RcPLATZ8 as a novel negative regulator of flowering in Rosa chinensis.

Comprehensive analysis of the RcPLATZ gene family in Rosa chinensis reveals RcPLATZ8 as a novel negative regulator of flowering, offering insights for targeted breeding to manipulate flowering traits. Flowering regulation in Rosa chinensis is essential for improving ornamental and commercial traits, but its molecular mechanisms remain poorly understood. In this study, we identified and characterized ten members of the PLANT AT-RICH SEQUENCE AND ZINC-BINDING (PLATZ) protein family in R. chinensis through genome-wide analysis and protein domain validation using the Pfam database. Among these, we focused on RcPLATZ8, a novel negative regulator of flowering. Expression analysis via RT-qPCR revealed that RcPLATZ8 is predominantly expressed in floral organs, including stamens, pistils, and petals, and exhibits significant responsiveness to key plant hormones, such as abscisic acid (ABA), gibberellins (GA), and jasmonic acid (JA). Functional assays showed that overexpression of RcPLATZ8 in Arabidopsis resulted in delayed flowering and increased leaf number, whereas silencing RcPLATZ8 in R. chinensis led to early flowering. Furthermore, Weighted Gene Co-expression Network Analysis (WGCNA) identified that RcPLATZ8 is part of the 'red module,' which is strongly associated with flowering-time regulatory genes, including SHORT VEGETATIVE PHASE (SVP). These findings provide new insights into the molecular regulation of flowering in roses, demonstrating that RcPLATZ8 may plays a key role in integrating hormonal signals and floral development. Our study not only expands the functional understanding of the PLATZ family but also offers potential strategies for molecular breeding aimed at improving flowering traits for horticultural applications.