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Osmotic potential and abscisic acid regulate triacylglycerol synthesis in developing wheat embryos

Rogelio Rodriguez-Sotres and Michael Black
Planta
Vol. 192, No. 1 (1994), pp. 9-15
Published by: Springer
Stable URL: http://www.jstor.org/stable/23382569
Page Count: 7
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Osmotic potential and abscisic acid regulate triacylglycerol synthesis in developing wheat embryos
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Abstract

This work was carried out to determine what factors in the developing wheat (Triticum aestivum L.) grain are involved in regulating the metabolism of the triacylglycerol (TAG) storage reserves. When embryos are isolated from the grain and incubated in media for 4 d the TAG content is affected in three ways. In the basal medium (dilute buffer) the content falls; in 30 mM sucrose the content remains unchanged; in sucrose supplemented with an osmoticum (400 mM mannitol) or abscisic acid (1 μM ABA) the TAG content increases. Effective osmotic potentials and ABA concentrations fit well with their respective values in planta. The fatty-acid composition of TAG accumulated in vitro is close to that in planta but in the absence of ABA or osmoticum there is a fall in the C18:C16 ratio. Experiments with [14C] acetate show that the in-planta rate of incorporation into TAG can only occur in isolated embryos treated osmotically or with ABA, while there seems to be no effect of these two factors on TAG breakdown. An osmotic 'shock' (dilute buffer) for only 2 h causes a rapid fall in TAG synthesis which continues for ca. 24 h after which it recovers. Abscisic acid protects against osmotic 'shock'. It is concluded that TAG synthesis in developing wheat embryos is regulated by the osmotic potential and-or ABA, and that the embryos are very sensitive to short-term perturbations of these two factors.

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