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The percentage of amylose in the endosperm of rice (Oryza sativa) largely determines grain cooking and eating qualities. Granule‐bound starch synthase I (GBSSI) and GBSSII are responsible for amylose biosynthesis in the endosperm and leaf, respectively. Here, we identified OsGBP, a rice GBSS‐binding protein that interacted with GBSSI and GBSSII in vitro and in vivo. The total starch and amylose contents in osgbp mutants were significantly lower than those of wild type in leaves and grains, resulting in reduced grain weight and quality. The carbohydrate‐binding module 48 (CBM48) domain present in the C‐terminus of OsGBP is crucial for OsGBP binding to starch. In the osgbp mutant, the extent of GBSSI and GBSSII binding to starch in the leaf and endosperm was significantly lower than wild type. Our data suggest that OsGBP plays an important role in leaf and endosperm starch biosynthesis by mediating the binding of GBSS proteins to developing starch granules. This elucidation of the function of OsGBP enhances our understanding of the molecular basis of starch biosynthesis in rice and contributes information that can be potentially used for the genetic improvement of yield and grain quality. [ABSTRACT FROM AUTHOR]

Summary: Starch is the main form of energy storage in higher plants. Although several enzymes and regulators of starch biosynthesis have been defined, the complete molecular machinery remains largely unknown. Screening for irregularities in endosperm formation in rice represents valuable prospect for studying starch synthesis pathway. Here, we identified a novel rice white‐core endosperm and defective grain filling mutant, ospk2, which displays significantly lower grain weight, decreased starch content and alteration of starch physicochemical properties when compared to wild‐type grains. The normal starch compound granules were drastically reduced and more single granules filled the endosperm cells of ospk2. Meanwhile, the germination rate of ospk2 seeds after 1‐year storage was observably reduced compared with wild‐type. Map‐based cloning of OsPK2 indicated that it encodes a pyruvate kinase (PK, ATP: pyruvate 2‐O‐phosphotransferase, EC 2.7.1.40), which catalyses an irreversible step of glycolysis. OsPK2 has a constitutive expression in rice and its protein localizes in chloroplasts. Enzyme assay showed that the protein product from expressed OsPK2 and the crude protein extracted from tissues of wild‐type exhibits strong PK activity; however, the mutant presented reduced protein activity. OsPK2 (PKpα1) and three other putative rice plastidic isozymes, PKpα2, PKpβ1 and PKpβ2, can interact to form heteromer. Moreover, the mutation leads to multiple metabolic disorders. Altogether, these results denote new insights into the role of OsPK2 in plant seed development, especially in starch synthesis, compound granules formation and grain filling, which would be useful for genetic improvement of high yield and rice grain quality. [ABSTRACT FROM AUTHOR]

Rice grain filling determines grain weight, final yield and grain quality. Here, a rice defective grain filling mutant, gif2, was identified. Grains of gif2 showed a slower filling rate and a significant lower final grain weight and yield compared to wild-type. The starch content in gif2 was noticeably decreased and its physicochemical properties were also altered. Moreover, gif2 endosperm cells showed obvious defects in compound granule formation. Positional cloning identified GIF2 to encode an ADP-glucose pyrophosphorylase (AGP) large subunit, AGPL2; consequently, AGP enzyme activity in gif2 endosperms was remarkably decreased. GIF2 is mainly expressed in developing grains and the coded protein localizes in the cytosol. Yeast two hybrid assay showed that GIF2 interacted with AGP small subunits OsAGPS1, OsAGPS2a and OsAGPS2b. Transcript levels for granule-bound starch synthase, starch synthase, starch branching enzyme and starch debranching enzyme were distinctly elevated in gif2 grains. In addition, the level of nucleotide diversity of the GIF2 locus was extremely low in both cultivated and wild rice. All of these results suggest that GIF2 plays important roles in the regulation of grain filling and starch biosynthesis during caryopsis development, and that it has been preserved during selection throughout domestication of modern rice. [ABSTRACT FROM AUTHOR]

Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV–vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400–640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect. [ABSTRACT FROM AUTHOR]

Background: An ideal appearance is of commercial value for rice varieties. Chalkiness is one of the most important appearance quality indicators. Therefore, clarification of the heredity of chalkiness and its molecular mechanisms will contribute to reduction of rice chalkiness. Although a number of QTLs related to chalkiness were mapped, few of them have been cloned so far. Results: In this study, using recombinant inbred lines (RILs) of PA64s and 9311, we identified 19 QTLs associated with chalkiness on chromosomes 1, 4, 6, 7, 9 and 12, which accounted for 5.1 to 30.6 % of phenotypic variations. A novel major QTL qACE9 for the area of chalky endosperm (ACE) was detected in Hainan and Hangzhou, both mapped in the overlapping region on chromosome 9. It was further fine mapped to an interval of 22 kb between two insertion-deletion (InDel) markers IND9-4 and IND9-5 using a BCF population. Gene prediction analysis identified five putative genes, among which only one gene ( OsAPS1), whose product involved in starch synthesis, was detected two nucleotide substitutions causing amino acid change between the parents. Significant difference was found in apparent amylose content (AAC) between NIL qACE9 and 9311. And starch granules were round and loosely packed in NIL qACE9 compared with 9311 by scanning electron microscopy (SEM) analysis. Conclusions: OsAPS1 was selected as a novel candidate gene for fine-mapped qACE9. The candidate gene not only plays a critical role during starch synthesis in endosperm, but also determines the area of chalky endosperm in rice. Further cloning of the QTL will facilitate the improvement of quality in hybrid rice. [ABSTRACT FROM AUTHOR]

