Constitutive overexpression of GRF21, a 14-3-3 family protein, delays flowering time in maize (Zea mays).
TL;DR
Findings implicate GRF21 as a negative regulator of flowering time in maize, as evidenced by the delayed flowering phenotype associated with its overexpression, and highlights GRF21 as a promising target for maize breeding.
Abstract
Background
Flowering time represents a pivotal agronomic trait that determines regional adaptability and grain yield in maize (Zea mays). Members of the 14-3-3 protein family, also known as general regulatory factors (GRFs), function as central modulators of diverse developmental and physiological processes in plants. However, their specific roles in regulating flowering time in maize remain undefined.
Results
Here, we present a functional characterization of GRF21, a maize GRF family member, with particular emphasis on its role in floral transition. Through an integrative approach combining phylogenetic analysis, gene transformation, and genome-wide transcriptomic analysis, we show that constitutive overexpression of GRF21 delays flowering in maize, suggesting a potential role in flowering-time regulation. GRF21 localizes to both the nucleus and cytoplasm and accumulates predominantly in roots, stems, and reproductive tissues. Furthermore, transcriptomic analyses, supported by quantitative RT-PCR and dual-luciferase reporter assays, reveal that GRF21 represses the transcription of key flowering-promoting genes, including Zea mays CENTRORADIALIS 7 (ZCN7), ZCN8, and ZCN12, thereby suppressing floral transition.
Conclusions
Collectively, these findings implicate GRF21 as a negative regulator of flowering time in maize, as evidenced by the delayed flowering phenotype associated with its overexpression. This work expands the current molecular framework underlying floral initiation and highlights GRF21 as a promising target for maize breeding.