Post-Transcriptional Gene Regulation during Seed Germination and Stand Establishment

Seed germination and stand establishment are critical steps in production of horticultural crops. Valuable phenotypes integrated into commercial varieties of horticultural crops through breeding programs cannot be expressed properly in fields or greenhouses, if the initial steps of plant growth are not successful. Therefore, it is essential to ensure successful seed germination and stand establishment. Recent progress in basic research has advanced our understanding of the mechanisms of seed germination and post-germination. Data obtained from transcriptome analyses have provided much information concerning the transcriptional control in seeds and seedlings. In contrast, posttranscriptional control during germination and stand establishment has not been studied extensively. One of the foci in our laboratory is to examine the role of microRNA (miRNA)-targeted genes during germination and early seedling development. Two of these genes are discussed in this paper. AUXIN RESPONSE FACTOR10, a target of miR160, plays an important role in abscisic acid-auxin crosstalk in imbibed seeds. SQUAMOSA PROMOTER-BINDING PROTEIN LIKE13 (SPL13), a target of miR156, affects development of vegetative leaves in young seedlings. Down-regulation of transcription factors by miRNAs appears to play a critical role in seed germination and stand establishment.