Assistant Research Fellow Academia Sinica Tainan City, Tainan, Taiwan (Republic of China)
Body of Abstract: The morphogenesis occurs in embryogeny and post-germination in higher plants. These two morphogenesis events are connected by a period of developmental arrest, which is characterized by the cessation of cell differentiation and division. Meanwhile, sequential biological processes occur, including maturation, desiccation, dormancy, and germination. These developmental processes are underpinned by successively expressed gene sets, indicating transcriptional processes control developmental events in embryos and seedlings. Therefore, the major questions are: what genes are sequentially expressed, and how are genes coordinately regulated to progress the transitions of developmental programs? However, gene expression patterns and interconnections among genes throughout the developmental stages between the two morphogenesis events in embryonic and post-germinative development, especially in economically important crops, are relatively unknown. To address this, we analyzed the transcriptomes from 12 soybean seed stages bridging the two morphogenesis events in embryogeny and post-germination. Analysis of this considerable time course enabled the identification of consecutively active gene sets and gene regulatory networks promoting the transitions of developmental processes. For instance, we found that a gene regulatory network is preferentially provoked in the early desiccation stage and contains many transcription factors involved in the response to abiotic stress. Further functional examination of one transcription factor highly active in this desiccation-related gene network validated the predictive regulatory network. Furthermore, we uncovered that a specific set of soybean genes, recognized for being highly active in germination or their capacity to induce germination in Arabidopsis seeds, are active not only in germination but also during the late differentiation, maturation, and/or desiccation stages of soybean seed development. This implies that these genes may contribute to shaping the dormancy type, physical dormancy, in soybean seeds, in contrast to the physiological dormancy in Arabidopsis. This study illustrates the genetic basis underlying the transitions of developmental programs across embryogeny and post-germination in soybean seeds.