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.