Dwarfing Rootstock ‘Yunnan’ Quince Promoted Fruit Sugar Accumulation by Influencing Assimilate Flow and PbSWEET6 in Pear Scion

‘Yunnan’ quince (Cydonia oblonga Mill.) is used as the dwarfing rootstock for pear (Pyrus spp.). Here, we reported that sugar contents in mature ‘Zaosu’ fruit grafted on ‘Yunan’ (Z/Q) were higher than ‘Duli’ betulifolia) (Z/D). To investigate underlying mechanism, leaf photosynthetic capacity and leaf-to-fruit assimilate transport initially analyzed. The was similar between Z/Q Z/D, but greater Z/D. Sugar transporters mediate distribution of assimilates; therefore, changes PbSWEET transcriptional patterns examined. PbSWEET6 highly expressed fruit. Thus, function related to further verified. Sucrose glucose increased transgenic tomato calli overexpressing PbSWEET6. Taken together, these results suggest positively regulated by influencing flow PbSWEET6-involved assimilates scion.