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The zygotic embryogenesis and ripening of Brassica rapa seeds provokes important alterations in the levels of free and conjugated abscisic acid and polyamines
Author(s) -
PugaHermida María Isabel,
Gallardo Mercedes,
Matilla Angel Jesús
Publication year - 2003
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 - 10.1034/j.1399-3054.2003.00033.x
Subject(s) - silique , abscisic acid , brassica rapa , biology , botany , ripening , desiccation , brassica , polyamine , cotyledon , horticulture , arabidopsis thaliana , biochemistry , gene , mutant
Prior to the embryogenic study of Brassica rapa (turnip tops), the PA (polyamine) changes during flower development were determined. Whereas the flower was closed, no notable changes were found. However, pollination strongly stimulated the synthesis of the F (free) and ASC (acid soluble conjugated) forms, the pistil and not the petals being the main responsible. During embryogenesis, major alterations appeared in the synthesis of free and conjugated PA and ABA. Seeds, and not the silique wall, contributed most to the total content of the different F‐PA (free polyamines) in the silique, this contribution involving all the PA studied. During seed desiccation, F‐Put remained almost undetectable whereas F‐Spd and F‐Spm were very high. This is also applicable to ASC‐Spd and ASC‐Spm, this not being noted in the silique wall. During the first 5 stages of silique embryogenesis, the wall had higher levels of AIC‐PA (acid insoluble conjugated polyamines) than in the seeds, primarily due to AIC‐Spd and AIC‐Spm. By contrast, during the middle and final phases AIC‐PA was found more in the seeds than in the silique wall. The free and conjugated ABA showed the presence of 3 and 2 peaks in the seeds and the silique wall, respectively. The first corresponded to the onset of development, the second appeared when the highest moisture content was reached, and the third coincided with the triggering of carotenoid synthesis when the seed and the silique wall had lost more than 70–75% of their moisture. Finally, it is shown that the dry seeds of turnip tops were highly heterogeneous, not only in their germinative capacity, but also in the levels of free and conjugated ABA, which increased inversely to the germinative capacity.