Rice myo-inositol-3-phosphate synthase 2 (RINO2) alleviates heat injury-induced impairment in pollen germination and tube growth by modulating Ca2+ signaling and actin filament cytoskeleton.

Low phytic acid (lpa) crop is considered as an effective strategy to improve crop nutritional quality, but a substantial decrease in phytic acid (PA) usually has negative effect on agronomic performance and its response to environment adversities. Myo-inositol-3-phosphate synthase (MIPS) is the rate-limiting enzyme in PA biosynthesis pathway, and regarded as the prime target for engineering lpa crop. In this paper, the rice MIPS gene (RINO2) knockout mutants and its wild type were performed to investigate the genotype-dependent alteration in the heat injury-induced spikelet fertility and its underlying mechanism for rice plants being imposed to heat stress at anthesis. Results indicated that RINO2 knockout significantly enhanced the susceptibility of rice spikelet fertility to heat injury, due to the severely exacerbated obstacles in pollen germination and pollen tube growth in pistil for RINO2 knockout under high temperature (HT) at anthesis. The loss of RINO2 function caused a marked reduction in inositol and phosphatidylinositol derivative concentrations in the HT-stressed pollen grains, which resulted in the strikingly lower content of phosphatidylinositol 4,5-diphosphate (PI (4,5) P2) in germinating pollen grain and pollen tube. The insufficient supply of PI (4,5) P2 in the HT-stressed pollen grains disrupted normal Ca2+ gradient in the apical region of pollen tubes and actin filament cytoskeleton in growing pollen tubes. The severely repressed biosynthesis of PI (4,5) P2 was among the regulatory switch steps leading to the impaired pollen germination and deformed pollen tube growth for the HT-stressed pollens of RINO2 knockout mutants.

Rice ins(3)P synthase1 (RINO1) participates in embryonic development by regulating inositol-associated changes in auxin synthesis and its distribution.

The breeding of low phytic acid (LPA) crops is widely considered an effective strategy to improve crop nutrition, but the LPA crops usually have inferior seed germination performance. To clarify the reason for the suboptimal seed performance of LPA rice, this study investigated the impact of reduced seed phytic acid (InsP6) content in rice ins(3)P synthase1 (EC 5.5.1.4, RINO1), one of the key targets for engineering LPA rice, knockouton cellular differentiation in seed embryos and its relation to myo-inositol metabolism and auxin signalling during embryogenesis. The results indicated that the homozygotes of RINO1 knockout could initiate differentiation at the early stage of embryogenesis but failed to form normal differentiation of plumule and radicle primordia. The loss of RINO1 function disrupted vesicle trafficking and auxin signalling due to the significantly lowered phosphatidylinositides (PIs) concentration in seed embryos, thereby leading to the defects of seed embryos without the recognizable differentiation of shoot apex meristem (SAM) and radicle apex meristem (RAM) for the homozygotes of RINO1 knockout. The abnormal embryo phenotype of RINO1 homozygotes was partially rescued by exogenous spraying of inositol and indole-3-acetic acid (IAA) in rice panicle. Thus, RINO1 is crucial for both seed InsP6 biosynthesis and embryonic development. The lower phosphatidylinositol (4,5)-bisphosphate (PI (4,5) P2) concentration and the disorder auxin distribution induced by insufficient inositol supply in seed embryos were among the regulatory switch steps leading to aberrant embryogenesis and failure of seed germination in RINO1 knockout.

ABA-triggered ROS burst in rice developing anthers is critical for tapetal programmed cell death induction and heat stress-induced pollen abortion.

