Jasmonic acid metabolism and signalling are repressed in NCED OE rootstocks
As in own-rooted plants (Martínez-Andújar et al. 2020b), NCED OE rootstocks downregulated the JA biosynthetic (JA1 , Solyc05g007180; LOX, Solyc03g096460), JA conjugation (MEJ s, Solyc03g044820 and Solyc03g070380) and signalling (JAZ, Solyc06g068930 ) genes, to a greater extent in SP5 than SP12. Interestingly, the ABA-activated NAC transcription factorJA2 , which promotes stomatal closure by inducing expression of the ABA biosynthetic gene NCED1 and acts as a regulatory loop to monitor endogenous ABA status (Muñoz-Espinoza, López-Climent, Casaretto & Gómez-Cadenas 2015), was induced in SP12, but inhibited in SP5 rootstocks (RT-qPCR data, Figure 7c). Despite this negative JA-ABA interaction, transient foliar JA accumulation (1.3 fold higher at 80 DST, Table S1) was concurrent with reduced ABA accumulation in scions grafted on NCED OE rootstocks.