Effects of osmotic preconditioning on nuclear replication activity in seeds of pepper (Capsicum annuum)

Abstract

Effects of osmotic preconditioning on nuclear replication activity in seeds of pepper {Capsicum annuum). -Physiol. Plant. 89: 433-440.Flow cytometric determination of nuclear DNA contents in embryos of dry, fully matured pepper seeds revealed only 2C signals. Therefore, pepper belongs to those species in which the quiescent embryo arrests nuclear division in the presynthetic G, phase. In whole seeds, two other peaks were observed which corresponded with the 3C and 6C DNA content and originated from the triploid endosperm. After 36 to 48 h of imbibition in water (48 to 60 h before visible germination), a rise in the 4C signal was observed in the root tip of the embryo. Osmotic preconditioning (priming) of pepper seeds for 7, 14 or 21 days in polyethylene glycol (PEG) or KNO3 + K3PO4 considerably reduced the time to 50% germination (t^,,) and the mean germination time, and the effect was proportional to the duration of the priming treatments. An induction of the 4C signal was firstly observed after 10 days osmopriming in either PEG or KNO3 + K3PO4. For both priming methods, a positive correlation was found between the efficiency of the treatment to reduce the mean germination time, and the induction of DNA synthesis, measured as the amount of 4C versus 2C, at 12 h before radicle protrusion. Apart from the quantitative effect, there was also a temporal influence of priming on DNA synthetic activity. When primed seeds were subsequently imbibed in water,'the induction of DNA synthesis started about 12 h earlier than in untreated seeds. This was also found for seeds primed for 7 days, when no induction of DNA synthesis had yet occurred. Apparently, during priming of pepper seeds there is a lag period of 9 days in which physiological processes other than DNA synthesis can take place. These processes sustain a rapid inception of nuclear replicative activity upon imbibition. By comparing the relative nuclear DNA contents of dry, imbibed and primed seeds, we provide information about the relation between the percentage of cells in seeds which have entered the replication stage of nuclear division, and germination performance. >>

Priming and re-drying improve the survival of mature seeds of Digitalis purpurea during storage

“…Rao et al, 1987). There are many examples of priming increasing the rate of germination Lanteri et al, 1993;Sarocco et al, 1995;Powell et al, 2000), and some of increases in ability to germinate (Georghiou et al, 1987;Demir, 2003). However, when combined with subsequent desiccation, the effect of priming is not consistently positive.…”

“…Priming has been shown to be both beneficial (Georghiou et al, 1987;Probert et al, 1991;Wechsberg, 1994) and detrimental Tarquis and Bradford, 1992) to subsequent longevity. Increases in the rate of germination through priming have been attributed to the advancement of germination metabolism (Lanteri et al, 1993;Sarocco et al, 1995;Soeda et al, 2005), enhanced antioxidant activity (Bailly et al, 2000) and, particularly where longevity is improved, repair processes (Burgass and Powell, 1984;Ashraf and Bray, 1993;Bray et al, 1993;Sivritepe and Dourado, 1995). Negative effects of priming have been explained as the consequence of germination sensu strictu having advanced to a state where seeds have lost desiccation tolerance (Ś liwińska and Jendrzejczak, 2002) or are less able to resist damage during air-dry storage (Powell et al, 2000).…”

[beta]-Tubulin Accumulation and DNA Replication in Imbibing Tomato Seeds

“…and pepper (Capsicurn annuum L.), imbibition is coupled to initiation of DNA replication in cells of the embryo root tip, as was demonstrated by flow cytometric analysis of isolated nuclei (Bino et al, 1992;Lanteri et al, 1993). In these species, the embryonic cells progress through the S phase of the cell cycle into the G, phase before visible germination.…”

Presença de nematoides em plantas de soja: relação com a ocorrência de sementes esverdeadas e seu potencial fisiológico

“…A cultivar foi considerado suscetível quando o fator de reprodução foi superior a 1, ou seja, quando foi verificado a multiplicação do nematoide. As amostras de núcleos para a análise por meio da citometria de fluxo foram preparadas de acordo com o procedimento proposto por Lanteri et al (1993). Para isso, foram utilizadas 10 sementes secas e embebidas por 24 horas para cada tratamento e estas foram dissecadas em eixo embrionário e cotilédones para avaliação separada de cada parte da semente.…”