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This paper proposes a current control method for discontinuous current mode (DCM) in order to achieve the same control performance as continuous current mode (CCM) in a boost converter. By utilizing the duty ratio at the previous calculation period to compensate for a DCM nonlinearity, the controller, which is designed for CCM, can also be used in DCM. In the frequency analysis, the cutoff frequency of the proposed DCM current control agrees exactly to the design value, which is 2 kHz, whereas the cutoff frequency of the conventional DCM current control results in high error of 47.5%. In the current step response experiment with a 360-W prototype and the switching frequency of 20 kHz, the experimental DCM current response almost agrees with the conventional CCM current response, which are 380-μs rise time for both CCM and DCM, 9% and 8% overshoot for CCM and DCM, respectively. Furthermore, the computation time of the proposed DCM current control is shorter 35% than the conventional DCM current control. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes a configuration of a single-phase voltage source inverter that features power decoupling capability. Generally, the converter connected to a single-phase grid employs bulky dc link capacitors such as electrolytic capacitors in order to decouple the power ripple with twice the frequency of the power supply. The power ripple in the proposed circuit is compensated by an active buffer with small capacitors. In this paper, the fundamental operations of the proposed converter are confirmed by experimental results. From the experimental results, the output current total harmonic distortion (THD) is 3.51%, the ratio of the input current is 14.3%, and the output power factor is over 99%. In addition, the volume of the proposed circuit is reduced by 61% when the carrier frequency is 64 kHz compared to that with a carrier frequency of 16 kHz. Finally, from an evaluation of the power density using Pareto front curves, the proposed circuit achieves high power density in comparison with the conventional circuit. [ABSTRACT FROM AUTHOR]

It has been brought to the attention of the publisher that an error appeared in the title of the above article. The title as it appears here is correct. We apologize for any inconvenience this error may have caused the author. [ABSTRACT FROM AUTHOR]

This paper proposes a new circuit configuration and a control scheme for a single-phase current-source inverter with a power decoupling circuit which is called as the active buffer. The proposed inverter achieves a low-dc-input voltage ripple and also provides a sinusoidal current that can achieve unity power factor, without large passive components in the dc bus such as smoothing inductors and electrolytic capacitors. These components are conventionally required in order to decouple the power pulsation caused by the single-phase power source. In this paper, the fundamental operations of the proposed inverter are demonstrated experimentally. From the experimental results, the input voltage ripple is 8.87%, and the output current total harmonic distortion is 4.24%. In addition, an output power factor of 99% and a maximum efficiency of 94.9% are obtained. Finally, it is confirmed that the maximum power densities of the conventional circuit and the proposed circuit are 2.75 kW/L at the switching frequency of 70 kHz and 4.86 kW/L at the switching frequency of 80 kHz, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Some decapod crustaceans release larvae from estuarine or coastal shores to coastal oceans. Decapodids (last-stage larvae) return home, settle, and metamorphose into juveniles I, which go through further instars. Several morphological characters degenerate or develop in response to lifestyle transitions. Using a burrow-dwelling callianassid shrimp, Nihonotrypaea harmandi, inhabiting an intertidal sandflat in a coastal boundary layer adjacent to coastal ocean, this study described morphological changes and drew inferences about states and processes in its early life history. Decapodid and juveniles were differentiated by linea thalassinica on carapace. In the laboratory, the decapodid stage lasted 3–6d. Given choice between sandy sediments from coastal ocean bed and adult habitat, decapodids exhibited no preference, suggesting broad receptiveness. The shortest durations of the juvenile-I, -II, and -III were estimated at 6d each. Starved decapodids normally metamorphosed into juveniles I, showing secondary lecithotrophy. The non-feeding state could be extended through the juvenile I (and possibly juvenile II), where the mean total lengths of shrimps reared in groups with food (diatoms) remained about 4.6mm. Post-settlement decapodids reared individually resumed feeding. The rostrum lengths in decapodids were ≥0.36mm on the initial two dates (Days 0 and 1), after which the mean values rapidly reduced to 0.30–0.36mm on Day 2 and below 0.30mm thereafter. The pereiopod exopods disappeared through the decapodid stage from four pairs to almost zero by Day 4. In the coastal ocean, no juveniles occurred, and almost all decapodids had rostrum lengths ≥0.30mm and 3 or 4 pereiopod exopods, suggesting their pre-settlement state. Of the smallest shrimps collected on the sandflat for their subsequent rearing there, 74% were estimated to be Day-0 or -1 decapodids based on their rostrum lengths. This and the laboratory experimental results suggest (1) the acquisition of competence for settlement by newly-metamorphosed decapodids while in the coastal ocean, which was nevertheless realized there and (2) their rapid transport by flood tidal currents from coastal ocean to sandflat. The newly-settled decapodids grew steadily at 0.2mmd−1 in total length. The reared juveniles reached the smallest adult size in 80d. The uropod expod changed from elliptical to sub-circular in shape markedly around the termination of the juvenile II or III, suggesting the acquisition of ventilating function for benthic life. Overall, the post-settlement shrimps can be staged by total-length ranges as 4–5.5mm for decapodids, 5.5–10mm for juveniles, and 10–20mm for sub-adults. [Copyright &y& Elsevier]

