Development of genetically modified sweet cherry rootstock 'Gisela 6' with overexpression of PcMPK3-HA gene by Agrobacterium-mediated genetic transformation

Key message New germplasms of cherry rootstocks 6 overexpressing the recombinant gene PcMPK3-HA were obtained. Genetic engineering is an efficient technique to improve target traits and provide a potential impetus for germplasm innovation of cherry rootstocks. In this study, we used cherry rootstock 'Gisela 6' (Prunus cerasus x Prunus canescens) as the receptor for Agrobacterium-mediated genetic transformation and introduce the recombinant gene PcMPK3-HA into 'Gisela 6' rootstock. In addition, we identified phenotypes during the formation of adventitious roots in transgenic lines. The results showed that a combination of 2.0 mg L-1 6-benzylaminopurine (BAP) and 1.0 mg L-1 indole-3-butyric acid (IBA) effectively induced regeneration of 'Gisela 6' leaf explants. Selective pressure was a key factor affecting the efficiency of regeneration and transformation. We obtained 19 kanamycin-resistant buds of cherry rootstock and polymerase chain reaction (PCR) revealed five positive buds. Southern blotting confirmed that the PcMPK3-HA gene was integrated into the genome of transgenic lines. Quantitative reverse transcriptase-PCR (qRT-PCR) confirmed significantly higher expression of the PcMPK3 gene in transgenic lines than in wild-type 'Gisela 6'. Phenotypic analysis showed that the overexpression of PcMPK3-HA enhanced the formation of adventitious roots in transgenic rootstocks, and exerted a positive effect on root growth in tissue-cultured rootstocks following transplantation. Altogether, new germplasms of cherry rootstocks overexpressing PcMPK3-HA were obtained using Agrobacterium-mediated genetic transformation method.