High temperatures (HT) cause pollen abortion and poor floret fertility in rice, which is closely associated with excessive accumulation of reactive oxygen species (ROS) in the developing anthers. However, the relationships between accumulation of abscisic acid (ABA) and ROS, and their effects on tapetum-specific programmed cell death (PCD) in HT-stressed anthers are poorly characterised. Here, we determined the spatiotemporal changes in ABA and ROS levels, and their relationships with tapetal PCD under HT exposure. Mutants lacking ABA-activated protein kinase 2 (SAPK2) functions and exogenous ABA treatments were used to explore the effects of ABA signalling on the induction of PCD and ROS accumulation during pollen development. HT-induced pollen abortion was tightly associated with ABA accumulation and oxidative stress. The higher ABA level in HT-stressed anthers resulted in the earlier initiation of PCD induction and subsequently abnormal tapetum degeneration by activating ROS accumulation in developing anthers. Interactions between SAPK2 and DEAD-box ATP-dependent RNA helicase elF4A-1 (RH4) were required for ABA-induced ROS generation in developing anthers. The OsSAPK2 knockout mutants showed the impaired PCD responses in the absence of HT. However, the deficiency of SAPK2 functions did not suppress the ABA-mediated ROS generation in HT-stressed anthers.

Disruption of a Upf1-like helicase-encoding gene OsPLS2 triggers light-dependent premature leaf senescence in rice.

KEY MESSAGE: The OsPLS2 locus was isolated and cloned by map-based cloning that encodes a Upf1-like helicase. Disruption of OsPLS2 accelerated light-dependent leaf senescence in the rice mutant of ospls2. Leaf senescence is a very complex physiological process controlled by both genetic and environmental factors, however its underlying molecular mechanisms remain elusive. In this study, we report a novel Oryza sativa premature leaf senescence mutant (ospls2). Through map-based cloning, a G-to-A substitution was determined at the 1st nucleotide of the 13th intron in the OsPLS2 gene that encodes a Upf1-like helicase. This mutation prompts aberrant splicing of OsPLS2 messenger and consequent disruption of its full-length protein translation, suggesting a negative role of OsPLS2 in regulating leaf senescence. Wild-type rice accordingly displayed a progressive drop of OsPSL2 protein levels with age-dependent leaf senescence. Shading and light filtration studies showed that the ospls2 phenotype, which was characteristic of photo-oxidative stress and reactive oxygen species (ROS) accumulation, was an effect of irritation by light. When continuously exposed to far-red light, exogenous H2O2 and/or abscisic acid (ABA), the ospls2 mutant sustained hypersensitive leaf senescence. In consistence, light and ROS signal pathways in ospls2 were activated by down-regulation of phytochrome genes, and up-regulation of PHYTOCHROME-INTERACTING FACTORS (PIFs) and WRKY genes, all promoting leaf senescence. Together, these data indicated that OsPLS2 played an essential role in leaf senescence and its disruption triggered light-dependent leaf senescence in rice.

Abiotic Stresses Intervene with ABA Signaling to Induce Destructive Metabolic Pathways Leading to Death: Premature Leaf Senescence in Plants.

Abiotic stresses trigger premature leaf senescence by affecting some endogenous factors, which is an important limitation for plant growth and grain yield. Among these endogenous factors that regulate leaf senescence, abscisic acid (ABA) works as a link between the oxidase damage of cellular structure and signal molecules responding to abiotic stress during leaf senescence. Considering the importance of ABA, we collect the latest findings related to ABA biosynthesis, ABA signaling, and its inhibitory effect on chloroplast structure destruction, chlorophyll (Chl) degradation, and photosynthesis reduction. Post-translational changes in leaf senescence end with the exhaustion of nutrients, yellowing of leaves, and death of senescent tissues. In this article, we review the literature on the ABA-inducing leaf senescence mechanism in rice and Arabidopsis starting from ABA synthesis, transport, signaling receptors, and catabolism. We also predict the future outcomes of investigations related to other plants. Before changes in translation occur, ABA signaling that mediates the expression of NYC, bZIP, and WRKY transcription factors (TFs) has been investigated to explain the inducing effect on senescence-associated genes. Various factors related to calcium signaling, reactive oxygen species (ROS) production, and protein degradation are elaborated, and research gaps and potential prospects are presented. Examples of gene mutation conferring the delay or induction of leaf senescence are also described, and they may be helpful in understanding the inhibitory effect of abiotic stresses and effective measures to tolerate, minimize, or resist their inducing effect on leaf senescence.

