摘要：
Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid(Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase(L-Gal LDH, EC1.3.2.3) is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the L-Gal LDH-overexpressing transgenic rice, GO-2,which has constitutively higher leaf Asc content than wild-type(WT) plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate(Asc/DHA)ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate(Ru BP) carboxylase/oxygenase(Rubisco) protein level in GO-2 at 80 days. In addition, levels of abscisic acid(ABA) and jasmonic acid(JA) were lower in GO-2 at 60, 80, and100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the L-Gal LDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling.
摘要：
Plant architecture, a complex of the important agronomic traits that determine grain yield, is a primary target of artificial selection of rice domestication and improvement. Some important genes affecting plant architecture and grain yield have been isolated and characterized in recent decades; however, their underlying mechanism remains to be elucidated. Here, we report genetic identification and functional analysis of the PLANT ARCHITECTURE AND YIELD 1 (PAY1) gene in rice, which affects plant architecture and grain yield in rice. Transgenic plants over-expressing PAY1 had twice the number of grains per panicle and consequently produced nearly 38% more grain yield per plant than control plants. Mechanistically, PAY1 could improve plant architecture via affecting polar auxin transport activity and altering endogenous indole-3-acetic acid distribution. Furthermore, introgression of PAY1 into elite rice cultivars, using marker-assisted background selection, dramatically increased grain yield compared with the recipient parents. Overall, these results demonstrated that PAY1 could be a new beneficial genetic resource for shaping ideal plant architecture and breeding high-yielding rice varieties.
摘要：
Plant architecture is an important factor for crop production. Some members of microRNA156 (miR156) and their target genes SQUAMOSA Promoter-Binding Protein-Like (SPL) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T-DNA insertion mutant Osmtd1 (Oryza sativa multi-tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T-DNA insertion in Osmtd1. Further analysis revealed that the T-DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild-type rice phenocopied Osmtd1. We showed that the expression of OsSPL3, OsSPL12, and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3, OsSPL12, and OsSPL14 were possibly direct target genes of OsmiR156f. Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.
摘要：
The competitive immunoreaction technique for the detection of 2,4-dichlorophenoxyacetic acid(2,-4D) was described in this paper based on quartz crystal microbalance (QCM) with gold nanoparticles enhanced surfaces. The results showed the response of the sensor has a good linear relationship with 2,4-D concentrations in the range of 13.3-666.7 ng/mL with a detection limit at about 13.0 ng/mL. This work also provides a promising alternative approach for immuno-detection of other small molecules. The sensor could be regenerated under mild conditions simply by immersing the sensor into glycine buffer solution to break the antibody-antigen linkage. It was found that the proposed sensor could be reused at least nine runs without obvious loss of sensitivity. (C) 2013 Elsevier B.V. All rights reserved.
摘要：
Reactive oxygen species and auxin play important roles in the networks that regulate plant development and morphogenetic changes. However, the molecular mechanisms underlying the interactions between them are poorly understood. This study isolated a mas (More Axillary Shoots) mutant, which was identified as an allele of the mitochondrial AAA-protease AtFtSH4, and characterized the function of the FtSH4 gene in regulating plant development by mediating the peroxidase-dependent interplay between hydrogen peroxide (H2O2) and auxin homeostasis. The phenotypes of dwarfism and increased axillary branches observed in the mas (renamed as ftsh4-4) mutant result from a decrease in the IAA concentration. The expression levels of several auxin signaling genes, including IAA1, IAA2, and IAA3, as well as several auxin binding and transport genes, decreased significantly in ftsh4-4 plants. However, the H2O2 and peroxidases levels, which also have IAA oxidase activity, were significantly elevated in ftsh4-4 plants. The ftsh4-4 phenotypes could be reversed by expressing the iaaM gene or by knocking down the peroxidase genes PRX34 and PRX33. Both approaches can increase auxin levels in the ftsh4-4 mutant. Taken together, these results provided direct molecular and genetic evidence for the interaction between mitochondrial ATP-dependent protease, H2O2, and auxin homeostasis to regulate plant growth and development.
摘要：
MAX2 (for MORE AXILLARY GROWTH2) has been shown to regulate diverse biological processes, including plant architecture, photomorphogenesis, senescence, and karrikin signaling. Although karrikin is a smoke-derived abiotic signal, a role for MAX2 in abiotic stress response pathways is least investigated. Here, we show that the max2 mutant is strongly hypersensitive to drought stress compared with wild-type Arabidopsis (Arabidopsis thaliana). Stomatal closure of max2 was less sensitive to abscisic acid (ABA) than that of the wild type. Cuticle thickness of max2 was significantly thinner than that of the wild type. Both of these phenotypes of max2 mutant plants correlate with the increased water loss and drought-sensitive phenotype. Quantitative real-time reverse transcription-polymerase chain reaction analyses showed that the expression of stress-responsive genes and ABA biosynthesis, catabolism, transport, and signaling genes was impaired in max2 compared with wild-type seedlings in response to drought stress. Double mutant analysis of max2 with the ABA-insensitive mutants abi3 and abi5 indicated that MAX2 may function upstream of these genes. The expression of ABA-regulated genes was enhanced in imbibed max2 seeds. In addition, max2 mutant seedlings were hypersensitive to ABA and osmotic stress, including NaCl, mannitol, and glucose. Interestingly, ABA, osmotic stress, and drought-sensitive phenotypes were restricted to max2, and the strigolactone biosynthetic pathway mutants max1, max3, and max4 did not display any defects in these responses. Taken together, these results uncover an important role for MAX2 in plant responses to abiotic stress conditions.
