GA Deficiency Research Articles

Self-adaptively electronic transfer of ternary Ni3Ga0.8In0.2/SiO2 alloy catalysts toward enhancing selectivity hydrogenation

Non-noble metal-based alloy catalysts are extensively utilized in diverse applications. Nevertheless, finding a suitable preparation strategy to precisely moderate the catalytic active site remains a substantial challenge and subsequently improves the atomic utilization and reaction efficiency. Herein, the non-noble trimetallic alloy catalysts (Ni3Ga0.8In0.2/SiO2) were fabricated by using the strategy of incorporating doping (Indium as doping metal) and modulating the Ni3Ga bimetallic alloy in which to precisely tune the electronic structure of catalysts. The dispersion of alloy nanoparticles on the support was investigated by HRTEM, alongside the valence and elemental distribution of the components by EDS, XRD, and XPS, demonstrating the successful alloying of the composite. Moreover, other metal-doped Ni-Ga-M/SiO2 (M=Cu, Pt) catalysts and Ni-Ga alloy were prepared and evaluated catalytic performance by the model reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The experimental results revealed that suitable metal doping enhanced the reaction rate significantly, with the optimal effect of Indium among the different doping metals. Particular synergies arise from the homogeneous metals' similar atomic size and electronic structure. Theoretical calculations by Density Function Theory (DFT) have revealed that the doping of Indium resulted in electron transfer at the active interface of the catalyst, the gain of additional electrons by Ni, and the creation of electron vacancies at the active interface as a result of the electron deficiency of Ga and In, which enables the optimization of the catalytic reaction. In addition, the strategy can be extended to synthesize other trimetallic nanoparticle catalysts, which is expected to provide a new avenue for precise optimization and preparation of highly active non-precious metal catalysts.

Discontinuity in the Electronic Structure and Magnetic Order of β-Co1+xGa1-x.

The present work reports on the calculated electronic and magnetic structure of the binary Co-Ga system at high Co content. -CoGa adopts a simple cubic CsCl type structure. Well-ordered CoGa does not exhibit collective magnetism but is a paramagnetic, metallic compound. Neither Co nor Ga deficiency induces magnetic order; however, ferromagnetism is observed for Co-Ga anti-site disorder. The magnetic moment per cell increases by up to approximately 1.2 in the completely disordered body-centered cubic structure. With increasing Co content, CoGa maintains the CsCl type structure and becomes ferromagnetic. Most importantly, a discontinuity of the magnetic order with composition is observed at about 10% excess Co, where a change from a low magnetic moment state to a high moment state is observed. This is accompanied by a change in the electronic structure and transport properties. The discontinuity is forced by the increasing exchange splitting related to the localized moment of the additional Co atoms that replace Ga. Subsequently, the magnetic moment increases continuously up to 2.5 for . For , the structure changes to a face-centered cubic structure with random site occupation and the magnetic moment further increases. Above the magnetic discontinuity, the Curie temperature increases linearly with the Co content from the onset of ferromagnetism, until it reaches its maximum in pure Co.

High‐Performance Thermoelectric α‐Ag 9 Ga 1− x Te 6 Compounds with Ultralow Lattice Thermal Conductivity Originating from Ag 9 Te 2 Motifs

We have determined the complex atomic structure of high-temperature α-Ag9GaTe6 phase with a hexagonal lattice (P63mc space group, a=b=8.2766 Å, c=13.4349 Å). The structure has outer [GaTe4]5− tetrahedrons and inner [Ag9Te2]5+ clusters. All of the Ag ions are disorderly distributed in the lattice. Seven types of the Ag atoms constitute the cage-like [Ag9Te2]5+ clusters. The highly disordered Ag ions vibrate in-harmonically, producing strong coupling between low frequency optical phonons and acoustic phonons. This in conjunction with a low sound velocity of 1354 m s−1 leads to an ultralow thermal conductivity of 0.20 W m−1 K−1 at 673 K. Meanwhile, the deficiency of Ga in Ag9Ga1−xTe6 compounds effectively optimizes the electronic transport properties. Ag9Ga0.91Te6 attains a highest power factor of 0.40 mW m−1 K−2 at 673 K. All these contribute to a much-improved ZT value of 1.13 at 623 K for Ag9Ga0.95Te6, which is 41 % higher than that of the pristine Ag9GaTe6 sample.