A 22-bp deletion in OsPLS3 gene encoding a DUF266-containing protein is implicated in rice leaf senescence.

Key message The OsPLS3 locus was isolated by map-based cloning that encodes a DUF266-containing protein. OsPLS3 regulates the onset of leaf senescence in rice. Glycosyltransferases (GTs) are one of the most important enzyme groups required for the modification of plant secondary metabolites and play a crucial role in plant growth and development, however the biological functions of most GTs remain elusive. We reported here the identification and characterization of a novel Oryza sativa premature leaf senescence mutant (ospls3). Through map-based cloning strategy, we determined that 22-bp deletion in the OsPLS3 gene encoding a domain of unknown function 266 (DUF266)-containing protein, a member of GT14-like, underlies the premature leaf senescence phenotype in the ospls3 mutant. The OsPLS3 mRNA levels progressively declined with the age-dependent leaf senescence in wild-type rice, implying a negative role of OsPLS3 in regulating leaf senescence. Physiological analysis, and histochemical staining and transmission electron microscopy assays indicated that the ospls3 mutant accumulated higher levels of ethylene and reactive oxygen species than its wild type. Furthermore, the ospls3 mutant showed hypersensitivity to exogenous 1-aminocyclopropane-1-carboxylic acid, H2O2 and high level of cytokinins. Our results indicated that the DUF266-containing gene OsPLS3 plays an important role in the onset of leaf senescence, in part through cytokinin and ethylene signaling in rice.

Involvement of CAT in the detoxification of HT-induced ROS burst in rice anther and its relation to pollen fertility.

KEY MESSAGE: HT-induced ROS burst in developing anther is closely related to the lowered CAT activity as the result of the markedly suppressed OsCATB transcript, thereby causing severe fertility injury for rice plants exposed to HT at meiosis stage. The reproductive stage of rice plants is highly sensitive to heat stress. In this paper, different rice cultivars were used to investigate the relationship of HT-induced floret sterility with reactive oxygen species (ROS) detoxification in rice anthers under well-controlled climatic conditions. Results showed that high temperature (HT) exposure significantly enhanced the ROS level and malondialdehyde (MDA) content in developing anther, and the increase in ROS amount in rice anther under HT exposure was closely associated with HT-induced decline in the activities of several antioxidant enzymes. For various antioxidant enzymes, SOD and CAT were more susceptible to the ROS burst in rice anther induced by HT exposure than APX and POD, in which SOD and CAT activity in developing anther decreased significantly by HT exposure, whereas APX activity was relatively stable among different temperature regimes. HT-induced decrease in CAT activity was attributable to the suppressed transcript of OsCATB. This occurrence was strongly responsible for HT-induced increase in ROS level and oxidative-damage in rice anther, thereby it finally caused significant reduction in pollen viability and floret fertility for the rice plants exposed to HT during meiosis. Exogenous application of 1000 µM salicylic acid (SA) may alleviate HT-induced reduction in pollen viability and floret fertility, concomitantly with the increased CAT activity and reduced ROS level in rice anther.

[Research on ground reaction forces and utilized coefficient of friction of turning gait].

Utilized coefficient of friction(UCOF), which is calculated with ground reaction forces(GRF), is an effective factor to predict the possibility of slip. For researching the UCOF values of different turning strategies and then predicting the possibility of slip, this study selected 10 healthy young men to perform straight walking and 60° and 90°turning using two turning strategies(step turning and spin turning). ATMI force plate was used to collect the data of GRF,and then the UCOF values of different walking conditions were calculated. The study showed that difference of the medial-lateral force in different walking conditions was great; the slip possibility of turning was significantly greater than that of straight walking. For spin turn, turning angle had no significant effect on peak UCOF values. For step turn, the propulsive force decreased with the increase of turning angle, which caused a result that the peak UCOF values of 60° turn were significantly greater than that for 90° turn. This suggests that turning angle had little effect on possibility of slip of spin turning but great effect on that of step turning, and the greater angle led smaller possibility of slip.