We constructed an all-solid-state g-C 3 N 4 /Au/P25 Z-scheme system combining graphitic carbon nitride (g-C 3 N 4 ) and P25 with Au nanoparticles, as an electron mediator, for hydrogen production under visible-light irradiation ( λ > 400 nm). The g-C 3 N 4 /Au/P25 system was characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL), time-resolved photoluminescence (TRPL), and electrochemical measurements. TEM and high-resolution transmission electron microscopy (HRTEM) clearly reveal the morphology and structure of g-C 3 N 4 /Au/P25, implying the existence of the all-solid-state Z-scheme system. The results of electrochemical impedance spectroscopy (EIS) and TRPL indicate that the Z-scheme system can effectively promote the electron transfer rate and the separation of photogenerated electron–hole pairs for the vectorial electron transfer of P25→Au→g-C 3 N 4 . The Z-scheme system can also extend the visible light absorption wavelength from 460 to 700 nm due to the surface plasmon resonance (SPR) effect of Au nanoparticles, which is confirmed by UV–Vis DRS and incident photo-to-current efficiency (IPCE) measurements. The synergistic effect of the all-solid-state g-C 3 N 4 /Au/P25 Z-scheme system and the Au-induced SPR results in a highly efficient photocatalytic performance with a turnover frequency (TOF) of 259 μmol h −1 g −1 , which is 30 times higher than that of pristine g-C 3 N 4 . [ABSTRACT FROM AUTHOR]

Conclusion: This study developed an easy way to induce otitis media in an animal model and find the relation between tensor veli platini muscle (TVP) and levetor veli platini muscle (LVP) in the opening and closing of the pharyngeal orifice of Eustachian tube. It was proved that otitis media is caused due to the dysfunction of Eustachian tube and the only muscle responsible for opening and closing of ETPO (Eustachian tube pharyngeal orifice) is TVP and LVP has no role in the opening and closing of the Eustachian tube pharyngeal orifice. Objective: To develop valid animal model for otitis media of effusion and to study the relation of paratubular muscles in the functioning of Eustachian tube. Methods: Two different methods were used to induce middle ear disease: (1) Excision of tensor veli platini and levetor veli platini muscles (TVP and LVP); and (2) Injection of botulinum toxin type A on TVP and LVP. Result: Otomiscroscopic, tympanograph, and pathological examination showed the presence of middle ear disease in those animals whose TVP was excised and paralyzed, but on those groups of animals whose LVP was excised and paralyzed, abnormalities were seen. [ABSTRACT FROM PUBLISHER]

Rapid pericarp browning results in a short shelf life of postharvest litchi fruit. In this study, the impact of fluopyram (Flu) on litchi pericarp browning and possible mechanisms were investigated. Results showed that application of 0.2 % (v/v) fluopyram (Flu) delayed litchi pericarp browning during storage at 25 °C. Respiration rate and tricarboxylic acid (TCA) cycle were reduced in Flu-treated fruit, as indicated by the decreased succinate dehydrogenase (SDH) and α-ketoglutarate dehydrogenase (α-KGDH) activities. Meanwhile, Flu treatment resulted in higher succinic acid content but lower fumaric acid and α-ketoglutarate contents compared to those in non-Fu-treated fruit. Furthermore, Flu pretreatment maintained higher glutamate (Glu) level via enhancing glutamate dehydrogenase (GDH) activity. Additionally, Flu treatment accelerated gamma-aminobutyric acid (GABA)-shunt pathway by regulating GABA content and activities of glutamate decarboxylase (GAD) as well as GABA transaminase (GABA-T). Importantly, higher ATP and GTP contents were observed in Flu-treated fruit. Taken together, these results suggested that Flu treatment inhibited respiration but accelerated GABA-shunt pathway, which might contribute to higher energy status and thus attenuate litchi pericarp browning. This study provided new insights of Flu application in quality maintenance and shelf life extension of postharvest fruit storage. • Fluopyram (Flu) delayed pericarp browning of harvested litchi fruit. • Flu inhibited TCA cycle but induced gamma-aminobutyric acid (GABA)-shunt pathway. • Flu maintained higher energy status in harvested litchi fruit. [ABSTRACT FROM AUTHOR]

Aril breakdown results in the loss of nutrition and commodity value, thereby limits the postharvest storage of longan fruit. Histone deacetylases (HDACs) are important epigenetic regulators in many biological processes. Results in the current study showed that application of valeric acid (VA), which belongs to HDAC inhibitors, suppressed longan aril breakdown during postharvest storage. Meanwhile, lower contents of malondialdehyde, H 2 O 2 , and O 2 −., but higher activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) were observed in VA-treated fruit. Western blotting (WB) assay confirmed enhancement of histone H3 and H4 acetylation in VA-treated fruit, suggesting the possible inhibition of HDAC activity by VA. Furthermore, VA regulated DlHDACs expressions , with DlHDA5 and DlHDA8 expressions apposite of WB results. These results revealed that VA inhibited longan aril breakdown through enhancing the reactive oxygen species scavenging ability in relation to HDAC inhibitor activity. Our findings suggested that VA treatment delayed aril breakdown of longan fruit in relation to histone deacetylase-mediated epigenetic regulation and highlighted DlHDA5 and DlHDA8 potentially be important candidates for further research. • Valeric acid (VA) acts as a histone deacetylases (HDAC) inhibitor to suppress longan aril breakdown. • VA enhances the reactive oxygen species scavenging ability. • VA modulates histone H3 and H4 acetylation levels of longan aril. • VA regulates DlHDACs expressions. [ABSTRACT FROM AUTHOR]