a 25-33% growth inhibition and 37-45% decrease in GSH levels in 4-day-old mesocotyls. However, under these conditions, light caused very little growth inhibition in the presence or absence of BSO. These results suggested that water rather than GSH contents has a critical role in the growth inhibition of mesocotyls by light. GSH level might be changed as a result of water loss or concomitant cell damage by light.

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It has reported that the Brassinosteroids (BRs) function as a positive regulator of photomorphogenesis unexpectedly. To understand true functions of BRs, we analyzed expression levels of BR-related 4 genes (DWF4,BR6ox2,BR6ox1and SAUR-AC1) by real-time-quantitative (RTQ)-PCR in Arabidopsis etiolated seedlings. An etiolated seedling of Arabidopsis thaliana. consists of a long hypocotyl, a hook, and closed cotyledons. When the seedlings were exposed to light, the hypocotyl elongation was inhibited. At the same time, the hook started to unfold and cotyledons started to develop 3-6 hours after the treatment. Prior to the hook unfolding, expressions of all the four genes were strongly induced. In cotyledons, the expression of BR6ox2, DWF4, SAUR-AC1 were activated throughout 24hours. These results suggested that the hook opening and cotyledon development were induced by the BRs synthesized de novo. On the other hand, hypocotyls elongation may be controlled in more complex regulatory manners.

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Even after various physiological experiments, the molecular mechanism of auxin signaling in monocotyledonous plants remained unclear. To understand the function and mechanism of auxin signaling in rice, we focused on the IAA gene, a well-studied gene in Arabidopsis that serves as a negative regulator of auxin signaling. We found 24 IAA gene family members in the rice genome. OsIAA3 is one of the members whose expression is rapidly increased in response to auxin. We produced transgenic rice harboring mOsIAA3-GR, which can overproduce mutant OsIAA3 protein containing an amino acid change in domain II to cause a gain-of-function phenotype by treatment with dexamethasone. The transgenic rice was insensitive to auxin and gravitropic stimuli, and exhibited short leaf blades, reduced crown root formation, and abnormal cell arrangement in shoot-apical meristem. These results suggest that auxin is important for rice development and its signaling is mediated by the IAA genes in rice.

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Plant hormones have been known as signal compounds which regulate various responses at a low concentration in plants. To reveal the system, endogenous level of them had been quantified mainly by using GC-ESI-MS. Recently, microanalysis by using LC-ESI-MS/MS have been carried out frequently. In this method, samples do not require complicated purification and derivatization that GC-EI-MS requires. However, because ionization efficiency in LC-ESI-MS/MS method is susceptible to impurities, it requires suitable purification.
Our objective is that establishment of method for comprehensive analysis of all plant hormones. Here we report the method for analysis of gibberellin, abscisic acid, indole-3-acetic acid, jasmonic acid and salycilic acid. In our method for each hormone, required amount of plant material is 1/1000 to 1/10 to that of GC-EI-MS analysis and it requires no HPLC purification.
We will also report the analysis of other hormones and the comprehensive analysis from 100 mg of plant material.

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Photoreceptors, phytochromes and cryptochromes regulate hypocotyl growth under specific conditions by suppressing negative-gravitropism, modulating phototropism and inhibiting elongation. Although those effects seem to be partially caused via the regulation of the phytohormone auxin, the underlying molecular mechanisms are still poorly understood. Here we demonstrate that photoreceptors in Arabidopsis have at least two distinct effects: the inhibition of straight growth of hypocotyl depending on the ABC-type auxin transporter PGP19 and the induction of differential growth of hypocotyl independently of PGP19. Our genetic and gene-expression analyses reveal that the components involved in auxin transport, PGP19, is the suppressor of the straight growth in hypocotyl, and that activation of phytochromes and cryptochromes reduce the PGP19 expression and suppresses the basipetal auxin transport in hypocotyls. These results suggest that the control of auxin transport by phytochromes and cryptochromes is a critical component of the regulation of hypocotyl growth in response to light.

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The 6b gene is one of the tumourigenic genes of Agrobacterium tumefaciens, and causes morphological alterations, and reduced polar auxin transport. To investigate the relationship between endogenous auxin localization and cotyledonous morphology, we introduced to tobacco the AK-6b gene under the control of dexamethasone (Dex) inducible promoter. The seeds of T1 generation were sowed on MS medium containing Dex, and the seedlings were collected over time. Tissue sections were made and subjected to anatomical study or treated with the monoclonal antibody against indoleacetic acid (IAA). Analysis of the transverse sections indicated that the morphological alteration was recognized on the abaxial side of the cotyledons at 7 days after sowing. IAA was found to be equally distributed over cotyledons as long as 5 days. However, preferential localization was recognized on the abaxial side at 6-7 days. Therefore, it is suggested that the morphological alterations and the auxin localization are closely associated.

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Plant hormones play an important role as signaling molecules in the regulation of almost all phases of plant development, from seed germination to senescence. They regulate expression of genes via each signal transduction systems, and in most cases they mutually regulate the signaling and metabolic systems between the hormones. Such complicated regulatory systems enable plant to grow and develop normally. To understand the fine regulatory systems at molecular and hormonal levels, we have established a method for high-throughput analysis of major plant hormones, namely, cytokinins, auxins, abscisic acid, and gibberellins. Our method needs 10 to 100 mg fresh weight of plant tissues for determination and enables us to analyze 96 samples at a time. Using our method, we started to analyze FOX hunting Arabidopsis lines overexpressing rice full-length cDNA. We will present the analyzed data and discuss the correlation between the morphological phenotypes of the FOX lines and hormone profiles.

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