摘要：
An automatic versatile system which integrated solid phase extraction (SPE) with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed. Diverse commercial SPE columns can be used under an ambient pressure in this online system realized by a dual-dilution strategy. The first dilution enabled the direct injection of complex samples with minimal pretreatment, and the second dilution realized direct introduction of large volume of strong eluent into the UHPLC column without causing peak broadening or distortion. In addition, a post-column compensation mode was also designed for the matrix-effects evaluation. The features of the online system were systematically investigated, including the dilution effect, the capture of desorption solution, the column-head stacking effect and the system recovery. Compared with the offline UHPLC system, this online system showed significant advantages such as larger injection volume, higher sensitivity, shorter analysis time and better repeatability. The feasibility of the system was demonstrated by the direct analysis of three auxins from different plant tissues, including leaves of Dracaena sanderiana, buds and petals of Bauhinia. Under the optimized conditions, the whole analysis procedure took only 7 min. All the correlation coefficients were greater than 0.9987, the limits of detection and the limits of quantitation were in the range of 0.560-0.800 ng/g and 1.80-2.60 ng/g, respectively. The recoveries of the real samples ranged from 61.0 to 117%. Finally, the post-column compensation mode was applied and no matrix-effects were observed under the analysis conditions. The automatic versatile system was rapid, sensitive and reliable. We expect this system could be extended to other target analytes in complex samples utilizing diverse SPE columns. (C) 2014 Elsevier B.V. All rights reserved.
期刊：
EuPA Open Proteomics,2014年4:40-57 ISSN：2212-9685
通讯作者：
Ma, H.
作者机构：
[Hongyu Ma; Liru Song; Yan Yang; Shuang Wang; Zhankui Wang; Hao Ma] State Key Laboratory of Crop Genetics and Germplasm Enhancement, National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, PR China;[Zhigang Huang; Jianhua Tong; Langtao Xiao] Hunan Provincial Key Laboratory of Phytohormones, Hunan Agricultural University, Changsha, Hunan Province 410128, PR China;[Weihong Gu] Animal and Plant Introduction and Research Center, Shanghai Agricultural Academy, Shanghai 201106, PR China
通讯机构：
[Ma, H.] S;State Key Laboratory of Crop Genetics and Germplasm Enhancement, National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
关键词：
Metabolism;Proteomics;Salt stress;Salt tolerant and sensitive;Soybean
摘要：
The 12-oxo-phytodienoic acid reductases (OPRs) are classified into the two subgroups OPRI and OPRII. The latter proteins participate in jasmonic acid synthesis, while the function of the former ones is as yet unclear. We describe here the characterization of the OPRI gene TaOPR1, isolated from the salinity-tolerant bread wheat (Triticum aestivum) cultivar SR3. Salinity stress induced a higher level of TaOPR1 expression in the seedling roots of cv SR3 than in its parental cultivar, JN177. This induction was abolished when abscisic acid (ABA) synthesis was inhibited. The overexpression of TaOPR1 in wheat significantly enhanced the level of salinity tolerance, while its heterologous expression in Arabidopsis alleviated root growth restriction in the presence of salinity and oxidants and raised the sensitivity to ABA. In Arabidopsis, TaOPR1 promoted ABA synthesis and the ABA-dependent stress-responsive pathway, partially rescued the sensitivity of the Arabidopsis aba2 mutant defective in ABA synthesis to salinity, and improved the activities of reactive oxygen species scavengers and the transcription of their encoding genes while reducing malondialdehyde and reactive oxygen species levels. TaOPR1 did not interact with jasmonate synthesis or the jasmonate signaling pathway. Rather than serving purely as an antioxidant, we believe that TaOPR1 acts during episodes of abiotic stress response as a signaling compound associated with the regulation of the ABA-mediated signaling network.
关键词：
Ascorbic acid;L-Galactono-1,4-lactone dehydrogenase;Rice;Senescence;Tiller number
摘要：
The tiller of rice (Oryza sativa L.), which determines the panicle number per plant, is an important agronomic trait for grain production. Ascorbic acid (Asc) is a major plant antioxidant that serves many functions in plants. L-Galactono-1,4-lactone dehydrogenase (GLDH, EC 1.3.23) is an enzyme that catalyzes the last step of Asc biosynthesis in plants. Here we show that the GLDH-suppressed transgenic rices, GI-1 and GI-2, which have constitutively low (between 30% and 50%) leaf Asc content compared with the wild-type plants, exhibit a significantly reduced tiller number. Moreover, lower growth rate and plant height were observed in the Asc-deficient plants relative to the trait values of the wild-type plants at different tillering stages. Further examination showed that the deficiency of Asc resulted in a higher lipid peroxidation, a loss of chlorophyll, a loss of carotenoids, and a lower rate of CO2 assimilation. In addition, the level of abscisic acid was higher in GI-1 plants, while the level of jasmonic acid was higher in GI-1 and GI-2 plants at different tillering stages. The results we presented here indicated that Asc deficiency was likely responsible for the promotion of premature senescence, which was accompanied by a marked decrease in photosynthesis. These observations support the conclusion that the deficiency of Asc alters the tiller number in the GLDH-suppressed transgenics through promoting premature senescence and changing phytohormones related to senescence. (C) 2012 Elsevier GmbH. All rights reserved.
