High-temporal-resolution Transcriptome Landscape of Early Maize Seed Development.

The early maize (Zea mays) seed undergoes several developmental stages after double fertilization to become fully differentiated within a short period of time, but the genetic control of this highly dynamic and complex developmental processes remains largely unknown. Here, we report a high-temporal-resolution investigation of transcriptomes using 31 samples collected at an interval of 4 or 6 hours within the first six days of seed development. These time-course transcriptomes were clearly separated into four distinct groups, corresponding to the stages of double fertilization, coenocyte formation, cellularization, and differentiation. A total of 22,790 expressed genes including 1,415 transcription factors (TFs) were detected in early stages of maize seed development. In particular, 1,093 genes including 110 TFs were specifically expressed in the seed and displayed high temporal specificity by expressing only in particular period of early seed development. There were 160, 22, 112 and 569 seed-specific genes predominantly expressed in the first 16 hours after pollination, coenocyte formation, cellularization and differentiation stage, respectively. In addition, network analysis predicted 31,256 interactions among 1,317 TFs and 14,540 genes. The high-temporal-resolution transcriptome atlas reported here provides an important resource for future functional study to unravel the genetic control of seed development.