Why Tomato and Pepper Can't Get Along: New Study Reveals Immune Battle at Graft Site
Grafting between different plant species can offer advantages like disease resistance and structural resilience. However, graft incompatibility remains a biological mystery. This study uncovers the molecular basis behind the long-standing incompatibility between tomato and various pepper cultivars. Through detailed anatomical analysis and transcriptomic profiling, researchers discovered that tomato-pepper grafts fail to form proper vascular bridges and instead activate strong immune responses. These responses are marked by persistent cell death, upregulation of nucleotide-binding leucine-rich repeat receptors (NLRs), and genes associated with DNA damage and programmed cell death. The findings suggest that tomato and pepper identify each other as "non-self," triggering a defense mechanism that undermines graft success.