Phosphorus (P) is an essential mineral nutrient required for the plant growth and development. Insufficient P supply triggers extensive physiological and biochemical changes in plants. In this study, we used Affymetrix GeneChip rice genome arrays to analyze the dynamics of rice transcriptome under P starvation. Phosphorus starvation induced or suppressed transcription of 2,317 genes, representing 7.2% of the genes. These changes, mostly transient, affected various cellular metabolic pathways including stress response, primary and secondary metabolism, molecular transport, regulatory process and organismal development. Hundred and thirty (5.6% of 2,317 genes) transcripts were expressed similarly both in root and shoot under P starvation. Comparative analysis between rice and Arabidopsis identified 37 orthologous groups that responded to P starvation demonstrating the existence of conserved P stress coupling mechanism among dicot and monocot plants. Additional analysis of transcription profiles of microRNAs revealed differential expression of miR399 and miR169 under P starvation suggesting their potential roles in plant nutrient homeostasis. Analysis of genome-wide gene expression profiles in P starvation in rice shoot and root, using Affymetrix Rice Genome Chip in this paper, has provided an overview of transcriptional responses to the P starvation condition. This will bring very valuable information and will make a great contribution for investigating the response of rice to P starvation.
Nitrogen (N) is one of the most important limiting factors for plant growth and development. Amino acids are the major source of organic N, which is converted from inorganic N absorbed by plant roots from the soil. Amino acid transporters are the principal mediators of organic N distribution and important regulators of resource allocation in plants. Although the complete genomic sequence of rice has already been released, there is still little known about amino acid transporter genes in rice. In this study, 79 OsAAT genes were identified by a database search of the rice genome based upon HMM profiles. A bioinformatics analysis of the complete set of OsAAT genes is presented, including chromosomal location, phylogenetic analysis, gene structure, protein analysis, conserved motifs, protein structures and cis-element analysis of the promoters. In addition, the comprehensive expression profile of OsAAT genes in rice tissues/organs under N starvation conditions was investigated by real-time PCR analysis. Diverse expression patterns of OsAAT genes indicated diverse biological functions of the amino acid transporters and the important roles of OsAAT genes in N uptake, metabolism and distribution during N starvation. The evaluation of yield and carbon (C) and N content of osaat knockout mutants also suggested the important roles of the OsAAT5, OsAAT7, OsAAT24, OsAAT49 and OsAAT60 genes in yield and biomass production and C and N metabolism and distribution in rice plants.
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In this study, we fabricated ZnO nanostructures using bamboo fibers as templates. The starting material used was zinc acetate, and the nanostructures were synthesized by soaking and calcining the bamboo fibers. The fabricated nanostructures were characterized using X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and ultraviolet-visible spectrophotometry. The results showed that the size of the ZnO nanoparticles was approximately 20–100 nm. When the ZnO nanoparticles were used as the catalyst in the photodegradation of methyl orange, the dye degraded by 95.98 % in 80 min. The response and recovery times of a gas sensor based on the ZnO nanoparticles were 25 and 24 s, respectively, during the detection of C2H5OH in a concentration of 10 ppm at 270 °C.