A single cytosine deletion in the OsPLS1 gene encoding vacuolar-type H+-ATPase subunit A1 leads to premature leaf senescence and seed dormancy in rice.

Leaf senescence is a programmed developmental process orchestrated by many factors, but its molecular regulation is not yet fully understood. In this study, a novel Oryza sativa premature leaf senescence mutant (ospls1) was examined. Despite normal development in early seedlings, the ospls1 mutant leaves displayed lesion-mimics and early senescence, and a high transpiration rate after tillering. The mutant also showed seed dormancy attributable to physical (defect of micropyle structure) and physiological (abscisic acid sensitivity) factors. Using a map-based cloning approach, we determined that a cytosine deletion in the OsPLS1 gene encoding vacuolar H(+)-ATPase subunit A1 (VHA-A1) underlies the phenotypic abnormalities in the ospls1 mutant. The OsPSL1/VHA-A1 transcript levels progressively declined with the age-dependent leaf senescence in both the ospls1 mutant and its wild type. The significant decrease in both OsPSL1/VHA-A1 gene expression and VHA enzyme activity in the ospls1 mutant strongly suggests a negative regulatory role for the normal OsPLS1/VHA-A1 gene in the onset of rice leaf senescence. The ospls1 mutant featured higher salicylic acid (SA) levels and reactive oxygen species (ROS) accumulation, and activation of signal transduction by up-regulation of WRKY genes in leaves. Consistent with this, the ospls1 mutant exhibited hypersensitivity to exogenous SA and/or H2O2 Collectively, these results indicated that the OsPSL1/VAH-A1 mutation played a causal role in premature leaf senescence through a combination of ROS and SA signals. To conclude, OsPLS1 is implicated in leaf senescence and seed dormancy in rice.

[Comparison of Characteristics between Different Turning Strategies].

Turning gait is very common in daily lives.However,study of turning is still limited.For researching the differences of the walking characteristics between straight gait and turning gait and between different turning strategies,and for analyzing the endopathic factor,this study selected 10 healthy young men to perform straight walking and 90°turning using two turning strategies(outside leg turning and inside leg turning).The Vicon capture system and plantar pressure capture system were used to measure gait parameters and plantar pressure parameters at the same time.The study showed that stride velocity reduced while stride time and proportion of stance time increased when turning was compared to straight walking.Inside leg turning strategy needed stronger muscle controlling and could promote turning,while outside leg turning strategy was more stable.This results will offer data for projecting gait of biped robot and provide reference value for walking rehabilitation training design and development of walking assistive equipments,etc.

How abiotic stresses trigger sugar signaling to modulate leaf senescence?

Plants have evolved the adaptive capacity to mitigate the negative effect of external adversities at chemical, molecular, cellular, and physiological levels. This capacity is conferred by triggering the coordinated action of internal regulatory factors, in which sugars play an essential role in the regulating chloroplast degradation and leaf senescence under various stresses. In this review, we summarize the recent findings on the senescent-associated changes in carbohydrate metabolism and its relation to chlorophyl degradation, oxidative damage, photosynthesis inhibition, programmed cell death (PCD), and sink-source relation as affected by abiotic stresses. The action of sugar signaling in regulating the initiation and progression of leaf senescence under abiotic stresses involves interactions with various plant hormones, reactive oxygen species (ROS) burst, and protein kinases. This discussion aims to elucidate the complex regulatory network and molecular mechanisms that underline sugar-induced leaf senescence in response to various abiotic stresses. The imperative role of sugar signaling in regulating plant stress responses potentially enables the production of crop plants with modified sugar metabolism. This, in turn, may facilitate the engineering of plants with improved stress responses, optimal life span and higher yield achievement.

