Hetero-top-grafting restricts phloem carbon transport and reprograms the graft union in citrus
Top-grafting is widely used for cultivar renewal in old citrus orchards, yet some hetero-top-grafting combinations show poor tree vigor and restricted growth. However, the physiological mechanisms underlying this growth limitation remain unclear. Here, we investigated carbon allocation, carbohydrate metabolism, phytohormone accumulation, anatomical structure, and multi-omics responses in citrus plants subjected to non-top-grafting, self-top-grafting, and hetero-top-grafting.