Oligosaccharide inhibits ethylene synthesis and stimulates somatic embryogenesis in a cotton cell culture

The effect of a three-component oligosaccharide fragment of xyloglucan FucG alXyl (XG3) on callus-tissue growth and somatic embryogenesis was investiga ted in a cotton (Gossypium hirsutum L.) cell suspension culture. The oligos accharide introduced into an induction medium at 10(-8) and 10(-7) M concen trations did not affect the frequency of callus formation from hypocotyl se gments; however, it enhanced the monthly increment of callus-tissue weight 1.5- and 3-fold, respectively. Induction and culturing of the callus on an XG3-containing medium adversely affected its morphogenetic potential. Addit ion of XG3 to the culture medium during the cell suspension preparation sti mulated cell division resulting, after 40 days, in a 3.4-fold (at 10(-8) M XG3) and a 1.7-fold (at 10(-7) M XG3) increase in the cell number as compar ed to the control. Exclusion of 2,4-D, kinetin, and oligosaccharide from th e culture medium caused, after two weeks, a 3.8-fold increase in the number of embryos in the 10(-7) M XG3-treated suspension culture as compared to t he control. The stimulation of somatic embryogenesis by the oligosaccharide was accompanied by a 12-fold decrease in ethylene emission. The morphogene tic effect of oligosaccharide is suggested to result from its anti-auxin ac tion, which, in particular, inhibited the auxin-dependent ethylene synthesi s.