The cytochrome P450 CYP77A4 is involved in auxin-mediated patterning of the Arabidopsis thaliana embryo.

Metabolism often plays an important role in developmental control, in addition to supporting basal physiological requirements. However, our understanding of this interaction remains limited. Here, we performed quantitative phenome analysis of Arabidopsis thaliana cytochrome P450 mutants to identify a novel interaction between development and metabolism. We found that cyp77a4 mutants exhibit specific defects in cotyledon development, including asymmetric positioning and cup-shaped morphology, which could be rescued by introducing the CYP77A4 gene. Microscopy revealed that the abnormal patterning was detected at least from the 8-cell stage of the cyp77a4 embryos. We next analysed auxin distribution in mutant embryos, as the phenotypes resembled those of auxin-related mutants. We found that the auxin response pattern was severely perturbed in the cyp77a4 embryos owing to an aberrant distribution of the auxin efflux carrier PIN1. CYP77A4 intracellularly localised to the endoplasmic reticulum, which is consistent with the notion that this enzyme acts as an epoxidase of unsaturated fatty acids in the microsomal fraction. We propose that the CYP77A4-dependent metabolic pathway is an essential element for the establishment of polarity in plant embryos.

Regulation of Sugar and Storage Oil Metabolism by Phytochrome during De-etiolation.

Exposure of dark-grown (etiolated) seedlings to light induces the heterotrophic-to-photoautotrophic transition (de-etiolation) processes, including the formation of photosynthetic machinery in the chloroplast and cotyledon expansion. Phytochrome is a red (R)/far-red (FR) light photoreceptor that is involved in the various aspects of de-etiolation. However, how phytochrome regulates metabolic dynamics in response to light stimulus has remained largely unknown. In this study, to elucidate the involvement of phytochrome in the metabolic response during de-etiolation, we performed widely targeted metabolomics in Arabidopsis (Arabidopsis thaliana) wild-type and phytochrome A and B double mutant seedlings de-etiolated under R or FR light. The results revealed that phytochrome had strong impacts on the primary and secondary metabolism during the first 24 h of de-etiolation. Among those metabolites, sugar levels decreased during de-etiolation in a phytochrome-dependent manner. At the same time, phytochrome upregulated processes requiring sugars. Triacylglycerols are stored in the oil bodies as a source of sugars in Arabidopsis seedlings. Sugars are provided from triacylglycerols through fatty acid ß-oxidation and the glyoxylate cycle in glyoxysomes. We examined if and how phytochrome regulates sugar production from oil bodies. Irradiation of the etiolated seedlings with R and FR light dramatically accelerated oil body mobilization in a phytochrome-dependent manner. Glyoxylate cycle-deficient mutants not only failed to mobilize oil bodies but also failed to develop thylakoid membranes and expand cotyledon cells upon exposure to light. Hence, phytochrome plays a key role in the regulation of metabolism during de-etiolation.

Analysis of carbon flow at the metabolite level reveals that starch synthesis from hexose is a limiting factor in a high-yielding rice cultivar.

Understanding the limiting factors of grain filling is essential for the further improvement of grain yields in rice (Oryza sativa). The relatively slow grain growth of the high-yielding cultivar 'Momiroman' is not improved by increasing carbon supply, and hence low sink activity (i.e. the metabolic activity of assimilate consumption/storage in sink organs) may be a limiting factor for grain filling. However, there is no metabolic evidence to corroborate this hypothesis, partly because there is no consensus on how to define and quantify sink activity. In this study, we investigated the carbon flow at a metabolite level from photosynthesis in leaves to starch synthesis in grains of three high-yielding cultivars using the stable isotope 13C. We found that a large amount of newly fixed carbon assimilates in Momiroman was stored as hexose instead of being converted to starch. In addition, the activity of ADP-glucose pyrophosphorylase and the expression of AGPS2b, which encodes a subunit of the ADP-glucose pyrophosphorylase enzyme, were both lower in Momiroman than in the other two cultivars in grains in superior positions on panicle branches. Hence, slower starch synthesis from hexose, which is partly explained by the low expression level of AGPS2b, may be the primary metabolic reason for the lower sink activity observed in Momiroman.

