title: Control of in vitro rooting and plant development in Corymbia maculata by silver nitrate, silver thiosulfate and thiosulfate ion.
abstract: Plant regeneration and transformation in vitro is often improved by adding silver ion (Ag(+)) to the culture media as AgNO(3) or silver thiosulfate (STS). Ag(+) reacts with substances to form insoluble precipitates, while thiosulfate (S(2)O(3) (2-)) interferes with these reactions. We studied the implications of silver precipitation and S(2)O(3) (2-) in the medium for culture development by (1) examining formation of Ag(+) precipitates from AgNO(3) versus STS in agar gels and their possible dependence on agar type; (2) comparing Corymbia maculata culture responses to AgNO(3) and STS and determining which better suits control of culture development; (3) clarifying whether STS-dependent alterations in culture development are due to Ag(+) alone or also to a separate influence of S(2)O(3) (2-). Silver precipitates appeared in aqueous gels of four agar brands supplemented with AgNO(3), but not in Phytagel(™), which remained transparent. No precipitation was observed in gels with STS. Indole-3-butyric acid (IBA)-mediated adventitious root induction and shoot growth were higher in C. maculata shoot tips cultured on gels with STS versus AgNO(3) (6-25 μM Ag(+)). IBA-treated shoot tips exhibited enhanced adventitious root regeneration, accelerated root elongation, increased frequency of lateral root formation, and stimulated shoot growth mediated by 100-250 μM sodium thiosulfate (Na(2)S(2)O(3)) in medium without Ag(+). The potency of S(2)O(3) (2-) in facilitating culture development has never been recognized. It is inferred that superiority of STS in stimulating multiple responses of C. maculata culture results from sustained biological activity of Ag(+) through prevention of its precipitation, and from impact of S(2)O(3) (2-) on cell differentiation and growth.
authors.affiliation: Department of Vegetable Research, Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, 50250, Bet Dagan, Israel. steinitz@volcani.agri.gov.il
authors.forename: Benjamin
authors.initials: B
authors.lastname: Steinitz
authors.forename: Nurit
authors.initials: N
authors.lastname: Barr
authors.forename: Yona
authors.initials: Y
authors.lastname: Tabib
authors.forename: Yiftach
authors.initials: Y
authors.lastname: Vaknin
authors.forename: Nirit
authors.initials: N
authors.lastname: Bernstein
mesh_terms: D000362:Agar; D002712:Chlorides / Q000032:analysis; D003470:Culture Media; D027822:Myrtaceae / Q000187:drug effects / Q000254:growth & development*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D012835:Silver Nitrate / Q000494:pharmacology*; D013885:Thiosulfates / Q000494:pharmacology*; D046509:Tissue Culture Techniques
chemical_list: D002712:Chlorides; D003470:Culture Media; D013885:Thiosulfates; C095213:silver thiosulfate; D000362:Agar; D012835:Silver Nitrate