High-Performance Thermoelectric α-Ag9 Ga1-x Te6 Compounds with Ultralow Lattice Thermal Conductivity Originating from Ag9 Te2 Motifs.

We have determined the complex atomic structure of high-temperature α-Ag9 GaTe6 phase with a hexagonal lattice (P63 mc space group, a=b=8.2766 Å, c=13.4349 Å). The structure has outer [GaTe4 ]5- tetrahedrons and inner [Ag9 Te2 ]5+ clusters. All of the Ag ions are disorderly distributed in the lattice. Seven types of the Ag atoms constitute the cage-like [Ag9 Te2 ]5+ clusters. The highly disordered Ag ions vibrate in-harmonically, producing strong coupling between low frequency optical phonons and acoustic phonons. This in conjunction with a low sound velocity of 1354 m s-1 leads to an ultralow thermal conductivity of 0.20 W m-1 K-1 at 673 K. Meanwhile, the deficiency of Ga in Ag9 Ga1-x Te6 compounds effectively optimizes the electronic transport properties. Ag9 Ga0.91 Te6 attains a highest power factor of 0.40 mW m-1 K-2 at 673 K. All these contribute to a much-improved ZT value of 1.13 at 623 K for Ag9 Ga0.95 Te6 , which is 41 % higher than that of the pristine Ag9 GaTe6 sample.

Multivariate Design and Analysis of Aircraft Heat Exchanger Under Multiple Working Conditions Within Flight Envelope

Abstract This paper presents a multi-condition design method for the aircraft heat exchanger (HEX), marking with lightweight, compactness, and wide range of working conditions. The quasi-traversal genetic algorithm (QT-GA) method is introduced to obtain the optimal values of five structural parameters including the height, the tube diameter, the tube pitch, and the tube rows. The QT-GA method solves the deficiency of the conventional GA in the convergence, and gives a clear correlation between design variables and outputs. Pressure drops, heat transfer, and the weight of the HEX are combined in a single objective function of GA in the HEX design, thus the optimal structure of the HEX suitable for all the working conditions can be directly obtained. After optimization, the weight of the HEX is reduced to 2.250 kg, more than 20% lower than a common weight of around 3 kg. Based on the optimal structure, the off-design performance of the HEX is further analyzed. Results show that the extreme working conditions for the heat transfer and the pressure drops are not consistent. It proves the advance of the multi-condition design method over the traditional single-condition design method. In general, the proposed QT-GA design method is an efficient way to solve the multi-condition problems related to the aircraft HEX or other energy systems.

MdKNOX15, a class I knotted-like transcription factor of apple, controls flowering and plant height by regulating GA levels through promoting the MdGA2ox7 transcription

Plant height and flowering characteristics are two main considerations for apple tree breeding. Hormone metabolism and signaling pathways are important for plant development. In this study, an apple KNOX transcription factor gene, MdKNOX15, was more highly expressed in the scion of the Fuji/M9 trees, which exhibit dwarfism and early flowering, than in the self-rooted Fuji trees. Subsequent analyses indicated that MdKNOX15 can bind directly to the MdGA2ox7 promoter to up-regulate transcription. The overexpression of MdKNOX15 in Arabidopsis resulted in dwarfism and delayed flowering due to GA deficiency. Furthermore, MdBLH, a cofactor of MdKNOX15, interacted with the HOX domain, which is a C-terminal sequence in MdKNOX15 with putative DNA-binding activity. The interaction between MdBLH and MdKNOX15 appears to prevent MdKNOX15 from binding to the MdGA2ox7 promoter and up-regulating expression. This study further elucidates the biological function of the apple KNOX15 transcription factor as well as the underlying mechanism involving plant growth and flower induction. The data presented herein may provide researchers with important information applicable for the molecular breeding of new apple varieties.