Development of a Pteris vittata L. compound database by widely targeted metabolomics profiling.

The objective of this work was the development of a detailed, extensive and reliable database of the metabolomes of P. vittata. Using an ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry system (UPLC-QqQ-MS/MS) and based on the knowledge of retention time and mass spectral characteristics of an in-house collection of authentic standards, we screened for the presence of a large collection of natural compounds. The database represents 359 authenticated metabolites, comprising 220 primary and 139 secondary metabolites (70 flavonoids, 16 phenylpropanoic acid derivatives, five coumarins, two stilbenoids, 14 benzoic acids, nine phenols, 20 alkaloids and three terpenoids). Comparison of the accumulation of these compounds in two tissues showed that the aerial parts were enriched in flavonols, whereas the subterranean parts were enriched in anthocyanins. The comprehensive database developed here will be beneficial in improving the understanding of the chemical basis of plant therapeutic profile using multivariate analysis, with a particular example of antioxidant activity.

Comprehensive Metabolite Profiling in Genetic Resources of Garlic (Allium sativum L.) Collected from Different Geographical Regions.

Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits.

Identification of a Unique Type of Isoflavone O-Methyltransferase, GmIOMT1, Based on Multi-Omics Analysis of Soybean under Biotic Stress.

Isoflavonoids are commonly found in leguminous plants. Glycitein is one of the isoflavones produced by soybean. The genes encoding the enzymes in the isoflavone biosynthetic pathway have mostly been identified and characterized. However, the gene(s) for isoflavone O-methyltransferase (IOMT), which catalyzes the last step of glycitein biosynthesis, has not yet been identified. In this study, we conducted multi-omics analyses of fungal-inoculated soybean and indicated that glycitein biosynthesis was induced in response to biotic stress. Moreover, we identified a unique type of IOMT, which participates in glycitein biosynthesis. Soybean seedlings were inoculated with Aspergillus oryzae or Rhizopus oligosporus and sampled daily for 8 d. Multi-omics analyses were conducted using liquid chromatography-tandem mass spectrometry and RNA sequencing. Metabolome analysis revealed that glycitein derivatives increased following fungal inoculation. Transcriptome co-expression analysis identified two candidate IOMTs that were co-expressed with the gene encoding flavonoid 6-hydroxylase (F6H), the key enzyme in glycitein biosynthesis. The enzymatic assay of the two IOMTs using respective recombinant proteins showed that one IOMT, named as GmIOMT1, produced glycitein. Unlike other IOMTs, GmIOMT1 belongs to the cation-dependent OMT family and exhibited the highest activity with Zn2+ among cations tested. Moreover, we demonstrated that GmIOMT1 overexpression increased the levels of glycitein derivatives in soybean hairy roots when F6H was co-expressed. These results strongly suggest that GmIOMT1 participates in inducing glycitein biosynthesis in response to biotic stress.

Morphological characterization of domatium development in Callicarpa saccata.

BACKGROUND AND AIMS: Domatia are plant structures within which organisms reside. Callicarpa saccata (Lamiaceae) is the sole myrmecophyte, or 'ant plant', that develops foliar (leaf-borne) myrmeco-domatia in this genus. In this work we examined domatium development in C. saccata to understand the developmental processes behind pouch-like domatia. METHODS: Scanning electron microscopy, sectioning and microcomputed tomography were carried out to compare the leaves of C. saccata with those of the closely related but domatia-less myrmecophyte Callicarpa subaequalis, both under cultivation without ants. KEY RESULTS: Callicarpa saccata domatia are formed as a result of excess cell proliferation at the blade/petiole junctions of leaf primordia. Blade/petiole junctions are important meristematic sites in simple leaf organogenesis. We also found that the mesophyll tissue of domatia does not clearly differentiate into palisade and spongy layers. CONCLUSIONS: Rather than curling of the leaf margins, a perturbation of the normal functioning of the blade/petiole junction results in the formation of domatium tissue. Excess cell proliferation warps the shape of the blade and disturbs the development of the proximal-distal axis. This process leads to the generation of distinct structures that facilitate interaction between C. saccata and ants.

