Over-Expression of ZmIAA29, an AUX/IAA Transcription Factor, Improved Maize Flowering Time

Maize is one of the most important food and feed crops in China due to the high demand for its use by both humans and animals. The Huang-Huai-Hai region is a major maize cultivation area in China, and the special cropping rotation system of wheat and maize requires a suitable reproductive period for maize. The AUX/IAA and ARF transcription factors are two key genes that regulate auxin signals in plants, which play an important role during the process of auxin regulation in plant growth and development. In this study, we obtained two overexpressed lines of ZmIAA29 belonging to the AUX/IAA transcription factor family. Compared with the Wide type, the overexpressed strains of ZmIAA29 were significantly regulated in maize during the flowering time and had increased ear weight. Moreover, ZmIAA29 was assayed via the yeast two-hybrid and BiLUC systems for interaction, and the results showed that ZmIAA29 interacted with several ZmARF transcription factors. Furthermore, RNA-seq and DAP-seq analysis revealed that ZmIAA29 regulates maize growth and development by influencing pathways such as those for plant signal transduction and the key genes related to maize flowering. Taken together, our results suggest that ZmIAA29 plays a key role in the development of maize flowering. This study provides new insight for better understanding the combined regulation of the AUX/IAA and ARF transcription factors during flowering time in maize.