Recently, Associate Professor Fengkai Wu from the Maize Research Institute published a research article as the first author in the prestigious plant science journal The Plant Cell (Impact Factor = 11.6), entitled “The Blue Light Receptor ZmFKF1a Recruits ZmGI1 to the Nucleus to Accelerate Shoot Apex Development and Flowering in Maize.”
To evaluate the expression patterns of light-responsive genes, maize seedlings were cultivated in Jiupo plant growth chambers equipped with controlled climate systems and optimized plant lighting. This study is the first to reveal a novel mechanism by which the blue-light receptor ZmFKF1a promotes maize flowering, providing critical theoretical support for overcoming the photoperiod constraints that hinder temperate maize introduction and adaptation.
Through genome-wide association analysis, ZmFKF1a was identified as being significantly associated with anthesis-silking interval (ASI) in maize. Using CRISPR–Cas9 to generate zmfkf1a mutants in the tropical maize background KN5585, researchers observed a pronounced flowering delay under both natural long-day (NLD) and natural short-day (NSD) conditions, whereas ZmFKF1a overexpression led to accelerated flowering.
ChIP–qPCR and dual-luciferase assays demonstrated that the rhythmic expression of ZmFKF1a is directly regulated by the Evening Complex (EC) component ZmLUX2. Results from Y2H, BiFC, and Co-IP assays confirmed that ZmFKF1a specifically interacts with ZmGI1 under blue light, enhancing ZmGI1 stability and nuclear localization. This interaction is strictly blue-light dependent, disappearing under darkness or red-light conditions.
Within the nucleus, ZmGI1 directly binds to and activates the promoter of ZMM4, a MADS-box gene expressed in the shoot apical meristem, thereby driving floral meristem differentiation. Genetic epistasis analysis indicated that ZmGI1 acts downstream of ZmFKF1a. Notably, this pathway operates independently of the classical ZCN florigen pathway: expression of ZCN8 was unaffected in zmfkf1a and zmgi1 mutants, and ZMM4 overexpression partially rescued the late-flowering phenotype of zmgi1.
In the photoperiod-sensitive tropical maize line CML312, overexpression of ZmFKF1a markedly improved flowering synchrony and grain yield under extremely long-day conditions.
ZmFKF1a mediates blue light–dependent nuclear localization of ZmGI1, which activates ZMM4 to drive shoot apex development and flowering. This establishes a ZmLUX2–ZmFKF1a–ZmGI1–ZMM4 regulatory module, independent of the ZCN pathway.
More importantly, functional validation in tropical inbred maize lines revealed that ZmFKF1a overexpression not only significantly shortens the growth period but also synchronously enhances yield. This discovery provides a key genetic resource and theoretical basis for the efficient utilization of tropical maize germplasm in temperate regions and for the breeding of broadly adaptable, high-yield maize varieties.
Figure. Proposed model of ZmFKF1a-mediated regulation of shoot apex development and flowering in maize.
Author Information
Fengkai Wu, Associate Professor at Sichuan Agricultural University, Yan Kang (Ph.D. candidate), and Ling Liu (Ph.D., now Associate Professor at Yibin University) are co–first authors. Professor Yanli Lu of Sichuan Agricultural University is the corresponding author. Significant contributions were made by Dr. Xuecai Zhang (International Maize and Wheat Improvement Center, CIMMYT) and Dr. Qingguo Du (Institute of Crop Science, Chinese Academy of Agricultural Sciences).
This study was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the Sichuan Provincial Natural Science Foundation.