Objective The research aimed to study the affinity performance of solanaceous crops grafting, and explore the physiological and biochemical reactions at the interface of tomato scion grafted on different rootstocks.

Method By setting tomato scion self-grafting (TS/TS) as the control, and comparing with tomato scion grafting tomato rootstock (TS/TR), tomato scion grafting eggplant rootstock (TS/ER), tomato scion grafting pepper rootstock (TS/PR), the activities of polyphenol oxidase (PPO), peroxidase (POD) and superoxide dismutase (SOD) at different time points after grafting of different grafting combinations were systematically evaluated. The contents of total phenols, total flavonoids, malondialdehyde (MDA), auxin (IAA), cytokinin (CTK), gibberellin (GA), abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) were determined.

Result It was found that TS/TS, TS/TR and TS/ER had good affinity, while TS/PR had poor affinity. After 24 days of grafting, the total phenols, total flavonoids and MDA contents of TS/PR were 2.26 mg/g, 1.88 mg/g and 6.51 μmol/L, respectively, while those of TS/TS were 0.65 mg/g, 0.26 mg/g and 2.66 μmol/L, respectively. The contents of total phenols, total flavonoids and MDA at the interface of TS/TR and TS/ER with good self-grafting and affinity were significantly lower than those of TS/PR, the degree of oxidative stress at the interface was less. The total phenols, total flavonoids and MDA contents at the interface of TS/TR and TS/ER wer significantly higher than those of TS/TS at the growth stage. PCA analysis of enzyme activity and related substance content at the interface showed that there were significant differences in interface oxidation related indexes between the same grafting and the different grafting. The determination of six hormones at the interface of different grafting combinations showed that CTK content was the lowest and JA content was the highest at the self-grafting interface, while CTK content was the highest and JA content was the lowest at the TS/PR combination interface. The correlation analysis of 6 hormones showed that JA and SA contents were significantly positively correlated at the interface of different grafting combinations, and CTK was significantly positively correlated with ABA. CTK was significantly negatively correlated with JA, ABA was significantly negatively correlated with JA, and SA was significantly negatively correlated with CTK.

Conclusion The physiological and biochemical state at the interface of tomato grafted seedlings is related to grafting affinity. The higher the affinity of rootstock and scion, the lower the degree of oxidative stress at the interface. The worse the affinity, the higher the degree of oxidative stress. Grafting affinity is not only reflected in the normal growth after grafting, but also in the symbiotic process after grafting between rootstock and scion. The hormone content s at the interface of grafting is related to the affinity of rootstock and scion. The contents of JA and SA at the interface of compatible grafting combination are higher, and the contents of ABA and CTK in incompatible grafting combinations are higher.