Exploring graft incompatibility markers: Intraspecific and interspecific grafts of tomato (Solanum lycopersicum L.)

Abstract

Grafting is an innovative and cost-efficient technique commonly practiced in solanaceous crops such as tomato (Solanum lycopersicum L.). However, incompatibility limits the far-reaching grafting approaches in sustainable food production worldwide. An early and precise graft incompatibility detection will have great significance, since graft compatibility between rootstock and scion is a pre-requisite for a successful grafting. The current study examined graft incompatibility in tomato self-grafts (Roma tomato grafted on Roma tomato), intraspecific grafts (Roma tomato grafted on Super red tomato) and interspecific grafts (Roma tomato grafted on Eggplant and Pepper plant) at 4, 8 and 16 DAG (days after grafting) to explore physiological, biochemical and metabolic changes at the graft junction that might be used as graft incompatibility markers. Results revealed that among grafted combinations intraspecific grafts depicted a vigorous resistance against oxidative damage by accumulating low hydrogen peroxide, minimum membrane permeability and lipid peroxidation coupled with high antioxidants activity compared to other grafted combinations while interspecific grafts with low survival rates showed high accumulation of total phenolic and flavonoid content at all three grafting stages (4, 8 and 16 DAG). During histological examinations of graft junctions, an apparent long adherence region at the graft junction of self-grafts and intraspecific grafts were observed while interspecific grafts present a small adhesion line. These variations at the structural, physiological and metabolic level may regulate incompatibility and may serve as markers for early detection of graft incompatibility. These findings may further help in the development of markers at molecular level valuable in rootstock development programs.