The APETALA1/SQUAMOSA (AP1/SQUA)-like genes of flowering plants play crucial roles in the development processes of floral meristems, sepals, petals and fruits. Although many of the AP1/SQUA-like genes have been characterized in angiosperms, few have been identified in basal angiosperm taxa. Therefore, the functional evolution of the AP1/SQUA subfamily is still unclear. We characterized an AP1 homolog, MawuAP1, from Magnolia wufengensis that is an ornamental woody plant belonging to the basal angiosperms. Gene sequence and phylogenetic analyses suggested that MawuAP1 was clustered with the FUL-like homologous genes of basal angiosperms and had FUL motif and paleoAP1 motif domain, but it did not have the euAP1 motif domain of core eudicots. Expression pattern analysis showed that MawuAP1 was highly expressed in vegetative and floral organs, particularly in the early stage of flower bud development and pre-anthesis. Protein–protein interaction pattern analysis revealed that MawuAP1 has interaction with an A-class gene (MawuAP1), C-class gene (MawuAG-1) and E-class gene (MawuAGL9) of the MADS-box family genes. Ectopic expression in Arabidopsis thaliana indicated that MawuAP1 could significantly promote flowering and fruit development, but it could not restore the sepal and petal formation of ap1 mutants. These results demonstrated that there are functional differences in the specification of sepal and petal floral organs and development of fruits among the AP1/SQUA-like genes, and functional conservation in the regulation of floral meristem. These findings provide strong evidence for the important functions of MawuAP1 in floral meristem determination, promoting flowering and fruit development, and further highlight the importance of AP1/SQUA subfamily in biological evolution and diversity.

中文翻译：

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MawuAP1促进基础被子植物五峰木兰（木兰科）的开花和果实发育。

开花植物的APETALA1 / SQUAMOSA（AP1 / SQUA）样基因在花卉分生组织，萼片，花瓣和果实的发育过程中起关键作用。尽管在被子植物中已鉴定出许多类似AP1 / SQUA的基因，但在被子植物基类中却很少被鉴定。因此，AP1 / SQUA亚家族的功能进化仍不清楚。我们表征了五峰木兰的AP1同源物MawuAP1，它是属于基被子植物的观赏木本植物。基因序列和系统发育分析表明，MawuAP1与FUL聚类与基础被子植物类似的同源基因，具有FUL基序和paleoAP1基序域，但没有核心双子叶植物的euAP1基序域。表达模式分析表明，MawuAP1在营养和花器官中高表达，特别是在花蕾发育和花前期的早期。蛋白质-蛋白质相互作用模式分析表明，MawuAP1与MADS-box家族基因的A类基因（MawuAP1），C类基因（MawuAG-1）和E类基因（MawuAGL9）有相互作用。拟南芥中的异位表达表明MawuAP1可以显着促进开花和果实发育，但不能恢复ap1突变体的萼片和花瓣形成。这些结果表明，AP1 / SQUA样基因在萼片和花瓣花器官的规格和果实发育上有功能差异，在花分生组织的调节上有功能保守性。这些发现为MawuAP1在确定花卉分生组织，促进开花和果实发育中的重要功能提供了有力的证据，并进一步强调了AP1 / SQUA亚科在生物进化和多样性中的重要性。