Tuning Ga Grading in Selenized Cu(In,Ga)Se2 Solar Cells by Formation of Ordered Vacancy Compound

Severe Ga accumulation at the back contact is regarded as one of the major limiting factors for high efficiency Cu(In,Ga)Se2 (CIGSe) solar cells fabricated by the sequential process. The Ga deficiency near the front surface of absorber leads to the reduction of open‐circuit voltage; however, controlling the Ga grading is quite challenging during the selenization process. Herein, the tuning of Ga profile is demonstrated by forming the ordered vacancy compound (OVC) phase at the beginning of selenization process under high Se partial pressure (PSe) with the precursor composed of a relatively high In content. The OVC phase formed with a columnar structure promotes Ga diffusion through Cu vacancies, resulting in Ga increase at the front side of CIGSe. However, high PSe also increases the thickness of MoSe2, significantly raising the series resistance. Thereby, a 5 nm TiN layer is deposited on top of Mo to suppress the formation of MoSe2. In addition, the extra Na‐contained precursor is added to increase the carrier concentration because the TiN layer also blocks the Na outdiffusion from the substrate. By controlling PSe, interlayer TiN thickness, and carrier concentration, a 16.04% record high efficiency of CIGSe solar cells (sulfur‐free) via elemental Se source is achieved.

Expression of Gibberellin Metabolism Genes and Signalling Components in Dwarf Phenotype of Breadfruit (Artocarpus altilis) Plants Growing on Marang (Artocarpus odoratissimus) Rootstocks.

Breadfruit (Artocarpus altilis) is a traditional staple tree crop throughout the tropics. The species is an evergreen tree 15–20 m; there are currently no size-controlling rootstocks within the species. Through interspecific grafting, a dwarf phenotype was identified in breadfruit plants growing on Marang (Artocarpus odoratissimus) rootstocks, which displayed ~60% reduction in plant height with ~80% shorter internodes. To gain insight into the molecular mechanism underlying rootstock-induced dwarfing, we investigated the involvement of gibberellin (GA) in reduction of stem elongation. Expression of GA metabolism genes was analysed in the period from 18 to 24 months after grafting. In comparison to self-graft and non-graft, scion stems on marang rootstocks displayed decrease in expression of a GA biosynthetic gene, AaGA20ox3, and increase in expression of a GA catabolic genes, AaGA2ox1, in the tested 6-month period. Increased accumulation of DELLA proteins (GA-signalling repressors) was found in scion stems growing on marang rootstocks, together with an increased expression of a DELLA gene, AaDELLA1. Exogenous GA treatment was able to restore the stem elongation rate and the internode length of scions growing on marang rootstocks. The possibility that GA deficiency forms a component of the mechanism underlying rootstock-induced breadfruit dwarfing is discussed.

Columnar growth phenotype in apple results from gibberellin deficiency by ectopic expression of a dioxygenase gene.

The apple cultivar McIntosh Wijcik, which is a mutant of 'McIntosh', exhibits a columnar growth phenotype (short internodes, few lateral branches, many spurs, etc.) that is controlled by a dominant Co gene. The candidate gene (MdDOX-Co), encoding a 2-oxoglutarate-dependent dioxygenase, is located adjacent to an insertion mutation. Non-columnar apples express MdDOX-Co in the roots, whereas columnar apples express MdDOX-Co in the aerial parts as well as in the roots. However, the function of MdDOX-Co remains unknown. Here, we characterized tobacco plants overexpressing MdDOX-Co. The tobacco plants showed the typical dwarf phenotype, which was restored by application of gibberellin A3 (GA3). Moreover, the dwarf tobacco plants had low concentrations of endogenous bioactive gibberellin A1 (GA1) and gibberellin A4 (GA4). Similarly, 'McIntosh Wijcik' contained low endogenous GA4 concentration and its dwarf traits (short main shoot and internodes) were partially reversed by GA3 application. These results indicate that MdDOX-Co is associated with bioactive GA deficiency. Interestingly, GA3 application to apple trees also resulted in an increased number of lateral branches and a decrease in flower bud number, indicating that gibberellin (GA) plays important roles in regulating apple tree architecture by affecting both lateral branch formation (vegetative growth) and flower bud formation (reproductive growth). We propose that a deficiency of bioactive GA by ectopic expression of MdDOX-Co in the aerial parts of columnar apples not only induces dwarf phenotypes but also inhibits lateral branch development and promotes flower bud formation, and assembly of these multiple phenotypes constructs the columnar tree form.