Syringic Acid Alleviates Cesium-Induced Growth Defect in Arabidopsis.

Syringic acid, a phenolic compound, serves a variety of beneficial functions in cells. Syringic acid increases in plants in response to cesium, and exogenous application of syringic acid resulted in a significant attenuation of cesium-induced growth defects in Arabidopsis. In addition, cesium or syringic acid application to plants also resulted in increased lignin deposition in interfascicular fibers. To better understand the role of lignin and syringic acid in attenuating cesium-induced growth defects, two mutants for Arabidopsis REDUCED EPIDERMAL FLUORESCENE 4 (REF4) and fourteen laccase mutants, some of which have lower levels of lignin, were evaluated for their response to cesium. These mutants responded differently to cesium stress, compared to control plants, and the application of syringic acid alleviated cesium-induced growth defects in the laccase mutants but not in the ref4 mutants. These findings imply that lignin plays a role in cesium signaling but the attenuation of cesium stress defects by syringic acid is mediated by regulatory components of lignin biosynthesis and not lignin biosynthesis itself. In contrast, syringic acid did not alleviate any low potassium-induced growth defects. Collectively, our findings provide the first established link between lignin and cesium stress via syringic acid in plants.

Metabolome-Based Discrimination Analysis of Shallot Landraces and Bulb Onion Cultivars Associated with Differences in the Amino Acid and Flavonoid Profiles.

Shallot landraces and varieties are considered an important genetic resource for Allium breeding due to their high contents of several functional metabolites. Aiming to provide new genetic materials for the development of a novel bulb onion cultivar derived from intraspecific hybrids with useful agronomic traits from shallots, the metabolic profiles in the bulbs of 8 Indonesian shallot landraces and 7 short-day and 3 long-day bulb onion cultivars were established using LC-Q-TOF-MS/MS. Principal component analysis, partial least squares discriminant analysis, and dendrogram clustering analysis showed two major groups; group I contained all shallot landraces and group II contained all bulb onion cultivars, indicating that shallots exhibited a distinct metabolic profile in comparison with bulb onions. Variable importance in the projection and Spearman's rank correlation indicated that free and conjugated amino acids, flavonoids (especially metabolites having flavonol aglycone), and anthocyanins, as well as organic acids, were among the top metabolite variables that were highly associated with shallot landraces. The absolute quantification of 21 amino acids using conventional HPLC analysis showed high contents in shallots rather than in bulb onions. The present study indicated that shallots reprogrammed their metabolism toward a high accumulation of amino acids and flavonoids as an adaptive mechanism in extremely hot tropical environments.

Effects of Thiosulfate as a Sulfur Source on Plant Growth, Metabolites Accumulation and Gene Expression in Arabidopsis and Rice.

Plants are considered to absorb sulfur from their roots in the form of sulfate. In bacteria like Escherichia coli, thiosulfate is a preferred sulfur source. It is converted into cysteine (Cys). This transformation consumes less NADPH and ATP than sulfate assimilation into Cys. In Saccharomyces cerevisiae, thiosulfate promoted growth more than sulfate. In the present study, the availability of thiosulfate, the metabolite transformations and gene expressions it induces were investigated in Arabidopsis and rice as model dicots and monocots, respectively. In Arabidopsis, the thiosulfate-amended plants had lower biomass than those receiving sulfate when sulfur concentrations in the hydroponic medium were above 300 µM. In contrast, rice biomass was similar for plants raised on thiosulfate and sulfate at 300 µM sulfur. Therefore, both plants can use thiosulfate but it is a better sulfur source for rice. In both plants, thiosulfate levels significantly increased in roots following thiosulfate application, indicating that the plants absorbed thiosulfate into their root cells. Thiosulfate is metabolized in plants by a different pathway from that used for sulfate metabolism. Thiosulfate increases plant sulfide and cysteine persulfide levels which means that plants are in a more reduced state with thiosulfate than with sulfate. The microarray analysis of Arabidopsis roots revealed that 13 genes encoding Cys-rich proteins were upregulated more with thiosulfate than with sulfate. These results together with those of the widely targeted metabolomics analysis were used to proposes a thiosulfate assimilation pathway in plants.

