A Novel Protective Mechanism of PdSOS1 in Exerting Its Salt Tolerance Function in Peach

The peach rootstock Prunus davidiana exhibits salt stress resistance and therefore is often used as parental material for breeding; however, the mechanism underlying salt tolerance in P. davidiana remains unclear. In the present study, we identified PdSOS1 in the peach genome that showed a similarity with the Arabidopsis thalianaATNHX7 gene at the DNA level. PdSOS1 was found to be a positive regulator enhancing the salt tolerance of P. davidiana and could interact with two proteins, PdSINAT and PdAE7. Furthermore, PdSINAT ubiquitinated and degraded PdSOS1 and negatively regulated salt tolerance in P. davidiana. The interaction regions in PdSINAT-PdSOS1 and PdAE7-PdSOS1 were the same. We demonstrated that PdAE7 enhanced the stability of PdSOS1 and prevented its ubiquitination and degradation by PdSINAT. In conclusion, the present work provides novel insights into the molecular mechanism related to salt tolerance in P. davidiana, providing a molecular foundation for salt-tolerant peach breeding.