Selenium nanoparticles promote adventitious rooting without callus formation at the base of passion fruit cuttings via hormonal homeostasis changes

•SeNPs promoted adventitious root AR formation without callusing, and callus is not necessary for adventitious root formation.•SeNPs directed AR formation rather than callusing by decreasing the CKs/ABA ratio and stimulating the simultaneous increased of IAA, Kin, zeatin, GA3 and ABA, GA3/IAA, GA3/CKs, GA3/ABA during the induction phase of AR founder cells.•Callus formation from cortex cell precursors was a mechanical barrier to AR formation from vascular cambium cells.•High 2ip, IAA/CKs, IAA/ABA and low GA3/IAA showed a prominent role in callus formation at cuttings induced by IBA.•The presence of callus negatively affected the survival and growth of passion fruit cuttings during the acclimatization period. Callus formation at the cutting base is an interesting and common phenomenon in cuttings; however, little is known of histology and hormonal dynamics during the adventitious root formation (AR) and callusing stages of cuttings, also the relationship between them, were the aims of this study. The results showed that all SeNPs selenium nanoparticles (SeNPs) concentrations (1.0; 3.0; 5.0; 7.0 and 9.0 mg/L) and control (-) which is AR stimulants-free showed an impact AR formation without callusing in passion fruit cuttings. Meanwhile, regardless of the callus accumulation induced by cortex cell proliferation at cutting base that promoted by 2.5 mg/L IBA-control (+), no ARs differentiated from callus but rather from vascular cambium cells. It implies callus formation is not an obligatory trigger/signal for AR formation. Interestingly, SeNPs regulate IAA, Kin, zeatin, GA3 and ABA levels that peak during the S1 phase (S1-induction root/callus founder cells) consequent an increase in GA3/IAA, GA3/CKs, GA3/ABA ratios and a decrease in CKs/ABA ratio causing early vascular differentiation and of cambial derivatives behavioral modification, when crosstalk further regulates responses during AR-forming cellular reprogramming. On the other hand, callus induced by IBA impeded AR formation and growth traits due to increased endogenous 2ip, IAA/CKs and decreased GA3/IAA ratio during S1. Furthermore, the sustained high maintenance IAA/CKs and IAA/ABA ratios during S1-S3 (S3-massive rooting phase) favor callusing. SeNPs derived-plantlets without accumulate callus exhibited higher survival rate and superior growth during acclimatization stage compared with those controls, emphasizing that callusing was detrimental to passion fruit cuttings.