Metabolome-based discrimination of chrysanthemum cultivars for the efficient generation of flower color variations in mutation breeding.

INTRODUCTION: The color variations of ornamental flowers are often generated by ion-beam and gamma irradiation mutagenesis. However, mutation rates differ significantly even among cultivars of the same species, resulting in high cost and intensive labor for flower color breeding. OBJECTIVES: We aimed to establish a metabolome-based strategy to identify biomarkers and select promising parental lines with high mutation rates using Chrysanthemum as the case study. METHODS: The mutation rates associated with flower color were measured in 10 chrysanthemum cultivars with pink, yellow, or white flowers after soft X-ray irradiation at the floret-formation stage. The metabolic profiles of the petals of these cultivars were clarified by widely targeted metabolomics and targeted carotenoid analysis using liquid chromatography-tandem quadrupole mass spectrometry. Metabolome and carotenoid data were subjected to an un-supervised principal component analysis (PCA) and a supervised logistic regression with least absolute shrinkage and selection operator (LASSO). RESULTS: The PCA of the metabolic profile data separated chrysanthemum cultivars according to flower color rather than mutation rates. By contrast, logistic regression with LASSO generated a discrimination model to separate cultivars into two groups with high or low mutation rates, and selected 11 metabolites associated with mutation rates that can be biomarkers candidates for selecting parental lines for mutagenesis. CONCLUSION: This metabolome-based strategy to identify metabolite markers for mutation rates associated with flower color might be applied to other ornamental flowers to accelerate mutation breeding for generating new cultivars with a wider range of flower colors.

Interspecific Differences in the Larval Performance of Pieris Butterflies (Lepidoptera: Pieridae) Are Associated with Differences in the Glucosinolate Profiles of Host Plants.

The tremendous diversity of plants and herbivores has arisen from a coevolutionary relationship characterized by plant defense and herbivore counter adaptation. Pierid butterfly species feed on Brassicales plants that produce glucosinolates as a chemical deterrent against herbivory. In turn, the larvae of pierids have nitrile specifier proteins (NSPs) that are expressed in their gut and disarm glucosinolates. Pierid butterflies are known to have diversified in response to glucosinolate diversification in Brassicales. Therefore, each pierid species is expected to have a spectrum of host plants characterized by specific glucosinolate profiles. In this study, we tested whether the larval performance of different Pieris species, a genus in Pieridae (Lepidoptera: Pieridae), was associated with plant defense traits of putative host plants. We conducted feeding assays using larvae of three Pieris species and 10 species of the Brassicaceae family possessing different leaf physical traits and glucosinolate profile measurements. The larvae of Pieris rapae responded differently in the feeding assays compared with the other two Pieris species. This difference was associated with differences in glucosinolate profiles but not with variations in physical traits of the host plants. This result suggests that individual Pieris species are adapted to a subset of glucosinolate profiles within the Brassicaceae. Our results support the idea that the host ranges of Pieris species depend on larval responses to glucosinolate diversification in the host species, supporting the hypothesis of coevolution between butterflies and host plants mediated by the chemical arms race.

Genetic Variation for Seed Metabolite Levels in Brachypodium distachyon.

