Immediately following germination, the developing soybean plant relies on the nutrient reserves stored in the cotyledons to sustain heterotrophic growth. Likewise, a developing seed relies on the transport of nutrients from the trifoliate leaves. Before these tissues senesce, the nutrients must be mobilized and transported to other parts of the plant, such as the seed. We used an RNAseq approach
... [Show full abstract] to compare levels of gene expression throughout leaf and cotyledon development in Glycine max. Over 61,000 transcripts were found to be expressed during the course of both leaf and cotyledon development. Of those transcripts, 2,500 transcripts were expressed in a tissue specific pattern. Differentially expressed genes between two stages of leaf/cotyledon development were determined using three different packages, and shared genes were identified. Of the genes that were differentially expressed between both later stage tissues, 90% of them had the same directionally of change, suggesting that the mechanisms of senescence are conserved between tissues. Genes that were up regulated in the later stages include the transporters and genes involved with biotic stresses. Genes down-regulated during the later stages include genes involved with light reactions and nucleotide synthesis. From this we were able to divide the process of senescence into distinct stages.
