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Determination of floral organ type in cultured Silene shoot apices
Author(s) -
Donnison Iain Simon,
Francis Dennis
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb00160.x
Subject(s) - whorl (mollusc) , sepal , petal , biology , stamen , gynoecium , caryophyllaceae , botany , pollen , genus
Shoot apices of the long day plant, Silene coeli‐rosa , were cultured on a basal medium (+3% sucrose) in non‐inductive short days (SD) following their excision from plants which had been exposed to long day (LD) treatments in order to examine the period for determination of each floral whorl. In response to the inductive LD treatments, the pattern of whorl formation in vitro reflected their normal appearance in Silene : sepals, stamens 1–5, petals, stamens 6–10 and carpels, although the number of apices initiating each whorl was lower in vitro compared with apices in vivo. However, supplementing the medium with 7 instead of 3% sucrose corrected this deficiency and, for the first time, resulted in apices initiating floral whorls in SD. The interval between the shortest treatment to result in whorl initiation in vitro, 4 LD (which also resulted in 50% flowering in vivo), and the treatment which gave 50% initiation of the corresponding whorl in vitro, was taken to be the period for determination of that whorl. The determination times on the 3% medium were: sepals (2 days), stamens 1–5 (3 days), petals (3 days), stamens 6–10 (4 days) and carpels (4 days); all of these periods shortened to about 1 day on the 7% medium. Tissue culture did not perturb the pattern of initiation of each whorl since apices excised and cultured from plants which had received 7 LD + 2 SD, exhibited each whorl over the same time scale as those of intact plants which received the same treatment. The data are consistent with a sequential determination and initiation of each whorl in the order that they appear normally in Silene . Synchronisation of cell division, as represented by peaks of the mitotic index and G 2 /G 1 ratios on day 8 (7 LD + 2 SD), did not occur in vitro but the mitotic index did not descend to zero, further emphasising that tissue culture did not perturb the Silene apex.