Metabolite composition and concentrations in seed grains are important traits of cereals. To identify the variation in the seed metabolotypes of a model grass, namely Brachypodium distachyon, we applied a widely targeted metabolome analysis to forty inbred lines of B. distachyon and examined the accumulation patterns of 183 compounds in the seeds. By comparing the metabolotypes with the population structure of these lines, we found signature metabolites that represent different accumulation patterns for each of the three B. distachyon subpopulations. Moreover, we found that thirty-seven metabolites exhibited significant differences in their accumulation between the lines Bd21 and Bd3-1. Using a recombinant inbred line (RIL) population from a cross between Bd3-1 and Bd21, we identified the quantitative trait loci (QTLs) linked with this variation in the accumulation of thirteen metabolites. Our metabolite QTL analysis illustrated that different genetic factors may presumably regulate the accumulation of 4-pyridoxate and pyridoxamine in vitamin B6 metabolism. Moreover, we found two QTLs on chromosomes 1 and 4 that affect the accumulation of an anthocyanin, chrysanthemin. These QTLs genetically interacted to regulate the accumulation of this compound. This study demonstrates the potential for metabolite QTL mapping in B. distachyon and provides new insights into the genetic dissection of metabolomic traits in temperate grasses.

Primary Metabolism during Biosynthesis of Secondary Wall Polymers of Protoxylem Vessel Elements.

Xylem vessels, the water-conducting cells in vascular plants, undergo characteristic secondary wall deposition and programmed cell death. These processes are regulated by the VASCULAR-RELATED NAC-DOMAIN (VND) transcription factors. Here, to identify changes in metabolism that occur during protoxylem vessel element differentiation, we subjected tobacco (Nicotiana tabacum) BY-2 suspension culture cells carrying an inducible VND7 system to liquid chromatography-mass spectrometry-based wide-target metabolome analysis and transcriptome analysis. Time-course data for 128 metabolites showed dynamic changes in metabolites related to amino acid biosynthesis. The concentration of glyceraldehyde 3-phosphate, an important intermediate of the glycolysis pathway, immediately decreased in the initial stages of cell differentiation. As cell differentiation progressed, specific amino acids accumulated, including the shikimate-related amino acids and the translocatable nitrogen-rich amino acid arginine. Transcriptome data indicated that cell differentiation involved the active up-regulation of genes encoding the enzymes catalyzing fructose 6-phosphate biosynthesis from glyceraldehyde 3-phosphate, phosphoenolpyruvate biosynthesis from oxaloacetate, and phenylalanine biosynthesis, which includes shikimate pathway enzymes. Concomitantly, active changes in the amount of fructose 6-phosphate and phosphoenolpyruvate were detected during cell differentiation. Taken together, our results show that protoxylem vessel element differentiation is associated with changes in primary metabolism, which could facilitate the production of polysaccharides and lignin monomers and, thus, promote the formation of the secondary cell wall. Also, these metabolic shifts correlate with the active transcriptional regulation of specific enzyme genes. Therefore, our observations indicate that primary metabolism is actively regulated during protoxylem vessel element differentiation to alter the cell's metabolic activity for the biosynthesis of secondary wall polymers.

Autopolyploidization, geographic origin, and metabolome evolution in Arabidopsis thaliana.

PREMISE OF THE STUDY: Autopolyploidy, or whole-genome duplication, is a recurrent phenomenon in plant evolution. Its existence can be inferred from the presence of massive levels of genetic redundancy revealed by comparative plant phylogenomics. Whole-genome duplication is theoretically associated with evolutionary novelties such as the development of new metabolic reactions and therefore contributes to the evolution of new plant metabolic profiles. However, very little is yet known about the impact of autopolyploidy on the metabolism of recently formed autopolyploids. This study provides a better understanding of the relevance of this evolutionary process. METHODS: In this study, we compared the metabolic profiles of wild diploids, wild autotetraploids, and artificial autotetraploids of Arabidopsis thaliana using targeted ultra-high performance liquid chromatography-triple quadrupole- mass spectrometry (UPLC-QqQ-MS) metabolomics. KEY RESULTS: We found that wild and artificial A. thaliana autotetraploids display different metabolic profiles. Furthermore, wild autotetraploids display unique metabolic profiles associated with their geographic origin. CONCLUSIONS: Autopolyploidy might help plants adapt to challenging environmental conditions by allowing the evolution of novel metabolic profiles not present in the parental diploids. We elaborate on the causes and consequences leading to these distinct profiles.

