ABSTRACT
KEY MESSAGE: Os4BGlu14, a monolignol ß-glucosidase, plays a negative role in seed longevity by affecting primary metabolism during seed development and aging. Seed longevity is a crucial trait in agriculture and in the conservation of germplasm resources. ß-Glucosidases (BGlus) are multifunctional enzymes that affect plant growth and their adaptation to the environment. The function of rice BGlus in seed longevity, however, remains unknown. We report here that Os4BGlu14, a rice ß-Glucosidase, negatively affected seed longevity during accelerated aging. Os4BGlu14 was highly expressed in rice embryos and induced by accelerated aging. Compared to the wild type, rice lines overexpressing Os4BGlu14 had significantly greater grain length, but smaller grain width and thickness. Overexpressing (OE) lines also showed lower starch but higher glucose contents. After accelerated aging treatment, OE lines displayed a significantly lower germination percentage than the wild type. Additionally, these lines had higher lignin accumulation before and after accelerated aging. Metabolome analysis detected 217 metabolites in untreated and aged rice seeds. Comparison of the differential metabolites between WT and OE5 revealed that ten key metabolites, four of which (e.g., uridine 5'-diphosphoglucose-glucose, UDPG) were increased, while the other six (e.g., γ-aminobutyric acid and methionine) were decreased, might be the crucial factors that lead to seed deterioration. Further analysis confirmed higher UDPG levels and more severe programmed cell death in OE lines than in the wild type. Furthermore, OE lines presented a lower germination rate after abscisic acid and paclobutrazol treatment during germination, compared to the wild type. Our study provides a basis for understanding the function of Os4BGlu14 in seed longevity in rice.
Subject(s)
Oryza/genetics , Oryza/metabolism , Plant Proteins/genetics , Seeds/physiology , beta-Glucosidase/genetics , Abscisic Acid/pharmacology , Cell Death , Gene Expression Regulation, Plant , Germination/drug effects , Lignin/genetics , Lignin/metabolism , Metabolome , Oxidative Stress/physiology , Plant Cells/physiology , Plant Proteins/metabolism , Plants, Genetically Modified , Seeds/metabolism , Uridine Diphosphate Glucose/metabolism , beta-Glucosidase/metabolismABSTRACT
Semidwarfism is an important agronomic trait in rice breeding programs. The semidwarf mutant gene Sdt97 was previously described. However, the molecular mechanism underlying the mutant is yet to be elucidated. In this study, we identified the mutant gene by a map-based cloning method. Using a residual heterozygous line (RHL) population, Sdt97 was mapped to the long arm of chromosome 6 in the interval of nearly 60 kb between STS marker N6 and SNP marker N16 within the PAC clone P0453H04. Sequencing of the candidate genes in the target region revealed that a base transversion from G to C occurred in the 5' untranslated region of Sdt97 qRT-PCR results confirmed that the transversion induced an obvious change in the expression pattern of Sdt97 at different growth and developmental stages. Plants transgenic for Sdt97 resulted in the restoration of semidwarfism of the mutant phenotype, or displayed a greater dwarf phenotype than the mutant. Our results indicate that a point mutation in the 5' untranslated region of Sdt97 confers semidwarfism in rice. Functional analysis of Sdt97 will open a new field of study for rice semidwarfism, and also expand our knowledge of the molecular mechanism of semidwarfism in rice.
Subject(s)
5' Untranslated Regions , Genes, Plant , Oryza/genetics , Point Mutation , Quantitative Trait, Heritable , Base Sequence , Breeding , Chromosome Mapping , Cloning, Molecular , DNA Mutational Analysis , Gene Expression Regulation, Plant , Genetic Association Studies , Genotype , Phenotype , Plants, Genetically Modified , Polymorphism, Single NucleotideABSTRACT
A new electrostatically self-assembled film has successfully been prepared on quartz and indium-tin-oxide (ITO) substrates by alternating adsorption of [BW11Zn(H2O)O39](7-) (BW11Zn) and a hemicyanine of (E)-1,1'-(hexane-1,6-diyl)bis(4-(4-(dimethylamino)styryl)pyridinium) bromide (H6Br2). The UV-visible absorption spectra showed that the film was uniformly deposited and the interaction between the two film-forming components occurred in the film. The (BW11Zn/H6)n film exhibited stable cathodic photocurrent as irradiated with white light. The photocurrents were found to increase linearly with increasing the deposited bilayers increased up to 3 layers. The photocurrent action spectrum indicated that the cathodic photocurrents were generated from charge transfer excitation of H6 in the (BW11Zn/H6)n film. The effects of applied bias voltages, electron donor and acceptor added in the electrolyte, and layer number n of (BW11Zn/H6)n film on the photocurrent generation have also been examined.
