title: Efficient plant regeneration from long-term callus cultures of rice by spermidine.
abstract: A significant reduction in regeneration potential with increasing age (upto 12months) in rice (Oryza sativa L. cv.TN-1) embryogenic callus cultures was observed. Spermidine, while having an inhibitory effect on plant regeneration in fresh callus cultures, promoted morphogenesis in long-term callus cultures. A massive accumulation of polyamines, particularly putrescine (5-fold) was observed in 12 month old cultures resulting in a change of putrescine /spermidine ratio, which seems to be important for maintaining the morphogenetic response. Application of exogenous spermidine to 12 month old cultures showed increased levels of polyamines and restored the putrescine/spermidine ratio comparable to that found in freshly induced cultures, concomitantly, promoting the plant regeneration via somatic embryogenesis in long-term rice callus cultures.
authors.affiliation: Department of Genetics, University of Delhi, South Campus, Benito Juarez Road, -110021, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Bajaj
authors.forename: M V
authors.initials: MV
authors.lastname: Rajam