Investigating the Molecular, Physiological, and Architectural Changes that underlie Grafting-Induced Vigor

Grafting has been used to increase yield, especially in the context of biotic and abiotic stress for over 2000 years. Although recent experimental evidence suggests that non-cell autonomous long-distance signals may play an important role in the mechanism through which grafting impacts plant growth and physiology, the precise identity of these signals and the mechanisms by which they act to affect yield remain largely unexplored. In tomato, the grafting of elite fruit producing shoots (scions) onto vigorous, interspecific hybrid root systems significantly increases yield. We demonstrate that grafting-induced vigor can be reciprocally transferred between the root and shoot systems of an interspecific hybrid (Solanum lycopersicum x S. habrochaites) and domesticated (S. lycopersicum) tomatoes. We are combining morphological and physiological measurements of reciprocally grafted root and shoot systems with RNA-seq profiling for non-cell autonomous graft-transmissible transcripts that may serve as molecular signals through which grafting-induced vigor is conferred. This molecular network is being overlaid with QTL mapping of genetic factors that contribute towards grafting-induced vigor using a defined set of S. habrochaites introgression lines.