ISSN:
1432-2048
Keywords:
Abscisic acid
;
Cell cycle
;
DNA synthesis
;
Germination
;
Gibberellin
;
Lycopersicon
;
Seed
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The role of cis-abscisic acid (ABA) and gibberellins (GAs) in the induction of cell-cycle activities has been studied during imbibition and subsequent germination of tomato seeds. Using flow cytometry, nuclear replication activity was investigated in embryo root tips isolated from seeds of the ABA-deficient mutant sit w , the GA-deficient mutant gib-1, and the wild-type (MM) tomato (Lycopersicon esculentum Mill. cv. Moneymaker) upon imbibition in water, 10 μM GA4+7, 5 μM ABA or 5 μM ABA+10 μM GA4+7. The nuclei of fully matured dry MM, sit w and gib-1 seeds predominantly showed 2C DNA signals, indicating that the cell-cycle activity of most root-tip cells had been arrested at the G1 phase of nuclear division. However, ABA-deficient sit w seeds contained a significantly higher amount of G2 cells (4C DNA) compared with the other genotypes, suggesting that, during maturation, cell-cycle activity in sit w seeds is less efficiently arrested in G1. Upon imbibition in water, an induction of the 4C signal, indicating nuclear replication, was observed in the root tip cells of both MM and sit w embroys. The augmentation in the 4C signal occurred before visible germination. Gib-1 seeds did not show cell-cycle activity and did not germinate in water. Upon imbibition in GA4+7, both cell-cycle activity and subsequent germination were enhanced in MM and sit w seeds, and were induced in gib-1. In ABA, the germination of MM and sit w seeds was inhibited while nuclear replication of these seeds was not affected. It is concluded that GA influences germination by acting upon processes that precede cell-cycle activation, while ABA affects growth by acting upon processes that follow cell-cycle activation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00197537
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