An ETHYLENE INSENSITIVE3-LIKE1 Protein Directly Targets the Promoter and Mediates Ethylene-Induced Ray Petal Elongation in .

Petal morphogenesis has a profound influence on the quality of ornamental flowers. Most current research on petal development focuses on the early developmental stage, and little is known about the late developmental stage. Previously, it was reported that the gene [a gerbera homolog of the gibberellin-stimulated transcript 1 () from tomato] negatively regulates ray petal growth during the late stage of development by inhibiting longitudinal cell expansion. To explore the molecular mechanisms of the role of in petal growth inhibition, an ethylene insensitive 3-like 1 (EIL1) protein was identified from a cDNA library by yeast one-hybrid screening. Direct binding between GhEIL1 and the promoter was confirmed by electrophoretic mobility shift and dual-luciferase assays. The expression profiles of and were correlated during petal development, while a transient transformation assay suggested that GhEIL1 regulates expression and may be involved in the inhibition of ray petal elongation and cell elongation. To study the effect of ethylene on ray petal growth, a hormone treatment assay was performed in detached ray petals. The results showed that petal elongation is limited and promoted by ACC and 1-MCP, respectively, and the expression of and is regulated and coordinated during this process. Taken together, our research suggests that GhEIL1 forms part of the ethylene signaling pathway and activates to regulate ray petal growth during the late developmental stage in .