Disruptions of sugar utilization and carbohydrate metabolism in rice developing anthers aggravated heat stress-induced pollen abortion.

High temperature (HT) stress at reproductive stage is one of most important environment negatively affecting spikelet fertility and rice yield. In this study, the effect of HT exposure on the sugar composition and carbohydrate metabolism in developing anthers and its relation to floret fertility and pollen viability were investigated by different temperature regimes under well-controlled climatic condition. Result showed that HT exposure during microspore development significantly reduced the starch deposition in developing anther and evidently disrupted the spatial distribution of sugar and starch concentrations in different compartments of rice anther, with the higher ratio of sucrose to hexose concentrations in HT-stressed anthers relative to the control ones. Under HT exposure, the amount of starch deposition in the fraction of sporophytic tissues dropped evidently, while the concentrations of sucrose and starch in anther wall tissue enhanced significantly, suggesting that HT exposure impaired the translocation of sucrose from the anther wall tissue to the sporophytic tissues inside rice anther. Furthermore, we presented possible contribution of various genes and key enzymes involving in sugar conversion and carbohydrate metabolism in developing anther to the formation of HT-induced pollen abortion by disrupting the sugar utilization in HT-stressed anther. HT exposure suppressed the activities of cell wall and vacuolar invertase, hexokinase, and ADP-glucose pyrophosphorylase in developing anther, while it was opposite for the effect of HT exposure on sucrose synthase and fructokinase. HT-induced suppression of OsCWIN3 in the anther walls might be strongly responsible for the HT-induced impairments of sugar utilization in HT-stressed anthers.

Involvement of plant signaling network and cell metabolic homeostasis in nitrogen deficiency-induced early leaf senescence.

Nitrogen (N) is a basic building block that plays an essential role in the maintenance of normal plant growth and its metabolic functions through complex regulatory networks. Such the N metabolic network comprises a series of transcription factors (TFs), with the coordinated actions of phytohormone and sugar signaling to sustain cell homeostasis. The fluctuating N concentration in plant tissues alters the sensitivity of several signaling pathways to stressful environments and regulates the senescent-associated changes in cellular structure and metabolic process. Here, we review recent advances in the interaction between N assimilation and carbon metabolism in response to N deficiency and its regulation to the nutrient remobilization from source to sink during leaf senescence. The regulatory networks of N and sugar signaling for N deficiency-induced leaf senescence is further discussed to explain the effects of N deficiency on chloroplast disassembly, reactive oxygen species (ROS) burst, asparagine metabolism, sugar transport, autophagy process, Ca2+ signaling, circadian clock response, brassinazole-resistant 1 (BZRI), and other stress cell signaling. A comprehensive understanding for the metabolic mechanism and regulatory network underlying N deficiency-induced leaf senescence may provide a theoretical guide to optimize the source-sink relationship during grain filling for the achievement of high yield by a selection of crop cultivars with the properly prolonged lifespan of functional leaves and/or by appropriate agronomic managements.

Ethanol suppresses rice seed germination through inhibiting ROS signaling.

Ethanol is frequently used not only as priming but also as a solvent to dissolve hardly water-soluble phytohormones gibberellic acid (GA3) and abscisic acid (ABA) in seed germination. However, the molecular and physiological mechanisms of ethanol's impact on seed germination remain elusive. In this report, we investigated how ethanol affected reactive oxygen species (ROS) during rice seed germination. Ethanol at a concentration of 3.5% (v/v) inhibited 90% seed germination, which was almost reversed by H2O2. H2O2 contents in embryos were reduced by ethanol after 18 h imbibition. Antioxidant enzymes assays revealed that only superoxide dismutase (SOD) activities in seed embryos were lowered by ethanol, in line with the suppressed mRNA expression of SOD genes during imbibition. Additionally, compared to the mock condition, ethanol increased ABA contents but decreased GA (GA1 and GA3) in seed embryos, resulting in disharmonizing GA/ABA balance. Conceivably ethanol induced transcription of OsNCEDs, the key genes for ABA biosynthesis, and OsABA8ox3, a key gene for ABA catabolism. Furthermore, ethanol promoted ABA signaling by upregulating ABA receptor genes and ABA-responsive element (ABRE)-binding protein/ABRE-binding factors during imbibition. Overall, our results demonstrate that lowering of H2O2 levels due to suppressed SOD activities in rice germinating seed embryos is the decisive factor for ethanol-induced inhibition of seed germination, and GA/ABA balance and ABA signaling also play important roles in ethanol's inhibitory impact on seed germination.

