Concentration and localization of zinc during seed development and germination in wheat

In a field experiment, the effect of foliar Zn applications on the concentration of Zn in seeds of a bread wheat cultivar (Triticum aestivum L. cv. Balatilla) was studied during different stages of seed development. In addition, a staining method using dithizone (DTZ: diphenyl thiocarbazone) was applied to (1) study the localization of Zn in seeds, (2) follow the remobilization of Zn during germination, and (3) develop a rapid visual Zn screening method for seed and flour samples. In all seed development stages, foliar Zn treatments were effective in increasing seed Zn concentration. The highest Zn concentration in the seeds was found in the first stage of seed development (around the early milk stage); after this, seed Zn concentration gradually decreased until maturity. When reacting with Zn, DTZ forms a redcolored complex. The DTZ staining of seed samples revealed that Zn is predominantly located in the embryo and aleurone parts of the seeds. After 36 h of germination, the coleoptile and roots that emerged from seeds showed very intensive red color formation and had Zn concentrations up to 200 mg kg1, indicating a substantial remobilization of Zn from seed pools into the developing roots (radicle) and coleoptile. The DTZ staining method seems to be useful in ranking flour samples for their Zn concentrations. There was a close relationship between the seed Zn concentrations and spectral absorbance of the methanol extracts of the flour samples stained with DTZ. The results suggest that (1) accumulation of Zn in seeds is particularly high during early seed development, (2) Zn is concentrated in the embryo and aleurone parts, and (3) the DTZ staining method can be used as a rapid, semiquantitative method to estimate Zn concentrations of flour and seed samples and to screen genotypes for their Zn concentrations in seeds

The arogenate dehydratase ADT2 is essential for seed development in Arabidopsis

Phenylalanine (Phe) biosynthesis in plants is a key process, as Phe serves as precursor of proteins and phenylpropanoids. The prephenate pathway connects chorismate, final product of the shikimate pathway, with the biosynthesis of Phe and Tyr. Two alternative routes of Phe biosynthesis have been reported: one depending of arogenate, and the other of phenylpyruvate. Whereas the arogenate pathway is considered the main route, the role of the phenylpyruvate pathway remains unclear. Here, we report that the deficiency in ADT2, a bifunctional arogenate dehydratase (ADT)/ prephenate dehydratase (PDT) enzyme, causes embryo arrest and seed abortion. This result makes a clear distinction between the essential role of ADT2 and the five remaining ADTs from Arabidopsis, which display mostly overlapping functions. We have found that PHA2, a monofunctional PDT from yeast, restores the adt2 phenotype when is targeted within the plastids, but not when is expressed in the cytosol. Similar results can be obtained by expressing ADT3, a monofunctional ADT. These results suggest that Phe can be synthesized from phenylpyruvate or arogenate when the bifunctional ADT2 is replaced by other ADT or PDT enzymes during seed formation, highlighting the importance of Phe for embryo development, and providing further insights into the plasticity of Phe biosynthesis.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sterol concentration and distribution in sunflower seeds (Helianthus annuus L.) during seed development

Sunflower seeds are currently used for edible oil production. Among oil minor compounds, phytosterols are of special interest due to their cholesterol reducing properties. This paper reports studies on their accumulation and distribution in the embryo and hull, and the effects of temperature on phytosterol contents in sunflower seed produced under both conventional and organic field conditions. An optimized method of sterol determination, adapted to studies on small samples of seed, is presented. Seventy-two % of phytosterols were found in the embryo, 28 % in the hull. The periods of phytosterols concentration varied according to sterol category and seed part. Application of these results to improve production of natural sterols for functional food use is discussed

