Molecular studies of inheritable grafting induced changes in pepper (Capsicum annuum) fruit shape

Vegetable grafting is used extensively today by farmers primarily for facing soil borne problems – among other benefits – despite some unfavorable fruit quality effects observed in certain rootstock-scion combinations. Fruit shape is a characteristic known to be affected by grafting. Herein, working with pepper graftings between two pepper genotypes (cultivars) differing in fruit shape, we observed fruit shape changes after grafting the round shaped cultivar, cv. “Mytilini Round” (scion) on the long shaped cultivar, cv. “Piperaki Long” (rootstock). Furthermore, the phenotypic changes observed in scion fruits were inherited for two generations of seed derived progenies indicating that the changes imposed on scion are heritable. PCR amplifications using six inter simple sequence repeat (ISSR) primers showed that progenies developed from seeds collected from the modified scion fruits had a genetic profile more similar to the scion genetic profile and less similar to the rootstock profile indicating that only minor genetic changes occurred in the scion during grafting. The change in the fruit shape was not found to be accompanied by extended DNA sequence changes in pepper CaOvate sequence, a gene shown before to be involved in determining fruit shape in pepper, although a slight difference in CaOvate gene expression was found. Overall, understanding the molecular mechanisms that probably underline graft-induced changes paves the way to a better knowledge over the rootstock-scion interactions, the role of rootstock in scion performance and eventually the improved quality and fruit harvest from grafted vegetable plants.

► We conducted graftings between two pepper genotypes of different fruit shape.
► Graft induced changes in fruit shape were observed in the scion.
► The changes were inherited in the subsequent two seed progenies studied.
► Genetic profiling of progenies reveal minor genetic differences compared to scion.
► Particularly for CaOvate not extended sequence changes were recorded in progenies.