Mj. Hutchinson et al., DOES ETHYLENE PLAY A ROLE IN THIDIAZURON-REGULATED SOMATIC EMBRYOGENESIS OF GERANIUM (PELARGONIUM X HORTORUM BAILEY) HYPOCOTYL CULTURES, In vitro cellular & developmental biology. Plant, 33(2), 1997, pp. 136-141
The accumulation of ethylene in headspace of hypocotyl cultures of ger
anium (Pelargonium x hortorum Bailey) and its possible role in thidiaz
uron-mediated somatic embryogenesis was investigated. The action of et
hylene as determined by various ethylene synthesis and action inhibito
rs was varied. Silver nitrate (AgNo3), aminoethoxyvinylglycine (AVG),
and silver thiosulphate (STS) had no significant influence on the embr
yogenic response, while 1-methylcyclopropene (1-MCP) applied during th
e initial 3 d of induction or the expression phase, significantly incr
eased the number of somatic embryos formed. Thidiazuron-treated tissue
s accumulated large quantities of ethylene within 6 h of culture, but
the levels decreased after 12 h and reached very low levels after 3 d
in culture. In the presence of acetylsalicylic acid (ASA), the levels
of ethylene decreased by 20 to 50% during the first 48 h of culture. A
nalysis of endogenous auxin, cytokinins, and abscisic acid (ABA) indic
ated possible interactions of ethylene with other phytohormones during
the induction of somatic embryos on geranium hypocotyl explants. Thid
iazuron (10 mu M)) increased, while ASA decreased the levels of endoge
nous auxin, cytokinins, and abscisic acid during this period of induct
ion.