REGULATORY NETWORKS DURING SEED DEVELOPMENT

Seeds make up approximately 70% of the human diet directly so understanding regulatory mechanisms to generate a seed and the embryo it contains is fundamentally important. The LAFL genes encode transcription factors (TF) that are critical for seed development. Three members of LAFL, LEAFY COTYLEDON2 (LEC2), ABSCISIC ACID3 (ABI3) and FUSCA3 (FUS3), are B3 domain factors that bind DNA motifs called RY motifs. While LEC2 is expressed earlier in embryo development, ABI3 and FUS3 are expressed during later development. All three of these TFs can induce embryo-specific programs after completion of germination to different extents up to and including formation of embryos in a process called somatic embryogenesis (SE). ABI3 also contributes to the abscisic acid (ABA) response. Prior work determined direct and indirect targets of FUS3. Here we report on chromatin immunoprecipitation-tiling array experiments to globally map binding sites for ABI3. We also assessed transcriptomes in response to ABI3 by comparing developing abi3-5 and wild type seeds and combine this information to ascertain direct and indirect responsive ABI3 target genes. ABI3 can directly induce and repress its target genes’ transcript accumulation and some intriguing differences exist in cis motifs between these groups of genes. Directly regulated targets reflect ABI3’s roles in seed maturation, desiccation tolerance, entry into a quiescent state and longevity. Interestingly, ABI3 directly represses a gene encoding a microRNA (MIR160B) that targets AUXIN RESPONSE FACTOR (ARF)10 and ARF16 that are involved in establishment of dormancy. In addition, ABI3, like FUS3, regulates genes encoding MIR156 but while FUS3 only induces genes encoding this product, ABI3 induces these genes during early stages of seed development, but represses these genes during late development. The interplay between ABI3, the other LAFL genes, and the VP1/ABI3-LIKE (VAL) genes that are involved in the transition to seedling development are examined and reveal complex interactions controlling development. ABI3 directly regulates all five DUF1264 (Domain of Unknown Function 1264) members in Arabidopsis, while two other seed transcription factors FUS3 and AGL15 directly control subsets of genes in this family. Arabidopsis genes designated as DUF1264s appear to be expressed specifically within seeds and the encoded protein include a domain of unknown function that is highly conserved in various plants. Here, the direct association of the TFs with these genes and effect on transcript accumulation is verified. Also, higher order mutants were generated. Quadruple duf1264 mutant shows a reduction in SE compared to wild type control. Pentuple duf1264 mutant shows a hypersensitive response in seedlings to ABA compared to WT. In an associated project, an Arabidopsis protein called SIN3A associated polypeptide 18 (AtSAP18) was investigated. SAP18 is a transcriptional co-regulator that is a component of histone deacetylase (HDAC) complexes which interacts with a TF of interest in the lab, AGL15 to control embryogenesis. A new phenotype of a loss-of-function mutant sap18 was documented in that the mutant is hypersensitive to ABA treatment compared to Columbia (Col) wild type (WT), suggesting an important role of SAP18 in modulation of ABA response. Finally, the global targets of AGL15 were identified by combining previous RNA microarrays and ChIP microarrays with RNA-seq and ChIP-seq in this study. Also, some of these regulatory networks were investigated in the important crop plant, Glycine max

Novel developments in SBGN-ED and applications

Systems Biology Graphical Notation (SBGN, http://sbgn.org) [1] is an emerging standard for graphical representations of biochemical and cellular processes studied in systems biology. Three different views (Process Description, Entity Relationship, and Activity Flow) cover several aspects of the represented processes in different levels of detail. SBGN helps to communicate biological knowledge more efficient and accurate between different research communities in the life sciences. However, to support SBGN, methods and tools for editing, validating, and translating of SBGN maps are necessary.
We present methods for these tasks and novel developments in SBGN-ED (www.sbgn-ed.org) [2], a tool which allows to create all three types of SBGN maps from scratch, to validate these maps for syntactical and semantical correctness, to translate maps from the KEGG database into SBGN, and to export SBGN maps into several file and image formats. SBGN-ED is based on VANTED (Visualization and Analysis of NeTworks containing Experimental Data, http://www.vanted.org) [3].
As applications of SBGN and SBGN-ED we present furthermore MetaCrop (http://metacrop.ipk-gatersleben.de) [4], a database that summarizes diverse information about metabolic pathways in crop plants, and RIMAS (Regulatory Interaction Maps of Arabidopsis Seed Development, http://rimas.ipk-gatersleben.de) [5], an information portal that provides a comprehensive overview of regulatory pathways and genetic interactions during Arabidopsis embryo and seed development. 

[1] Le Novère, N. et al. (2009) The Systems Biology Graphical Notation. Nature Biotechnology, 27, 735-741.
[2] Czauderna, T., Klukas, C., Schreiber, F. (2010) Editing, validating, and translating of SBGN maps. Bioinformatics, 26 (18), 2340-2341.
[3] Junker, B.H., Klukas, C., Schreiber, F. (2006) VANTED: A system for advanced data analysis and visualization in the context of biological networks. BMC Bioinformatics, 7, 109+.
[4] Grafahrend-Belau, E., Weise, S., Koschützki, D., Scholz, U., Junker, B.H., Schreiber, F. (2008) MetaCrop - A detailed database of crop plant metabolism. Nucleic Acids Research, 36, D954-D958.
[5] Junker, A., Hartmann, A., Schreiber, F., Bäumlein, H. (2010) An engineer's view on regulation of seed development. Trends in Plant Science, 15(6), 303-307.
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Decoding the Transcriptome of Rice Seed During Development

Rice seed development is a continuous process wherein it undergoes complex molecular and tissue reprogramming. It is a collective effect of embryo and endosperm development, each of which undertakes its own developmental paths, with endosperm development significantly affecting embryo. Understanding the mechanistics of the regulatory networks administrating this process is the building block for any future research on grain yield and quality. High-throughput transcript profiling and small RNA profiling studies have proved useful in providing information about the molecular changes occurring in various tissues associated with seed development. Transcriptome sequencing studies have highlighted the significant genes and pathways that are operating during seed development. The involvement of TFs and hormones has also been implicated in regulating key aspects of seed development, including embryo patterning and seed maturation. This chapter will review the information provided by high-throughput sequencing studies on various aspects of rice seed development, highlighting the developmental complexities of embryo and endosperm