Chemical Assignment of Structural Isomers of Sulfur-Containing Metabolites in Garlic by Liquid Chromatography-Fourier Transform Ion Cyclotron Resonance-Mass Spectrometry.

BACKGROUND: The chemical assignment of metabolites is crucial to understanding the relation between food composition and biological activity. OBJECTIVE: This study was designed to detect and chemically assign sulfur-containing metabolites by using LC-Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) in Allium plants. METHODS: Ultrahigh resolution (>250,000 full width at half-maximum) and mass accuracy (<1 mDa) by FTICR-MS allowed us to distinguish ions containing sulfur isotopes ((32)S and (34)S). RESULTS: Putative 69 S-containing monoisotopic ions (S-ions) were extracted from the metabolome data of onion (Allium cepa), green onion (Allium fistulosum), and garlic (Allium sativum) on the basis of theoretical mass differences between (32)S-ions and their (34)S-substituted counterparts and on the natural abundance of (34)S. Eight S-ions were chemically assigned by using the reference data according to the guidelines of the Metabolomics Standards Initiative. Three ions detected in garlic were assigned as derived from the isomers γ-glutamyl-S-1-propenylcysteine and γ-glutamyl-S-2-propenylcysteine and as S-2-propenylmercaptoglutathione on the basis of differences in key product ions identified in reference tandem MS spectra. CONCLUSION: The ability to discriminate between such geometric isomers will be extremely useful for the chemical assignment of unknown metabolites in MS-based metabolomics.

Determination of growth stages and metabolic profiles in Brachypodium distachyon for comparison of developmental context with Triticeae crops.

Brachypodium distachyon is an emerging model plant for studying biological phenomena in temperate grasses. Study of the growth scale is essential to analyse spatio-temporal changes in molecular factors throughout the life cycle. For sensitive and robust staging based on morphology in B. distachyon, we demonstrated the utility of the BBCH (Biologische Bundesanstalt, Bundessortenamt and CHemical industry) scale, which is comparable to the Zadoks scale conventionally used for Triticeae crops. We compared the chronological progression of B. distachyon accessions Bd21 and Bd3-1, in addition to the progression of Chinese Spring wheat. The comparison of growth stages illustrates the morphological similarities and differences in the timing of life cycle events. Furthermore, we compared metabolite accumulation patterns across different growth stages and across different stress conditions using a widely targeted metabolome analysis. Metabolic profiling determined commonalities and specificities in chemical properties that were dependent on organisms, growth stages and/or stress conditions. Most metabolites accumulated equivalently in B. distachyon and wheat. This qualitative similarity indicated the superiority of B. distachyon as a model for Triticeae crops. The growth scale of B. distachyon should provide a conceptual framework for comparative analysis and for knowledge integration between this model grass and crops in the Pooideae subfamily.

Disarming the jasmonate-dependent plant defense makes nonhost Arabidopsis plants accessible to the American serpentine leafminer.

