Polyamine metabolism, floral initiation and floral development in Chrysanthemum (Chrysanthemum morifolium Ramat.)

Abstract

In the short-day plant Chrysanthemum (Chrysanthemum morifolium Ramat. variety Pavo) putrescine and spermidine conjugates appeared in the apical bud before the first observable transformation of the meristem into floral structures . These compounds accumulated on floral initiation and well before floral evocation . Spermidine conjugates were predominant during floral initiation whereas free amines did not accumulate to any significant extent . Different associations of amides were observed during floral initiation as compared with the reproductive phase . 3,4-Dimethoxyphenethylamine conjugates (water-insoluble compounds) were the predominant amine conjugates observed during flower development . These compounds decreased drastically after fertilization . In vegetative buds from plants grown in long days polyamine conjugates were very low and appeared as plants aged . We present evidence that omithine decarboxylase (ODC) regulates putrescine biosynthesis during floral initiation and floral development . When ODC action was blocked by DFMO (a-DL-difluoromethylornithine, a specific, irreversible inhibitor of ODC), flowering was inhibited, and free and conjugated polyamines were not detected . This treatment led to a slight enhancement of ADC activity . When putrescine was added, polyamine titers and flowering were restored . A similar treatment with DFMA (a-DL difluoromethylarginine, a specific, irreversible inhibitor of ADC) did not affect flowering and the polyamine titers . The results suggest that ODC and polyamine conjugates are involved in regulating floral initiation in Chrysanthemum .Abbreviations : ADC = arginine decarboxylase ; ODC = ornithine decarboxylase ; DFMA = a-DLdifluoromethylarginine ; DFMO = a-DL-difluoromethylomithine .

Relationship between Endogenous Polyamines and Floral Bud Differentiation in Chrysanthemum morifolium under Short-day Conditions

“…In this study, the rapid increase in the free-Put pool in apical buds during stage 2 illustrated its importance to initiation of floral bud formation. This result was contrary to the findings of Aribaud and Martin-Tanguy (1994), possibly because of differences in the study species, temperature, or other factors. However, the content of Put remained low (even lower than that at stage 1) from the differentiation of the involucre primordia until crown formation.…”

“…The importance of polyamines in flower bud differentiation has been confirmed by numerous laboratory studies (Aribaud and Martin-Tanguy, 1994;Huang et al, 2004;Meijón et al, 2011;Wimalasekera et al, 2011). Endogenous PA concentrations in plants change dramatically during the transition from vegetative phase to reproductive (Applewhite et al, 2000;Aribaud and Martin-Tanguy, 1994;Davis, 2009;Meijón et al, 2011;Wimalasekera et al, 2011). Conjugated PAs have been shown to play a key role in floral development (Martin-Tanguy, 1997) and be of particular significance for regulation of PA concentration (Bagni and Tassoni, 2001).…”

“…PAs play important roles in plants, such as promoting plant growth, inhibiting the activity of protease and RNA enzymes and increasing plant resistance and so on. And they also play important roles in floral bud differentiation (Aribaud and Martin-Tanguy, 1994) and pollen formation (Wimalasekera et al, 2011) in horticultural crops.…”

“…The floral bud differentiation of chrysanthemum associated with endogenous hormones (Feng and Yang, 2011), endogenous PAs (Aribaud and Martin-Tanguy, 1994), environmental factors (Yang et al, 2006), carbohydrates (Lang et al, 2008) and so on. Regarding the role of polyamines in flowering of chrysanthemum, Aribaud and Martin-Tanguy (1994) described changes in PAs in apical buds and proposed that some polyamines may be involved in regulating floral initiation. Since that report, the function of PAs metabolism in chrysanthemum remained an outstanding question.…”

Polyamines are involved in the gynogenesis process in onion

“…This pattern has even been associated with good development of gametic embryos through our observations. In various species, high concentration of endogenous Spd has been associated with floral induction and development (Aribaud and Martin-Tanguy 1994a, Kaur-Sawhney et al 1988, Tiburcio et al 1990) and mentioned in studies on embryogenic tissues (Cvikrova et al 1999, Minocha et al 1999. Levels of OHPut in embryogenic tissues have not been reported in the literature, although its absence was a clear marker for gynogenesis capacity in onion (Table 1).…”