Assessing the Influencing Factors of Electronic Word-of-Mouth on CSR Issues. A Case of Hospotality Service Industry of China.

Corporate social responsibility (CSR) information can be effectively disseminated via social media in a variety of industries, including the hospitality sector. In the same way, the media has a significant impact on CSR because the news media helps companies achieve their CSR goals. Prior research has not examined the main factors that influence electronic word of mouth (eWOM) on media coverage of CSR issues via social networking websites. For the purpose of examining the most significant predictors of intention to share or comment on negative CSR news reported by one media outlet on a specific social networking site (SNS). 677 Wechat users in China were surveyed in order to test the proposed model empirically. According to the findings of the study, eWOM intentions are positively influenced by environmental CSR content, and advertisement related CSR content. It also confirmed that the value of information is positively influenced by the credibility of the source. The variables interpersonal influencer impact and privacy concerns had no significant relationship, nor did they have any significant relationship with the intentions to share and comment on Wechat. Further the study findings suggest the theoretical and managerial policy recommendation for decision makers.

Combined Effect of Nitrogen Fertilizer Application and High Temperature on Grain Quality Properties of Cooked Rice.

Ambient temperature and nitrogen (N) fertilizer are two of the most important factors that affect rice grain quality. However, less information has been available on the interactive effect of N fertilizer and ambient temperature on grain quality under stressful high temperature (HT). In this article, the effects of panicle N fertilizer, ambient temperature, and their interaction on starch composition, particle size distribution of starch granules, starch physicochemical properties, and storage protein accumulation in milled grains were investigated to clarify the potential role of panicle N fertilizer topdressing in regulating rice grain quality under stressful HT by using a two-factor experiment of three N levels in combination with two temperature regimes. Results showed that appropriate application of panicle N fertilizer could attenuate the adverse effect of HT during grain filling on milling quality and chalky occurrence to some extent, particularly for the effective alleviation of HT-induced decrease in milling quality. However, the topdressing of panicle N fertilizer tended to enhance starch gelatinization enthalpy (ΔH) and its setback viscosity in HT-ripening grains, with the simultaneous decrements in the number and surface area proportions of smaller starch granules under the higher N fertilizer in combination with HT exposure. The effects of higher nitrogen fertilizer and HT exposure on total protein content and gluten composition of grains were additively increased. Hence, the topdressing of panicle N fertilizer exacerbated HT-induced deterioration in cooking and eating quality, rather than alleviating the negative impact of HT exposure on the palatability of cooked rice.

ALK, the key gene for gelatinization temperature, is a modifier gene for gel consistency in rice.

Gelatinization temperature (GT) is an important parameter in evaluating the cooking and eating quality of rice. Indeed, the phenotype, biochemistry and inheritance of GT have been widely studied in recent times. Previous map-based cloning revealed that GT was controlled by ALK gene, which encodes a putative soluble starch synthase II-3. Complementation vector and RNAi vector were constructed and transformed into Nipponbare mediated by Agrobacterium. Phenotypic and molecular analyses of transgenic lines provided direct evidence for ALK as a key gene for GT. Meanwhile, amylose content, gel consistency and pasting properties were also affected in transgenic lines. Two of four nonsynonymous single nucleotide polymorphisms in coding sequence of ALK were identified as essential for GT. Based on the single nucleotide polymorphisms (SNPs), two new sets of SNP markers combined with one cleaved amplified polymorphic sequence marker were developed for application in rice quality breeding.

