Project description:Soybean (Glycine max) seeds are an important source of seed storage compounds, including protein, oil, and sugar used for food, feed, chemical, and biofuel production. We assessed detailed temporal transcriptional and metabolic changes in developing soybean embryos to gain a systems biology view of developmental and metabolic changes and to identify potential targets for metabolic engineering. Two major developmental and metabolic transitions were captured enabling identification of potential metabolic engineering targets specific to seed filling and to desiccation. The first transition involved a switch between different types of metabolism in dividing and elongating cells. The second transition involved the onset of maturation and desiccation tolerance during seed filling and a switch from photoheterotrophic to heterotrophic metabolism. Clustering analyses of metabolite and transcript data revealed clusters of functionally related metabolites and transcripts active in these different developmental and metabolic programs. The gene clusters provide a resource to generate predictions about the associations and interactions of unknown regulators with their targets based on "guilt-by-association" relationships. The inferred regulators also represent potential targets for future metabolic engineering of relevant pathways and steps in central carbon and nitrogen metabolism in soybean embryos and drought and desiccation tolerance in plants.
Project description:Soybean (Glycine max) is an important crop providing oil and protein for both human and animal consumption. Knowing which biological processes take place in specific tissues in a temporal manner will enable directed breeding or synthetic approaches to improve seed quantity and quality. We analyzed a genome-wide transcriptome dataset from embryo, endosperm, endothelium, epidermis, hilum, outer and inner integument and suspensor at the global, heart and cotyledon stages of soybean seed development. The tissue specificity of gene expression was greater than stage specificity, and only three genes were differentially expressed in all seed tissues. Tissues had both unique and shared enriched functional categories of tissue-specifically expressed genes associated with them. Strong spatio-temporal correlation in gene expression was identified using weighted gene co-expression network analysis, with the most co-expression occurring in one seed tissue. Transcription factors with distinct spatiotemporal gene expression programs in each seed tissue were identified as candidate regulators of expression within those tissues. Gene ontology (GO) enrichment of orthogroup clusters revealed the conserved functions and unique roles of orthogroups with similar and contrasting expression patterns in transcript abundance between soybean and Arabidopsis during embryo proper and endosperm development. Key regulators in each seed tissue and hub genes connecting those networks were characterized by constructing gene regulatory networks. Our findings provide an important resource for describing the structure and function of individual soybean seed compartments during early seed development.
Project description:Developing soybean seeds accumulate oils, proteins, and carbohydrates that are used as oxidizable substrates providing metabolic precursors and energy during seed germination. The accumulation of these storage compounds in developing seeds is highly regulated at multiple levels, including at transcriptional and post-transcriptional regulation. RNA sequencing was used to provide comprehensive information about transcriptional and post-transcriptional events that take place in developing soybean embryos. Bioinformatics analyses lead to the identification of different classes of alternatively spliced isoforms and corresponding changes in their levels on a global scale during soybean embryo development. Alternative splicing was associated with transcripts involved in various metabolic and developmental processes, including central carbon and nitrogen metabolism, induction of maturation and dormancy, and splicing itself. Detailed examination of selected RNA isoforms revealed alterations in individual domains that could result in changes in subcellular localization of the resulting proteins, protein-protein and enzyme-substrate interactions, and regulation of protein activities. Different isoforms may play an important role in regulating developmental and metabolic processes occurring at different stages in developing oilseed embryos.
Project description:We used laser capture microdissection (LCM) to capture soybean seed compartments and profiled the transcriptomes of several compartments using next-generation sequencing. We profiled the transcriptomes of the embryo-proper and the suspensor region from globular stage embryos and the seed coat parenchyma layer of early maturation stage seeds using the Illumina GAIIx system. Illumina sequencing of transcripts from laser-captured embryo proper and suspensor of globular stage embryo and seed coat parenchyma layer of the early maturation stage seed.
Project description:Soybean is a rich source of protein and oil and a primary feedstock for biodiesel production. Previous research on soybean indicated that protein, oil and yield are controlled quantitatively in soybean seeds. However, genetic mechanisms controlling seed composition and yield in soybean remain unknown. We used Affymetrix Soybean GeneChips® to identify genes that are differentially expressed between developing seeds of the Minsoy and Archer soybean varieties, which differ in seed weight, yield, protein content and oil content. Some of the differentially expressed genes identified in this study may play important roles in controlling these traits. Overall design: The soybean plants of two soybean varieties Minsoy and Archer and two recombinant inbred lines from the cross that are similar in maturity but differ in yield were grown in St Paul, Minnesota during the summers of 2007 and 2008. In 2007, each line was planted as a single row. In 2008, a randomized complete block (RCB) design was used and each line had 3 replicates planted 1-2 weeks apart. Within each replicate, two rows per line were planted. Seeds were harvested at three developmental stages, namely, seed length = 2 mm, 3.5 mm, and 5-6 mm, which correspond approximately to soybean reproductive stages R4, R5 and early R6, respectively. In 2007 three independent samples were collected for each line and developmental stage. In 2008, two seed samples (one from each row) were collected for each line at each stage within each replicate. The pairs of seed samples were then pooled. Thus, three sets of independent tissue samples were collected for RNA extraction and hybridization on Affymetrix microarrys.
Project description:A transcriptome analysis of soybean seeds harvested at different developing stages (between stage 7.1 and stage 9) was carried out to understand the molecular events occuring during the acquisition of seed longevity during maturation. Overall design: RNAseq from developing Glycine max seeds from stage 7.1 (mid-seedfilling) to final maturation