TOR-SnRK1 are modulated by upstream signaling to regulate growth and development in vitro of 'Myrobalan 29C' plum rootstock

- The aim of this study was: (i) understand how upstream signaling mod-ulated TOR-SnRK1 nexus; and (ii) establish an interplay between SnRK1-TOR nex-us, sugar availability, sucrolytic enzyme activities, expression level of key genes related to signalling and sugar metabolism, including trehalose, in in vitro-grown of 'Myrobalan 29C'plum rootstock (Prunus cerasifera). Explants were cultivated in Murashigue and Skoog medium (MS) with trehalose (0; 1,0 and 10 mM). In 3 days, the antagonistic role of PcSnRK1 and PcTOR was confirmed in plants treated with 10mM trehalose, possibly indicating that 'Myrobalan 29C' was not in a stress condi-tion. Furthermore, a PcTREA up-regulation was observed, which can lead to glucose accumulation, that in turn is precursor of sorbitol synthesis. Regarding the growth parameters evaluated after 21 days of in vitro culture, the uppermust number of shoots and explant length was observed at 10mM trehalose. Such positive response may be due to an increase in Glucose and UDP-Glc content, direct products of su-crose synthase (SuSy) enzyme. Consistent with these results, the highest availability of these molecules may be the upstream signal for TOR-activation. Interestingly, in this same condition, a sucrose accumulation was observed, which may also have contributed to PcTOR up-regulation and ameliorate in growth parameters.