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MADS‐box transcription factors (TFs) play indispensable roles in various aspects of plant growth, development as well as in response to environmental stresses. Several MADS‐box genes have been reported to be involved in the salt tolerance in different plant species. However, the role of the transcription factor OsMADS57 under salinity stress is still unknown. Here, the results of this study showed that OsMADS57 was mainly expressed in roots and leaves of rice plants (Oryza sativa). Gene expression pattern analysis revealed that OsMADS57 was induced by NaCl. Overexpression of OsMADS57 in both Arabidopsis thaliana (A. thaliana) and rice could improve their salt tolerance, which was demonstrated by higher germination rates, longer root length and better growth status of overexpression plants than wild type (WT) under salinity conditions. In contrast, RNA interference (RNAi) lines of rice showed more sensitivity towards salinity. Moreover, less reactive oxygen species (ROS) accumulated in OsMADS57 overexpressing lines when exposed to salt stress, as measured by 3, 3′‐diaminobenzidine (DAB) or nitroblue tetrazolium (NBT) staining. Further experiments exhibited that overexpression of OsMADS57 in rice significantly increased the tolerance ability of plants to oxidative damage under salt stress, mainly by increasing the activities of antioxidative enzymes such as superoxide dismutase (SOD) and peroxidase (POD), reducing malonaldehyde (MDA) content and improving the expression of stress‐related genes. Taken together, these results demonstrated that OsMADS57 plays a positive role in enhancing salt tolerance by activating the antioxidant system. [ABSTRACT FROM AUTHOR]

Rice is the staple food of almost half of the world population, and in excess 90% of it is grown and consumed in Asia, but the disposal of rice straw poses a problem for farmers, who often burn it in the fields, causing health and environmental problems. However, with increased focus on the development of sustainable biofuel production, rice straw has been recognized as a potential feedstock for non-food derived biofuel production. Currently, the commercial realization of rice as a biofuel feedstock is constrained by the high cost of industrial saccharification processes needed to release sugar for fermentation. This study is focused on the alteration of lignin content, and cell wall chemotypes and structures, and their effects on the saccharification potential of rice lignocellulosic biomass. A recombinant inbred lines (RILs) population derived from a cross between the lowland rice variety IR1552 and the upland rice variety Azucena with 271 molecular markers for quantitative trait SNP (QTS) analyses was used. After association analysis of 271 markers for saccharification potential, 1 locus and 4 pairs of epistatic loci were found to contribute to the enzymatic digestibility phenotype, and an inverse relationship between reducing sugar and lignin content in these recombinant inbred lines was identified. As a result of QTS analyses, several cell-wall associated candidate genes are proposed that may be useful for marker-assisted breeding and may aid breeders to produce potential high saccharification rice varieties. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the effect of bisphenol A (BPA) on rice seedlings grown in a hydroponic system. The obtained results demonstrated that at lower concentration (up to 10 µM) BPA had some stimulatory effects on the growth of rice seedlings but at higher doses it significantly inhibited seedlings growth. The photosynthetic pigments were significantly decreased by high doses of BPA. Exposure to BPA caused increased membrane permeability in root cells and resulted in increased concentration of reactive oxygen species (ROS) and increased lipid peroxidation as revealed by thiobarbituric acid reactive substances (TBARS) assay. In leaves, superoxide dismutase (SOD) activity exhibited an increase at lower concentrations of BPA but was inhibited at the highest dose (200 µM) of BPA. At 100 µM of BPA, a significant increase in antioxidant activities in leaves was observed but at 200 µM this activity was inhibited. In roots, a significant decrease in enzymes activity was recorded at the highest concentration of BPA (200 µM); however, ascorbate peroxidase (APX) and catalase (CAT) activities were significantly increased at the concentrations of 10 and 50 µM in comparison to the control. Moreover, the present results revealed that BPA severely affected cell organelles in rice seedlings. It can be concluded that the observed adverse effects in rice seedlings by BPA in the present study could be attributed to the oxidative stress caused by BPA. [ABSTRACT FROM AUTHOR]