Here, we analyzed the interaction between Arabidopsis (Arabidopsis thaliana) and the American serpentine leafminer (Liriomyza trifolii), an important and intractable herbivore of many cultivated plants. We examined the role of the immunity-related plant hormone jasmonate (JA) in the plant response and resistance to leafminer feeding to determine whether JA affects host suitability for leafminers. The expression of marker genes for the JA-dependent plant defense was induced by leafminer feeding on Arabidopsis wild-type plants. Analyses of JA-insensitive coi1-1 mutants suggested the importance of JA in the plant response to leafminer feeding. The JA content of wild-type plants significantly increased after leafminer feeding. Moreover, coi1-1 mutants showed lower feeding resistance against leafminer attack than did wild-type plants. The number of feeding scars caused by inoculated adult leafminers in JA-insensitive coi1-1 mutants was higher than that in wild-type plants. In addition, adults of the following generation appeared only from coi1-1 mutants and not from wild-type plants, suggesting that the loss of the JA-dependent plant defense converted nonhost plants to accessible host plants. Interestingly, the glucosinolate-myrosinase defense system may play at most a minor role in this conversion, indicating that this major antiherbivore defense of Brassica species plants probably does not have a major function in plant resistance to leafminer. Application of JA to wild-type plants before leafminer feeding enhanced feeding resistance in Chinese cabbage (Brassica rapa), tomato (Solanum lycopersicum), and garland chrysanthemum (Chrysanthemum coronarium). Our results indicate that JA plays an important role in the plant response and resistance to leafminers and, in so doing, affects host plant suitability for leafminers.

Os-GIGANTEA confers robust diurnal rhythms on the global transcriptome of rice in the field.

The circadian clock controls physiological traits such as flowering time, photosynthesis, and growth in plants under laboratory conditions. Under natural field conditions, however, little is known about the significance of the circadian clock in plants. By time-course transcriptome analyses of rice (Oryza sativa) leaves, using a newly isolated rice circadian clock-related mutant carrying a null mutation in Os-GIGANTEA (Os-GI), we show here that Os-GI controlled 75% (false discovery rate = 0.05) of genes among 27,201 genes tested and was required for strong amplitudes and fine-tuning of the diurnal rhythm phases of global gene expression in the field. However, transcripts involved in primary metabolism were not greatly affected by osgi. Time-course metabolome analyses of leaves revealed no trends of change in primary metabolites in osgi plants, and net photosynthetic rates and grain yields were not affected. By contrast, some transcripts and metabolites in the phenylpropanoid metabolite pathway were consistently affected. Thus, net primary assimilation of rice was still robust in the face of such osgi mutation-related circadian clock defects in the field, unlike the case with defects caused by Arabidopsis thaliana toc1 and ztl mutations in the laboratory.

Effects of different colors of light on melatonin suppression and expression analysis of Aanat1 and melanopsin in the eye of a tropical damselfish.

Ocular melatonin production exhibits a daily rhythm with a decrease during photophase and an increase during scotophase (nocturnal pattern) in teleost fish due to day-night changes in the activity of the rate-limiting melatonin synthesizing enzyme arylalkylamine N-acetyltransferase (AANAT). Acute light exposure during scotophase suppresses AANAT activity and melatonin production in the eyes, suggesting that external light signals are a principal regulator of ocular melatonin synthesis. To better understand the photic regulation of ocular melatonin synthesis in teleost fish, this study sought to characterize the effect of light on ocular melatonin synthesis in the sapphire devil Chrysiptera cyanea, which shows a nocturnal pattern and light-induced inhibition of ocular melatonin production during scotophase. Exposure to three different wavelengths of light (half-peak bandwidth=435-475 nm with a peak of 455 nm, 495-565 nm with a peak of 530 nm, and 607-647 nm with a peak of 627 nm for the blue, green, and red LEDs) for 2h during scotophase resulted in the blue wavelength significantly decreasing ocular melatonin content within 30 min after light exposure. This result clearly indicates that the effective range of visible light on ocular melatonin suppression is distributed within the wavelengths of blue light and that a blue light-sensitive opsin is involved in ocular melatonin suppression in the fish. A PCR-based cloning method revealed the expression of melanopsin, a putative blue light-sensitive nonvisual opsin, in the eyes. Furthermore, in situ hybridization using the sapphire devil Aanat1 and melanopsin RNA probes showed mRNA expressions of both genes in the inner nuclear and ganglion cell layer of the fish retina. These results suggest that melanopsin is a possible candidate photoreceptor involved in ocular melatonin suppression by an external light signal in the sapphire devil.