Most aerial parts of the plant body are products of the continuous activity of the shoot apical meristem (SAM). Leaves are the major component of the aerial plant body, and their temporal and spatial distribution mainly determines shoot architecture. Here we report the identification of the rice gene PLASTOCHRON3 ( PLA3)/ GOLIATH ( GO) that regulates various developmental processes including the rate of leaf initiation (the plastochron). PLA3/ GO encodes a glutamate carboxypeptidase, which is thought to catabolize small acidic peptides and produce small signaling molecules. pla3 exhibits similar phenotypes to pla1 and pla2– a shortened plastochron, precocious leaf maturation and rachis branch-to-shoot conversion in the reproductive phase. However, in contrast to pla1 and pla2, pla3 showed pleiotropic phenotypes including enlarged embryo, seed vivipary, defects in SAM maintenance and aberrant leaf morphology. Consistent with these pleiotropic phenotypes, PLA3 is expressed in the whole plant body, and is involved in plant hormone homeostasis. Double mutant analysis revealed that PLA1, PLA2 and PLA3 are regulated independently but function redundantly. Our results suggest that PLA3 modulates various signaling pathways associated with a number of developmental processes. [ABSTRACT FROM AUTHOR]

The plastochron, the time interval between the formation of two successive leaves, is an important determinant of plant architecture. We genetically and phenotypically investigated many-noded dwarf (mnd) mutants in barley. The mnd mutants exhibited a shortened plastochron and a decreased leaf blade length, and resembled previously reported plastochron1 (pla1), pla2, and pla3 mutants in rice. In addition, the maturation of mnd leaves was accelerated, similar to pla mutants in rice. Several barley mnd alleles were derived from three genes—MND1, MND4, and MND8. Although MND4 coincided with a cytochrome P450 family gene that is a homolog of rice PLA1, we clarified that MND1 and MND8 encode an N-acetyltransferase-like protein and a MATE transporter-family protein, which are respectively orthologs of rice GW6a and maize BIGE1 and unrelated to PLA2 or PLA3. Expression analyses of the three MND genes revealed that MND1 and MND4 were expressed in limited regions of the shoot apical meristem and leaf primordia, but MND8 did not exhibit a specific expression pattern around the shoot apex. In addition, the expression levels of the three genes were interdependent among the various mutant backgrounds. Genetic analyses using the double mutants mnd4mnd8 and mnd1mnd8 indicated that MND1 and MND4 regulate the plastochron independently of MND8, suggesting that the plastochron in barley is controlled by multiple genetic pathways involving MND1, MND4, and MND8. Correlation analysis between leaf number and leaf blade length indicated that both traits exhibited a strong negative association among different genetic backgrounds but not in the same genetic background. We propose that MND genes function in the regulation of the plastochron and leaf growth and revealed conserved and diverse aspects of plastochron regulation via comparative analysis of barley and rice. Author summary: The number of leaves produced during a plant's lifetime is major determinant of plant architecture and affects the efficiency of photosynthesis and crop productivity. The leaf number is dependent on the temporal pattern of leaf initiation at the shoot apical meristem, which is termed the plastochron. The genetic factors involved in plastochron regulation have been identified in several plant species. However, whether the functions of plastochron-related genes and their genetic pathways are universal or diversified among different plant species is unclear. In this study, we investigated many-noded dwarf (mnd) mutants in barley, which exhibited a shortened plastochron and a decreased leaf blade length. The mutant alleles used in this study were derived from three genes, MND4, MND1, and MND8, which encode a cytochrome P450 family protein, an N-acetyltransferase-like protein, and a MATE transporter-family protein, respectively. Phenotypic and expression analyses revealed that these three MND genes affect the leaf production rate and leaf maturation program, but their expression levels were interdependent. In addition, the plastochron and leaf growth are closely related but independently regulated. We also analyzed the expression patterns and knockout mutants of rice MND orthologs to clarify whether their biological functions are conserved in rice and barley. This study provides insight into the genetic mechanisms of plastochron control in grass species. [ABSTRACT FROM AUTHOR]

