Harnessing Epigenetics through Grafting: Revolutionizing Horticultural Crop Production

Abstract

Grafting is an ancient agricultural technique that is frequently used to enhance the performance of horticultural plants, including vegetables and woody fruit trees. For successful grafting, genotypes of the compatible scion (the upper part) and the rootstock (the lower part) must interact. Molecular signals, including nutritional and hormonal signals, proteins, and messenger RNAs (mRNAs), are known to be transferred from the rootstock to the scion and vice versa. Nonetheless, there are still numerous mysteries regarding artificial grafts, including the occurrence of genetic/epigenetic alterations due to exchanges between the graft partners, and the long-term ramifications of these alterations on the phenotype are unknown. Recent studies on the interactions between rootstocks and scions suggest that grafting responses have an epigenetic component. In this review, we focus on the current knowledge of epigenetic consequences following grafting. Epigenetic regulations are known to regulate chromatin architecture, alter gene expression, and affect cellular function in plants. Mobile small RNAs, for example, have been shown to modify the DNA methylation pattern of the recipient partner across the graft union. More recently, mRNA 5-methylcytosine (m5C) modification has been shown to elucidate the long-distance transport mechanism of grafting in Arabidopsis thaliana. We also discuss how grafts can cause heritable epigenetic alterations that result in novel plant phenotypes, and how this might help increase horticultural crop quality, yield, and stress resistance in the context of climate change.