Post-pollination biochemical changes in the floral organs ofRhynchostylis retusa (L.) Bl. andAerides multiflora Roxb. (Orchidaceae)

Role of Auxin in Orchid Development

“…34 Following pollination, an increase in hydrolytic activity produced soluble sugars, amino acids, and phosphorus in senescing petals and sepals. 35,36 Inhibitors of auxin and ethylene partially prevented the activity of these enzymes during the death process. 35 Auxin also appears to play a role in floral bud initiation, but reports of its action are not entirely consistent between studies conducted with different orchid species ( Table 1).…”

“…35,36 Inhibitors of auxin and ethylene partially prevented the activity of these enzymes during the death process. 35 Auxin also appears to play a role in floral bud initiation, but reports of its action are not entirely consistent between studies conducted with different orchid species ( Table 1). The cytokinin, benzyladenine (BA), promoted inflorescence initiation in select orchid species, 37,38 however in Dendrobium, IAA countered the inductive effect of BA on flowering.…”

Post-pollination changes in the floral organs of two Cymbidium species

“…Likewise, Paphiopedilum blossoms lasted for 3 months in unpollinated state but senesced within 3 weeks after pollination (Arditti 1992). Similarly, the flowers of Aerides multiflora and Rhynchostylis retusa stays fresh for 17 and 24 d, respectively, but perished within 5 and 7 d after pollination (Attri et al 2007). In the present study also, the unpollinated flowers of Cymbidium pendulum stayed fresh for 20 d and attained senescence in 6 -7 d after pollination (DAP), while those of Cymbidium aloifolium remained fresh for 18 d without pollination and senesced in 8 DAP.…”

“…It has been reported that pollen interaction with stigma either releases auxin that stimulates ethylene synthesis or 1-aminocyclopropane-1-carboxylic acid (ACC) a precursor of ethylene (O'Neill et al 1993), which traverses across the flower organs leading to onset of their senescence by affecting metabolic events (Bui and O'Neill 1998). Various developmental events occurring after pollination are also reported to be influenced by auxin or ethylene (Van Doorn 1997, Attri et al 2007). Information about the precise metabolic alterations in relation to involvement of these hormones is lacking.…”

“…Auxins and ethylene have been implicated in controlling the pollination-induced response in flowers (Ketsa et al 2006, Attri et al 2007). It has been reported that pollen interaction with stigma either releases auxin that stimulates ethylene synthesis or 1-aminocyclopropane-1-carboxylic acid (ACC) a precursor of ethylene (O'Neill et al 1993), which traverses across the flower organs leading to onset of their senescence by affecting metabolic events (Bui and O'Neill 1998).…”