MADS-box transcription factors are vital regulators participating in plant growth and development process and the functions of most of them are still unknown. ANR1 was reported to play a key role in controlling lateral root development through nitrate signal in Arabidopsis. OsMADS25 is one of five ANR1-like genes in Oryza Sativa and belongs to the ANR1 clade. Here we have investigated the role of OsMADS25 in the plant’s responses to external nitrate in Oryza Sativa. Our results showed that OsMADS25 protein was found in the nucleus as well as in the cytoplasm. Over-expression of OsMADS25 significantly promoted lateral and primary root growth as well as shoot growth in a nitrate-dependent manner in Arabidopsis. OsMADS25 overexpression in transgenic rice resulted in significantly increased primary root length, lateral root number, lateral root length and shoot fresh weight in the presence of nitrate. Down-regulation of OsMADS25 in transgenic rice exhibited significantly reduced shoot and root growth in the presence of nitrate. Furthermore, over-expression of OsMADS25 in transgenic rice promoted nitrate accumulation and significantly increased the expressions of nitrate transporter genes at high rates of nitrate supply while down-regulation of OsMADS25 produced the opposite effect. Taken together, our findings suggest that OsMADS25 is a positive regulator control lateral and primary root development in rice. [ABSTRACT FROM AUTHOR]

The ANR1 MADS-box gene in Arabidopsis is a key gene involved in regulating lateral root development in response to the external nitrate supply. There are five ANR1-like genes in Oryza sativa, OsMADS23, OsMADS25, OsMADS27, OsMADS57 and OsMADS61, all of which belong to the AGL17 clade. Here we have investigated the responsiveness of these genes to fluctuations in nitrogen (N), phosphorus (P) and sulfur (S) mineral nutrient supply. The MADS-box genes have been shown to have a range of responses to the nutrient supply. The expression of OsMADS61 was transiently induced by N deprivation but was not affected by re-supply with various N sources. The expression of OsMADS25 and OsMADS27 was induced by re-supplying with NO3− and NH4NO3, but downregulated by NH4+. The expression of OsMADS57 was significantly downregulated by N starvation and upregulated by 3 h NO3− re-supply. OsMADS23 was the only gene that showed no response to either N starvation nor NO3− re-supply. OsMADS57 was the only gene not regulated by P fluctuation whereas the expression of OsMADS23, OsMADS25 and OsMADS27 was downregulated by P starvation and P re-supply. In contrast, all five ANR1-related genes were significantly upregulated by S starvation. Our results also indicated that there were interactions among nitrate, sulphate and phosphate transporters in rice. [ABSTRACT FROM AUTHOR]

The low seedling rate of rice caused by submergence in the process of rice direct seeding has always been an important factor limiting the popularization of rice direct seeding technology. Improving the tolerance of rice to submergence stress will benefit the production of rice and the promotion of direct seeding technology. In this study, we determined the submergence coleoptile length (SCL), submergence shoot length (SSL), and submergence tolerance index (STI) of 166 different cultivated rice seedlings as the phenotypes. Through the genome-wide association analysis (GWAS) of SCL, SSL, and STI, we found multiple quantitative trait locus (QTL) locations, including nine reported QTL locations. To narrow down the candidate gene numbers, we combined data from GWAS, transcriptomic analysis, gene function annotation, and reported QTL locations, and 50 candidate genes for submergence stress were obtained. Some reported genes had been firstly found to play certain roles in submergence-mediated growth response. Combining with reported RNA-seq data and expression profile data, we focused on four adjacent genes (LOC_Os11g47550, LOC_Os11g47570, LOC_Os11g47590, and LOC_Os11g47610) located in qAG11. RNA-seq and expression profile suggested the expression of these genes in sensitive and tolerant types differs hundreds of times (146~510 fold). Based on the diverse germplasms, we determined the natural haplotype of these genes. The haplotype analysis of these four genes showed a large genetic difference between indica and japonica. These results help us to better understand the molecular mechanism of natural variations in submergence tolerance among diverse germplasms and provide materials and new genes for further selection of new submergence tolerance varieties. [ABSTRACT FROM AUTHOR]