A Consensus-Reaching Approach to the Evaluation of Product Design Alternatives with Multiple Preference Structures.

With interdisciplinarity being an important characteristic of contemporary product design, the evaluation of design alternatives also involves multiple disciplines, and the evaluator group usually consists of evaluators from different fields and with obvious heterogeneous characteristics. To effectively satisfy the heterogeneous needs of evaluators and improve the credibility of evaluation results, the paper introduces a consensus-reaching approach that incorporates multiple preferences to the evaluation of product design alternatives. First, in order to obtain individual preference information, each evaluator is asked to evaluate all the design alternatives using a preference structure that he/she is familiar with. Second, we use a transfer function to uniform the evaluation information obtained from various preference structures into a complementary judgment matrix. Then, we use the Hybrid Weighted Averaging (HWA) operator weight determination model to aggregate the preference information and obtain the group preference information. Then, we measure the consensus degree between individual evaluators and the group using a consensus measurement method. After that, we use the feedback mechanism to instruct individual evaluators to modify their preferences until a consensus is achieved. We explain the application steps and the feasibility of this approach through the evaluation of the design alternatives of multichannel fluorescence immunochromatography analyzers (MFIAs).

SSIIIa-RNAi suppression associated changes in rice grain quality and starch biosynthesis metabolism in response to high temperature.

High temperature (HT) is a main environmental restraint that affects rice yield and grain quality. In this study, SSIIIa-RNAi and its wild-type (WT) were used to investigate the effect of HT exposure on the isozyme-specific variation of several key starch biosynthesis enzymes in developing endosperms and its relation to starch properties. SSIIIa-RNAi had minimal impact on grain chalky occurrence under normal temperature growth, but it could up-grade the susceptibility of grain chalky occurrence to HT exposure, due to the relatively sensitive response of AGPase and SSI to HT exposure. Different from WT, SSIIIa-RNAi had the relatively enriched proportion of chains with DP 13-16 under HT, and HT-induced decline in the proportion of DP < 12 became much larger for SSIIIa-RNAi relative to WT. SSIIIa-RNAi significantly enhanced the expression of SSI isozyme and total SS activity, whereas SSI-RNAi deficiency had little impact on the expression of SSIIIa isozyme. In this regard, the compensatory increase in SSI isozyme as a result of SSIIIa deficiency occurred only in a one-way manner. SSIIIa-RNAi caused a striking elevation in BEIIa expression, and the effect of SSIIIa deficiency on the chain length distribution in relation to HT exposure was closely associated with the participation of BEIIa, SSI, and their interaction in amylopectin biosynthesis.

Drought-stimulated activity of plasma membrane nicotinamide adenine dinucleotide phosphate oxidase and its catalytic properties in rice.

The activity of plasma membrane (PM) nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and its catalytic properties in rice was investigated under drought stress conditions. Drought stress led to decreased leaf relative water content (RWC) and, as a result of drought-induced oxidative stress, the activities of antioxidant enzymes increased significantly. More interestingly, the intensity of applied water stress was correlated with increased production of H2O2 and O2 (-) and elevated activity of PM NADPH oxidase, a key enzyme of reactive oxygen species generation in plants. Histochemical analyses also revealed increased H2O2 and O2 (-) production in drought-stressed leaves. Application of diphenylene iodonium (DPI), an inhibitor of PM NADPH oxidase, did not alleviate drought-induced production of H2O2 and O2 (-). Catalysis experiments indicated that the rice PM NADPH oxidase was partially flavin-dependent. The pH and temperature optima for this enzyme were 9.8 and 40 degrees C, respectively. In addition, drought stress enhanced the activity under alkaline pH and high temperature conditions. These results suggest that a complex regulatory mechanism, associated with the NADPH oxidase-H2O2 system, is involved in the response of rice to drought stress.