Background: Rice leaves consist of three distinct regions along a proximal-distal axis, namely the leaf blade, sheath, and blade-sheath boundary region. Each region has a unique morphology and function, but the genetic programs underlying the development of each region are poorly understood. To fully elucidate rice leaf development and discover genes with unique functions in rice and grasses, it is crucial to explore genome-wide transcriptional profiles during the development of the three regions. Results: In this study, we performed microarray analysis to profile the spatial and temporal patterns of gene expression in the rice leaf using dissected parts of leaves sampled in broad developmental stages. The dynamics in each region revealed that the transcriptomes changed dramatically throughout the progress of tissue differentiation, and those of the leaf blade and sheath differed greatly at the mature stage. Cluster analysis of expression patterns among leaf parts revealed groups of genes that may be involved in specific biological processes related to rice leaf development. Moreover, we found novel genes potentially involved in rice leaf development using a combination of transcriptome data and in situ hybridization, and analyzed their spatial expression patterns at high resolution. We successfully identified multiple genes that exhibit localized expression in tissues characteristic of rice or grass leaves. Conclusions: Although the genetic mechanisms of leaf development have been elucidated in several eudicots, direct application of that information to rice and grasses is not appropriate due to the morphological and developmental differences between them. Our analysis provides not only insights into the development of rice leaves but also expression profiles that serve as a valuable resource for gene discovery. The genes and gene clusters identified in this study may facilitate future research on the unique developmental mechanisms of rice leaves. [ABSTRACT FROM AUTHOR]

This paper proposes a control method for a dual active bridge (DAB) converter, which achieves both a reduction in the nonlinear transmission power error due to the dead‐time and a reduction in the inductor current with a three‐level operation. The nonlinear transmission power error is compensated by designing a zero current period in the inductor current with the three‐level operation. In addition, an inductor current reduction method for the three‐level operation is also proposed. In the nonlinear transmission power error compensation method, the inductor current is reduced by suppressing the circulating current by considering the zero‐current period to be the dead‐time. The validity of the proposed method is confirmed using a 2.0‐kW prototype. The experimental results show that the transmission power error is reduced by up to 85.1%. In addition, the inductor current is reduced by up to 64.1% and the loss is reduced by up to 58.6%. Moreover, the DC offset is eliminated by utilizing the voltage polarity reverse phenomenon in the voltage control. [ABSTRACT FROM AUTHOR]

Summary: Floods impede gas (O2 and CO2) exchange between plants and the environment. A mechanism to enhance plant gas exchange under water comprises gas films on hydrophobic leaves, but the genetic regulation of this mechanism is unknown. We used a rice mutant (dripping wet leaf 7, drp7) which does not retain gas films on leaves, and its wild‐type (Kinmaze), in gene discovery for this trait. Gene complementation was tested in transgenic lines. Functional properties of leaves as related to gas film retention and underwater photosynthesis were evaluated. Leaf Gas Film 1 (LGF1) was identified as the gene determining leaf gas films. LGF1 regulates C30 primary alcohol synthesis, which is necessary for abundant epicuticular wax platelets, leaf hydrophobicity and gas films on submerged leaves. This trait enhanced underwater photosynthesis 8.2‐fold and contributes to submergence tolerance. Gene function was verified by a complementation test of LGF1 expressed in the drp7 mutant background, which restored C30 primary alcohol synthesis, wax platelet abundance, leaf hydrophobicity, gas film retention, and underwater photosynthesis. The discovery of LGF1 provides an opportunity to better understand variation amongst rice genotypes for gas film retention ability and to target various alleles in breeding for improved submergence tolerance for yield stability in flood‐prone areas. [ABSTRACT FROM AUTHOR]