Expression of AtGA2ox1 enhances drought tolerance in maize

Drought is a major limiting factor to maize (Zea mays L.) yield. Plant hormones, including gibberellins (GAs), play important roles in plant response to drought stress. In previous studies, significant reductions in GAs levels have been reported under drought stress. In maize, GA content is correlated to drought tolerance, but the molecular mechanism remains unclear. In the present study, AtG2ox1, a member of the GA2ox family with a clear function, was used to create GA deficiency maize. The transgenic maize had a higher chlorophyll content and faster growth rate, when compared to the wild type (WT) plants, under drought stress in a greenhouse. The physiological and biochemical test results revealed that transgenic maize had decreased levels of GA1 and malondialdehyde (MDA), and increased content of proline and soluble sugars, and antioxidant enzyme activities, when compared to the WT. Furthermore, the transcriptomic analysis revealed that some differentially expressed genes involved in transcription factors correlated to drought stress and abiotic stress responses, and that signaling was enriched. All these results reveal the possible molecular mechanism of GA regulation in drought tolerance, in which the overexpression of AtGA2ox1 altered the expression of multiple genes correlated to the internal antioxidant system and maintenance of cell osmotic potential. The present study demonstrates that the overexpression of AtGA2ox1 could control GA content and improve drought tolerance in transgenic maize. Furthermore, this strategy represents a novel approach to address drought tolerance in maize breeding.

High Thermoelectric Performance in the Wide Band‐Gap AgGa1‐xTe2 Compounds: Directional Negative Thermal Expansion and Intrinsically Low Thermal Conductivity

AbstractA deficiency of Ga in wide band‐gap AgGa1‐xTe2 semiconductors (1.2 eV) can be used to optimize the electrical transport properties and reduce the thermal conductivity to achieve ZT > 1 at 873 K. First‐principles density functional theory calculations and a Boson peak observed in the low temperature heat capacity data indicate the presence of strong coupling between optical phonons with low frequency and heat carrying acoustical phonons, resulting in a depressed maximum of Debye frequency in the first Brillouin zone and low phonon velocities. Moreover, the AgTe bond lengths and TeAgTe bond angles increase with rising temperature, leading to a significant distortion of the [AgTe4]7− tetrahedra, but an almost unmodified [GaTe4]5− tetrahedra. This behavior results in lattice expansion in the ab‐plane and contraction along the c‐axis, corresponding to the positive and negative Gruneisen parameters in the phonon spectral calculations. This effect gives rise to the large anharmonic behavior of the lattice. These factors together with the low frequency vibrations of Ag and Te atoms in the structure lead to an ultralow thermal conductivity of 0.18 W m−1 K−1 at 873 K.

ITRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR–GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

Salinity Inhibits Rice Seed Germination by Reducing α-Amylase Activity via Decreased Bioactive Gibberellin Content.

Seed germination plays important roles in the establishment of seedlings and their subsequent growth; however, seed germination is inhibited by salinity, and the inhibitory mechanism remains elusive. Our results indicate that NaCl treatment inhibits rice seed germination by decreasing the contents of bioactive gibberellins (GAs), such as GA1 and GA4, and that this inhibition can be rescued by exogenous bioactive GA application. To explore the mechanism of bioactive GA deficiency, the effect of NaCl on GA metabolic gene expression was investigated, revealing that expression of both GA biosynthetic genes and GA-inactivated genes was up-regulated by NaCl treatment. These results suggest that NaCl-induced bioactive GA deficiency is caused by up-regulated expression of GA-inactivated genes, and the up-regulated expression of GA biosynthetic genes might be a consequence of negative feedback regulation of the bioactive GA deficiency. Moreover, we provide evidence that NaCl-induced bioactive GA deficiency inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression. Additionally, exogenous bioactive GA rescues NaCl-inhibited seed germination by enhancing α-amylase activity. Thus, NaCl treatment reduces bioactive GA content through promotion of bioactive GA inactivation, which in turn inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression.

Compositional accuracy of atom probe tomography measurements in GaN: Impact of experimental parameters and multiple evaporation events

A systematic study of the biases occurring in the measurement of the composition of GaN by Atom Probe Tomography was carried out, in which the role of surface electric field and laser pulse intensity has been investigated. Our data confirm that the electric field is the main factor influencing the measured composition, which exhibits a deficiency of N at low field and a deficiency of Ga at high field. The deficiency of Ga at high field is interpreted in terms of preferential evaporation of Ga. The detailed analysis of multiple evaporation events reveals that the measured composition is not affected by pile-up phenomena occurring in detection system. The analysis of correlation histograms yields the signature of the production of neutral N2 due to the dissociation of GaN32+ ions. However, the amount of N2 neutral molecules that can be detected cannot account for the N deficiency found at low field. Therefore, we propose that further mechanisms of neutral N evaporation could be represented by dissociation reactions such as GaN+→ Ga++ N and GaN2+→ Ga2++ N.

