# PpGATA21 Enhances the Expression of PpGA2ox7 to Regulate the Mechanism of Cerasus humilis Rootstock-Mediated Dwarf in Peach Trees

## TL;DR

Cerasus humilis rootstocks cause dwarfing in peach trees by reducing gibberellin levels through the activation of PpGA2ox7 by PpGATA21.

## Contribution

Identifies PpGATA21 as a transcription factor that activates PpGA2ox7, linking GA metabolism to dwarfing in peach trees.

## Key findings

- PpGA2ox7 expression increases in Cerasus humilis grafted plants, correlating with reduced plant height and internode length.
- PpGATA21 binds to and activates the PpGA2ox7 promoter, leading to decreased gibberellin levels.
- Grafting onto Cerasus humilis significantly reduces GA levels and promotes dwarfing in peach trees.

## Abstract

Dwarfing rootstocks enhance planting density, lower tree height, and reduce both labor in peach production. Cerasus humilis is distinguished by its dwarf stature, rapid growth, and robust fruiting capabilities, presenting substantial potential for further development. In this study, Ruipan 4 was used as the scion and grafted onto Amygdalus persica and Cerasus humilis, respectively. The results indicate that compared to grafting combination R/M (Ruipan 4/Amygdalus persica), grafting combination R/O (Ruipan 4/Cerasus humilis) plants show a significant reduction in height and a significant increase in flower buds. RNA-seq indicates that genes related to gibberellin (GA) and auxin metabolism are involved in the dwarfing process of scions mediated by C. humilis. The expression levels of the GA metabolism-related gene PpGA2ox7 significantly increased in R/O and are strongly correlated with plant height, branch length, and internode length. Furthermore, GA levels were significantly reduced in R/O. The transcription factor PpGATA21 was identified through yeast one-hybrid screening of the PpGA2ox7 promoter. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) demonstrate that PpGATA21 can bind to the promoter of PpGA2ox7 and activate its expression. Overall, PpGATA21 activates the expression of the GA-related gene PpGA2ox7, resulting in reduced GA levels and consequent dwarfing of plants mediated by C. humilis. This study provides new insights into the mechanisms of C. humilis and offers a scientific foundation for the dwarfing and high-density cultivation of peach trees.