In the present, a power decoupling method without additional component is proposed for a dc to single-phase ac converter, which consists of a flying capacitor dc/dc converter (FCC) and the voltage source inverter (VSI). In particular, a small flying capacitor in the FCC is used for both a boost operation and a double-line-frequency power ripple reduction. Thus, the dc-link capacitor value can be minimized in order to avoid the use of a large electrolytic capacitor. In addition, component design, of, e.g., the boost inductor and the flying capacitor, is clarified when the proposed control is applied. Experiments were carried out using a 1.5-kW prototype in order to verify the validity of the proposed control. The experimental results revealed that the use of the proposed control reduced the dc-link voltage ripple by 74.5%, and the total harmonic distortion (THD) of the inverter output current was less than 5%. Moreover, a maximum system efficiency of 95.4% was achieved at a load of 1.1 kW. Finally, the high power density design is evaluated by the Pareto front optimization. The power densities of three power decoupling topologies, such as a boost topology, a buck topology, and the proposed topology are compared. As a result, the proposed topology achieves the highest power density (5.3 kW/dm3) among the topologies considered herein. [ABSTRACT FROM AUTHOR]

In several eudicot species, one copy of each member of the WUSCHEL-RELATED HOMEOBOX (WOX) gene family, WOX1 and WOX3, is redundantly or differentially involved in lateral leaf outgrowth, whereas only the WOX3 gene regulating the lateral domain of leaf development has been reported in grass. In this study, we show that a WOX3 gene, LEAF LATERAL SYMMETRY1 (LSY1), regulates lateral leaf development in a different manner ftom that of other duplicated paralogs of WOX3, NARROW LEAF2 (NAL2)/NAL3, in rice. A loss-of-function mutant of LSY1 exhibited an asymmetrical defect from early leaf development, which is different from a symmetric defect in a double loss-of-function mutant of NAL2/3, whereas the expression of both genes was observed in a similar domain in the margins of leaf primordia. Unlike NAL2/3, overexpression of LSY1 produced malformed leaves whose margins were curled adaxially. Expression domains and the level of adaxial/abaxial marker genes were affected in the LSY1-overexpressing plants, indicating that LSY1 is involved in regulation of adaxial-abaxial patterning at the margins of the leaf primordia. Additive phenotypes in some leaf traits of lsy1 nal2/3 triple mutants and the unchanged level of NAL2/3 expression in the lsy1 background suggested that LSY1 regulates lateral leaf development independently of NAL2/3. Our results indicated that all of the rice WOX3 genes are involved in leaf lateral outgrowth, but the functions of LSY1 and NAL2/3 have diverged. We propose that the function of WOX3 and the regulatory mode of leaf development in rice are comparable with those of WOX1/WOX3 in eudicot species. [ABSTRACT FROM AUTHOR]

Auxin is a fundamental plant hormone and its localization within organs plays pivotal roles in plant growth and development. Analysis of many Arabidopsis mutants that were defective in auxin biosynthesis revealed that the indole-3-pyruvic acid ( IPA) pathway, catalyzed by the TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS ( TAA) and YUCCA ( YUC) families, is the major biosynthetic pathway of indole-3-acetic acid ( IAA). In contrast, little information is known about the molecular mechanisms of auxin biosynthesis in rice. In this study, we identified a auxin-related rice mutant, fish bone ( fib). FIB encodes an orthologue of TAA genes and loss of FIB function resulted in pleiotropic abnormal phenotypes, such as small leaves with large lamina joint angles, abnormal vascular development, small panicles, abnormal organ identity and defects in root development, together with a reduction in internal IAA levels. Moreover, we found that auxin sensitivity and polar transport activity were altered in the fib mutant. From these results, we suggest that FIB plays a pivotal role in IAA biosynthesis in rice and that auxin biosynthesis, transport and sensitivity are closely interrelated. [ABSTRACT FROM AUTHOR]

Maintenance of organ separation is one of the essential phenomena for normal plant development. We have identified and analyzed ONION3 (ONI3), which is required for avoiding organ fusions in rice. Loss-of-function mutations of ONI3, which were identified as mutants with ectopic expression of KNOX genes in leaves and morphologically resembling KNOX overexpressors, showed abnormal organ fusions in developing shoots. The mutant seedlings showed fusions between neighboring organs and also within an organ; they stopped growing soon after germination and subsequently died. ONI3 was shown to encode an enzyme that is most similar to Arabidopsis HOTHEAD and is involved in biosynthesis of long-chain fatty acids. Expression analyses showed that ONI3 was specifically expressed in the outermost cell layer in the shoot apex throughout life cycle, and the oni3 mutants had an aberrant outermost cell layer. Our results together with previous studies suggest that long-chain fatty acids are required for avoiding organ fusions and promoting normal shoot development in rice. [ABSTRACT FROM PUBLISHER]

