is Upregulated by LncRNA5 and Controls Branch Number in Peach () Through Positive Feedback Regulation of Strigolactone Biosynthesis

Branch number is an important agronomic trait in peach () trees because plant architecture affects fruit yield and quality. Although breeders can select varieties with different tree architecture, the biological mechanisms underlying architecture remain largely unclear. In this study, a pillar peach ('Zhaoshouhong') and a standard peach ('Okubo') were compared. 'Zhaoshouhong' was found to have significantly fewer secondary branches than 'Okubo'. Treatment with the synthetic strigolactone (SL) GR24 decreased branch number. Transcriptome analysis indicated that (a homologous gene of ) expression was negatively correlated with strigolactone synthesis gene expression, indicating that may play an important role in peach branching. Yeast one-hybrid, electrophoretic mobility shift, dual-luciferase assays and -knockdown in peach leaf buds indicated that PpTCP18 could increase expression of , and . Furthermore, transgenic Arabidopsis plants overexpressing clearly exhibited reduced primary rosette-leaf branches. Moreover, lncRNA sequencing and transient expression analysis revealed that lncRNA5 targeted , significantly increasing expression. These results provide insights into the mRNA and lncRNA network in the peach SL signaling pathway and indicate that PpTCP18, a transcription factor downstream of SL signaling, is involved in positive feedback regulation of SL biosynthesis. This role of PpTCP18 may represent a novel mechanism in peach branching regulation. Our study improves current understanding of the mechanisms underlying peach branching and provides theoretical support for genetic improvement of peach tree architecture.