Phenotypic Characterization of the Arabidopsis ufm1 (Ubiquitin Fold Modifier) Gene Involved in Seed Development

Background and Objective: With the completion of the Arabidopsis genome sequencing, the next challenge is the determination ofgene function. Post-translational modifications of proteins by small polypeptide are implicated in plant growth and development.Ubiquitin fold modifier 1 is a member of the ubiquitin like protein family. While, the enzymatic conjugation cascade of ubiquitin foldmodifier 1 has been elucidated in recent years, its biological role is still unknown. The present study focuses in elucidate the role of theufm1 in plants development. Materials and Methods: The researchers performed analyses of the development of wild-type Columbiaplants and mutants of the ubiquitin fold modifier 1 gene to identify and interpret phenotypic changes in plants and seeds. Data werestatistically analyzed with the Info Stat software. Results: In this study, evidence suggesting that ubiquitin fold modifier 1 is involved inthe normal development of the seeds. Conclusion: The ufm1 gene would affect the normal development of the seed, particularly of theembryo, causing high percentage of seed abortion.Fil: Cornejo, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Masuelli, Ricardo Williams. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin

A study of effects of low temperature stress on seed development and yield in wheat (Triticum aestivam L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Seed Technology at Massey University

Temperature affects the growth, development, fertility and yield of cereals. The degree of sterility and subsequent yield reduction caused by extreme temperature stress depends upon the minimum level and duration of the stress temperature applied and the stage of plant development at the time of stress. An experiment was conducted in which three low temperature regimes (-4°, -2°C and +3°C) were applied at 5 different stages of plant growth (from 1 day before anthesis to 9 days after anthesis) for a period of 6 hours with pre- and post- conditioning periods of 6 and 4 hours respectively. The results showed that the minimum temperature reached determined the nature and severity of temperature injury in Karamu wheat. Complete floret sterility was evident when a -4°C temperature was imposed at the pre-anthesis or anthesis stages of plant development; florets in any position of the head being equally affected. A -4°C temperature stress applied 3 days after anthesis produced 50% and 5% seed formation in primary and secondary heads, respectively. This seed formation mainly occurred in the basal florets of the apical and central spikelets of the head, however the seeds formed did not develop after stress and subsequent viable seed yield was zero. At the later stages, 6 or 9 days after anthesis a -4°C temperature stress had no significant effect on seed numbers. However there was a substantial negative effect on seed development and viability so that subsequent viable seed yield was zero. Temperature stresses of +3°C and -2°C had no significant effects on seed formation, development and viable seed yield when stresses were applied at any of the stages of plant development tested. The percentage of seed formation was highest in the two basal florets of the central and apical portions of the head compared to that in the two basal florets of the bottom of the head and to the distal florets of all spikelets. The percentage sterility in terms of relative sterility (percentage 'D + R' type ovules) and sterility index (percentage 'D' type ovules) was also described. It was found that in 'Karamu' wheat 16% to 33% rudimentary florets were a common feature, such structures included tiny basal, sterile spikelets and the terminal florets of all spikelets. Morphological and anatomical differences in ovules harvested at different stages of development from different treatments were observed. Ovules were classified into 6 groups for assessment of seed development. (A = apparently not fertilised, B = swollen and conical shaped, C = developing, D = shrivelled and shrunken, E = shrunken with reduced conical shape, R = rudimentary). Possible pathways to seed formation and development can be estimated from the data. A probable pathway to normal seed development is A to B to C. However, in the case of unsuccessful seed formation and development, the pathway is likely to be A to D,A to B to D or A to B to C to D. Further detailed electron microscope work is needed to enable a complete description and understanding of the pathways of seed development in stressed and unstressed plants. Such knowledge is needed to provide a logical basis for the development of cultivars with increased cold tolerance, fertility and yield

Pengaruh Beberapa Dosis Pupuk Fosfor (P) terhadap Mutu Benih Berbagai Kultivar Kedelai (Glycine Max L. Merril) Selama Pengisian dan Pemasakan Biji

An experiment has been designed to investigate the impact of Phosphorous (P) fertilizer on seed quaaliti during seed development of several Soybean (Glycine max L. Merrill) cultivars. The field experiment was carried at University of Riau Agriculture Experiment Station using a complete randomized block design with three replicates. Soybean cultivars such as Willis, Malabar, Kipas Putih and line KM-19-BE were planted in three rates of P fertilizer; ie P0 = 0 kg P2O5 as a control, P1 = 25 kg P2O5, and P2 = 50 kg P2O5 per hektare. Seed quality including seed viability and seed vigor was observed at 10 days interval from 20 to 50 days after anthesis (DAA). It was found that seed quality was very low at early stage of seed development and tent to reach its maximum value as seed matured. Addition of P fertilizer to the plant increased some components of seed quality at early stage of seed development until 40 DAA. The values of seed viability and seed vigor were higher in seed harvested from plant fertilized by P than control, mainly for seed obtained at early seed development. This results indicated that P fertilizer application would improve seed quality especially of seed harvested at early seed development of some soybean cultivars