Summary The temporal and spatial control of meristem identity is a key element in plant development. To better understand the molecular mechanisms that regulate inflorescence and flower architecture, we characterized the rice aberrant panicle organization 2 ( apo2) mutant which exhibits small panicles with reduced number of primary branches due to the precocious formation of spikelet meristems. The apo2 mutants also display a shortened plastochron in the vegetative phase, late flowering, aberrant floral organ identities and loss of floral meristem determinacy. Map-based cloning revealed that APO2 is identical to previously reported RFL gene, the rice ortholog of the Arabidopsis LEAFY ( LFY) gene. Further analysis indicated that APO2/RFL and APO1, the rice ortholog of Arabidopsis UNUSUAL FLORAL ORGANS, act cooperatively to control inflorescence and flower development. The present study revealed functional differences between APO2/RFL and LFY. In particular, APO2/RFL and LFY act oppositely on inflorescence development. Therefore, the genetic mechanisms for controlling inflorescence architecture have evolutionarily diverged between rice (monocots) and Arabidopsis (eudicots). [ABSTRACT FROM AUTHOR]

Because plant reproductive development occurs only in adult plants, the juvenile-to-adult phase change is an indispensable part of the plant life cycle. We identified two allelic mutants, peter pan syndrome-1 (pps-1) and pps-2 , that prolong the juvenile phase in rice (Oryza sativa) and showed that rice PPS is an ortholog of Arabidopsis thaliana CONSTITUTIVE PHOTOMORPHOGENIC1. The pps-1 mutant exhibits delayed expression of miR156 and miR172 and the suppression of GA biosynthetic genes, reducing the GA3 content in this mutant. In spite of its prolonged juvenile phase, the pps-1 mutant flowers early, and this is associated with derepression of RAP1B expression in pps-1 plants independently of the Hd1 - Hd3a/RFT1 photoperiodic pathway. PPS is strongly expressed in the fourth and fifth leaves, suggesting that it regulates the onset of the adult phase downstream of MORI1 and upstream of miR156 and miR172. Its ability to regulate the vegetative phase change and the time of flowering suggests that rice PPS acquired novel functions during the evolution of rice/monocots. [ABSTRACT FROM AUTHOR]

Abstract: The adaxial–abaxial axis in leaf primordia is thought to be established first and is necessary for the expansion of the leaf lamina along the mediolateral axis. To understand axis information in leaf development, we isolated the adaxialized leaf1 (adl1) mutant in rice, which forms abaxially rolled leaves. adl1 leaves are covered with bulliform-like cells, which are normally distributed only on the adaxial surface. An adl1 double mutant with the adaxially snowy leaf mutant, which has albino cells that specifically appear in the abaxial mesophyll tissue, indicated that adl1 leaves show adaxialization in both epidermal and mesophyll tissues. The expression of HD-ZIPIII genes in adl1 mutant increased in mature leaves, but not in the young primordia or the SAM. This indicated that ADL1 may not be directly involved in determining initial leaf polarity, but rather is associated with the maintenance of axis information. ADL1 encodes a plant-specific calpain-like cysteine proteinase orthologous to maize DEFECTIVE KERNEL1. Furthermore, we identified intermediate and strong alleles of the adl1 mutant that generate shootless embryos and globular-arrested embryos with aleurone layer loss, respectively. We propose that ADL1 plays an important role in pattern formation of the leaf and embryo by promoting proper epidermal development. [Copyright &y& Elsevier]

This paper proposes a control strategy for matrix converters to reduce the torque ripple in the overmodulation range. In the overmodulation range, motor drive performance of matrix converters is deteriorated because of the output voltage saturation. In particular, the torque ripple which has lower frequency components than the input voltage frequency is remarkable. This paper presents a theoretical analysis of the causes of the torque ripple and the effect of the proposed control strategy. Experimental examinations including performance comparison with a trapezoidal wave modulation are carried out using a 400-V, 22-kW experimental system. The experimental results verify the validity of the theoretical analysis and confirm the effectiveness of the proposed control strategy for reducing the torque ripple. Furthermore, the harmonic distortion of the output current is also reduced compared with the trapezoidal wave modulation. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(4): 40–48, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20829 [ABSTRACT FROM AUTHOR]