Sorghum DW1 positively regulates brassinosteroid signaling by inhibiting the nuclear localization of BRASSINOSTEROID INSENSITIVE 2

Semi-dwarf traits have been widely introgressed into cereal crops to improve lodging resistance. In sorghum (Sorghum bicolor L. Moench), four major unlinked dwarfing genes, Dw1-Dw4, have been introduced to reduce plant height, and among them, Dw3 and Dw1 have been cloned. Dw3 encodes a gene involved in auxin transport, whereas, Dw1 was recently isolated and identified as a gene encoding a protein of unknown function. In this study, we show that DW1 is a novel component of brassinosteroid (BR) signaling. Sorghum possessing the mutated allele of Dw1 (dw1), showed similar phenotypes to rice BR-deficient mutants, such as reduced lamina joint bending, attenuated skotomorphogenesis, and insensitivity against feedback regulation of BR-related genes. Furthermore, DW1 interacted with a negative regulator of BR signaling, BRASSINOSTEROID INSENSITIVE 2 (BIN2), and inhibited its nuclear localization, indicating that DW1 positively regulates BR signaling by inhibiting the function of BIN2. In contrast to rice and wheat breeding which used gibberellin (GA) deficiency to reduce plant height, sorghum breeding modified auxin and BR signaling. This difference may result from GA deficiency in rice and wheat does not cause deleterious side effects on plant morphology, whereas in sorghum it leads to abnormal culm bending.

Arabidopsis NAC Transcription Factor JUNGBRUNNEN1 Exerts Conserved Control Over Gibberellin and Brassinosteroid Metabolism and Signaling Genes in Tomato.

The Arabidopsis thaliana NAC transcription factor JUNGBRUNNEN1 (AtJUB1) regulates growth by directly repressing GA3ox1 and DWF4, two key genes involved in gibberellin (GA) and brassinosteroid (BR) biosynthesis, respectively, leading to GA and BR deficiency phenotypes. AtJUB1 also reduces the expression of PIF4, a bHLH transcription factor that positively controls cell elongation, while it stimulates the expression of DELLA genes, which are important repressors of growth. Here, we extend our previous findings by demonstrating that AtJUB1 induces similar GA and BR deficiency phenotypes and changes in gene expression when overexpressed in tomato (Solanum lycopersicum). Importantly, and in accordance with the growth phenotypes observed, AtJUB1 inhibits the expression of growth-supporting genes, namely the tomato orthologs of GA3ox1, DWF4 and PIF4, but activates the expression of DELLA orthologs, by directly binding to their promoters. Overexpression of AtJUB1 in tomato delays fruit ripening, which is accompanied by reduced expression of several ripening-related genes, and leads to an increase in the levels of various amino acids (mostly proline, β-alanine, and phenylalanine), γ-aminobutyric acid (GABA), and major organic acids including glutamic acid and aspartic acid. The fact that AtJUB1 exerts an inhibitory effect on the GA/BR biosynthesis and PIF4 genes but acts as a direct activator of DELLA genes in both, Arabidopsis and tomato, strongly supports the model that the molecular constituents of the JUNGBRUNNEN1 growth control module are considerably conserved across species.

SHOEBOX Modulates Root Meristem Size in Rice through Dose-Dependent Effects of Gibberellins on Cell Elongation and Proliferation.

Little is known about how the size of meristem cells is regulated and whether it participates in the control of meristem size in plants. Here, we report our findings on shoebox (shb), a mild gibberellin (GA) deficient rice mutant that has a short root meristem size. Quantitative analysis of cortical cell length and number indicates that shb has shorter, rather than fewer, cells in the root meristem until around the fifth day after sowing, from which the number of cortical cells is also reduced. These defects can be either corrected by exogenous application of bioactive GA or induced in wild-type roots by a dose-dependent inhibitory effect of paclobutrazol on GA biosynthesis, suggesting that GA deficiency is the primary cause of shb mutant phenotypes. SHB encodes an AP2/ERF transcription factor that directly activates transcription of the GA biosynthesis gene KS1. Thus, root meristem size in rice is modulated by SHB-mediated GA biosynthesis that regulates the elongation and proliferation of meristem cells in a developmental stage-specific manner.

