The MADS transcription factor GhAP1 coordinates the flowering regulatory pathway in upland cotton (Gossypium hirsutum L.)

Abstract Background: MADS-box gene family plays an important role in the molecular regulatory network of flower development. APETAL1 (AP1), a MADS-box gene, plays an important role in the development of flower organs. Although many studies about MADS-box family genes have been reported, the function of AP1 is still not clear in cotton. Results: In this study, GhAP1 (Gh_D03G0922), a candidate gene for cotton flower time and plant height obtained from our previous studies, was cloned from CCRI50 cotton variety and functionally characterized. Subcellular localization demonstrated that GhAP1 was located in nucleus. Infection test of Arabidopsis revealed that GhAP1 could cause precocious flowering and virus-induced gene silence (VIGS) assay demonstrated that GhAP1 could lead to delayed flowering of cotton plants. Yeast one-hybrid assays and transient dual-luciferase assays suggested that floral meristem identity control gene LEAFY (LFY) can bind the promoter of GhAP1 and negatively regulate it. Yeast two-hybrid assays suggested that GhAP1 can interact with pyridoxal phosphate (PLP)-dependent transferases superfamily protein PSAT2. Conclusions: Our research indicated that GhAP1 might work as a positive regulator in plant flowering. Moreover, GhAP1 may interact with GhPSAT2 and be negatively regulated by GhLFY in the regulatory pathways. This work laid the foundation for subsequent functional studies of GhAP1.