Numerous genes are involved in the regulation of plant development, including those that regulate floral homeotic genes, We identified two recessive allelic rice mutants, open beak-1 ( opb-1) and opb-2, which exhibited pleiotropic defects in leaf morphogenesis, inflorescence architecture, and floral organ identity. Abnormal cell proliferation was observed in the leaves and spikelets, and ectopic or overexpression of several class 1 knox genes was detected; thus, the abnormal cell proliferation in opb mutants is probably caused by ectopic class 1 knox gene expression. The opb mutants also had defects in floral organ identity, resulting in the development of mosaic organs, including gluminous lodicules, staminoid lodicules, and pistiloid stamens. These results, together with the reduced expression of a class B gene, indicate that OPB positively regulates the expression of class B genes. Map-based cloning revealed that OPB encodes a transcription factor that is orthologous to the Arabidopsis JAGGED gene and is expressed in leaf primordia, inflorescence meristem, rachis branch meristems, floral meristem, and floral organ primordia. Taken together, our data suggest that the OPB gene affects cellular proliferation and floral organ identity through the regulation of class 1 knox genes and floral homeotic genes. [ABSTRACT FROM AUTHOR]

In this paper, a novel control method for a matrix converter is proposed. The proposed method is a PAM (Pulse Amplitude Modulation) control method based on a virtual AC/DC/AC conversion method. Output voltage amplitude is controlled by controlling a virtual DC link voltage with a virtual rectifier. Output frequency is controlled by a virtual inverter. First, the proposed method is explained. Next, the validity of the proposed method is confirmed through simulation and experiment using a 750-W prototype matrix converter. Moreover, various characteristics of the proposed method and conventional virtual AC/DC/AC method are compared through experiment. As a result of the experiment, it has been understood that total harmonic distortion of output current and common-mode voltage can be reduced compared with the case of using a conventional virtual AC/DC/AC conversion method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 88–96, 2009; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20601 [ABSTRACT FROM AUTHOR]

Abstract: We isolated flattened shoot meristem (fsm) mutants in rice that showed defective seedling growth and died in the vegetative phase. Since most fsm plants had flat and small shoot apical meristems (SAMs), we suggest that FSM is required for proper SAM maintenance. FSM encodes a putative ortholog of Arabidopsis FASCIATA1 (FAS1) that corresponds to the p150 subunit of chromatin assembly factor-1 (CAF-1). FSM is expressed patchily in tissues with actively dividing cells, suggesting a tight association of FSM with specific cell-cycle phases. Double-target in situ hybridization counterstained with cell-cycle marker genes revealed that FSM is expressed mainly in the G1 phase. In fsm, expressions of the two marker genes representing S- and G2- to M-phases were enhanced in SAM, despite a reduced number of cells in SAM, suggesting that S- and G2-phases are prolonged in fsm. In addition, developmental events in fsm leaves took place at the proper time, indicating that the temporal regulation of development occurs independently of the cell-cycle period. In contrast to the fasciated phenotype of Arabidopsis fas1, fsm showed size reduction of SAM. The opposite phenotypes between fsm and fas1 indicate that the SAM maintenance is regulated differently between rice and Arabidopsis. [Copyright &y& Elsevier]

During postembryonic development of higher plants, the shoot apical meristem produces lateral organs in a regular spacing (phyllotaxy) and a regular timing (plastochron). Molecular analysis of mutants associated with phyllotaxy and plastochron would greatly increase understanding of the developmental mechanism of plant architecture because phyllotaxy and plastochron are fundamental regulators of plant architecture. pla 1 of rice is not only a plastochron mutant showing rapid leaf initiation without affecting phyllotaxy, but also a heterochronic mutant showing ectopic shoot formation in the reproductive phase. Thus, pla1 provides a tool for analyzing the molecular basis of temporal regulation in leaf development. In this work, we isolated the PLA1 gene by map-based cloning. The identified PLA1 gene encodes a cytochrome P450, CYP78A11, which potentially catalyzes substances controlling plant development. PLA1 is expressed in developing leaf primordia, bracts of the panicle, and elongating internodes, but not in the shoot apical meristem. The expression pattern and mutant phenotype suggest that the PLA1 gene acting in developing leaf primordia affects the timing of successive leaf initiation and the termination of vegetative growth. [ABSTRACT FROM AUTHOR]