The effects of pulse repetition rate on the structural, optical, and electrical properties of CIGS films grown by pulsed laser deposition

Well crystallized CuIn1−xGaxSe2 (CIGS, x=0.22–0.26) films were deposited at the temperatures below 300°C by pulsed laser deposition. Increasing pulse repetition rate from 5Hz to 1kHz significantly increased the crystallinity of films. All the films were Cu rich and those deposited with 5Hz showed higher Ga deficiency, but in those deposited with 1kHz the loss of Se was higher. The growth mechanisms under the low and high repetition rates as well as their effects on the grain size and composition were discussed in detail. All the films had p-type conductivity. The resistivity of 1kHz films was two times higher but the carrier concentration was four times lower than the 5Hz films. I–V characteristics were measured on the n-ZnO/p-CIGS heterojunctions. The junction made with 1kHz film had a single ideality factor of 1.3 up to the high current limit, which is often seen in the high efficiency CIGS solar cells, whereas the I–V curve of the junction made with 5Hz film consisted of two sections described by large ideality factors of 3.0 and 4.8, respectively, indicating that there are two recombination mechanisms each of which dominates at a different current region.

Transcripts of two ent-copalyl diphosphate synthase genes differentially localize in rice plants according to their distinct biological roles.

Gibberellins (GAs) are diterpenoid phytohormones that regulate various aspects of plant growth. Tetracyclic hydrocarbon ent-kaurene is a biosynthetic intermediate of GAs, and is converted from geranylgeranyl diphosphate, a common precursor of diterpenoids, via ent-copalyl diphosphate (ent-CDP) through successive cyclization reactions catalysed by two distinct diterpene synthases, ent-CDP synthase and ent-kaurene synthase. Rice (Oryza sativa L.) has two ent-CDP synthase genes, OsCPS1 and OsCPS2. It has been thought that OsCPS1 participates in GA biosynthesis, while OsCPS2 participates in the biosynthesis of phytoalexins, phytocassanes A-E, and oryzalexins A-F. It has been shown previously that loss-of-function OsCPS1 mutants display a severe dwarf phenotype caused by GA deficiency despite possessing another ent-CDP synthase gene, OsCPS2. Here, experiments were performed to account for the non-redundant biological function of OsCPS1 and OsCPS2. Quantitative reverse transcription-PCR (qRT-PCR) analysis showed that OsCPS2 transcript levels were drastically lower than those of OsCPS1 in the basal parts, including the meristem of the second-leaf sheaths of rice seedlings. qRT-PCR results using tissue samples prepared by laser microdissection suggested that OsCPS1 transcripts mainly localized in vascular bundle tissues, similar to Arabidopsis CPS, which is responsible for GA biosynthesis, whereas OsCPS2 transcripts mainly localized in epidermal cells that address environmental stressors such as pathogen attack. Furthermore, the OsCPS2 transgene under regulation of the OsCPS1 promoter complemented the dwarf phenotype of an OsCPS1 mutant, oscps1-1. The results indicate that transcripts of the two ent-CDP synthase genes differentially localize in rice plants according to their distinct biological roles, OsCPS1 for growth and OsCPS2 for defence.

Gibberellin deficiency pleiotropically induces culm bending in sorghum: an insight into sorghum semi-dwarf breeding.

Regulation of symmetrical cell growth in the culm is important for proper culm development. So far, the involvement of gibberellin (GA) in this process has not yet been demonstrated in sorghum. Here, we show that GA deficiency resulting from any loss-of-function mutation in four genes (SbCPS1, SbKS1, SbKO1, SbKAO1) involved in the early steps of GA biosynthesis, not only results in severe dwarfism but also in abnormal culm bending. Histological analysis of the bent culm revealed that the intrinsic bending was due to an uneven cell proliferation between the lower and upper sides of culm internodes. GA treatment alleviated the bending and dwarfism in mutants, whereas the GA biosynthesis inhibitor, uniconazole, induced such phenotypes in wild-type plants— both in a concentration-dependent manner, indicating an important role of GA in controlling erectness of the sorghum culm. Finally, we propose that because of the tight relationship between GA deficiency-induced dwarfism and culm bending in sorghum, GA-related mutations have unlikely been selected in the history of sorghum breeding, as could be inferred from previous QTL and association studies on sorghum plant height that did not pinpoint GA-related genes.