作者机构：
CTR PLANT BREEDING & REPROD RES,DEPT REPROD TECHNOL,6700 AA WAGENINGEN,NETHERLANDS.;HUNAN AGR COLL,DEPT HORT,CHANGSHA 410128,PEOPLES R CHINA.;AGR UNIV WAGENINGEN,DEPT PLANT PHYSIOL,6703 BD WAGENINGEN,NETHERLANDS.;[LIU, YQ] Department of Horticulture, Hunan Agricultural College, Changsha, P.R. China;[BERGERVOET, JHW; DEVOS, CHR; KRAAK, HL; BINO, RJ] Department of Reproduction Technology, Centre for Plant Breeding and Reproduction Research (CPRO-DLO), Wageningen, The Netherlands
通讯机构：
Department of Reproduction Technology, Centre for Plant Breeding and Reproduction Research (CPRO-DLO), POB 16, Netherlands
摘要：
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 mu M GA(4+7), 5 mu M ABA or 5 mu M ABA + 10 mu M GA(4+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 G(1) phase of nuclear division. However, ABA-deficient sit(w) seeds contained a significantly higher amount of G(2) cells (4C DNA) compared with the other genotypes, suggesting that, during maturation, cell-cycle activity in sit(w) seeds is less efficiently arrested in G(1). 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 GA(4+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.
