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Polyhydroxyalkanoate synthesis in transgenic plants as a new tool to study carbon flow through β‐oxidation
Author(s) -
Mittendorf Volker,
Bongcam Vanessa,
Allenbach Laure,
Coullerez Géraldine,
Martini Nobert,
Poirier Yves
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00572.x
Subject(s) - peroxisome , polyhydroxyalkanoates , biochemistry , chemistry , fatty acid , beta oxidation , monomer , organic chemistry , biology , gene , polymer , genetics , bacteria
Summary Transgenic plants producing peroxisomal polyhydroxy‐ alkanoate (PHA) from intermediates of fatty acid degradation were used to study carbon flow through the β‐oxidation cycle. Growth of transgenic plants in media containing fatty acids conjugated to Tween detergents resulted in an increased accumulation of PHA and incorporation into the polyester of monomers derived from the β‐oxidation of these fatty acids. Tween–laurate was a stronger inducer of β‐oxidation, as measured by acyl‐CoA oxidase activity, and a more potent modulator of PHA quantity and monomer composition than Tween–oleate. Plants co‐expressing a peroxisomal PHA synthase with a capryl‐acyl carrier protein thioesterase from Cuphea lanceolata produced eightfold more PHA compared to plants expressing only the PHA synthase. PHA produced in double transgenic plants contained mainly saturated monomers ranging from 6 to 10 carbons, indicating an enhanced flow of capric acid towards β‐oxidation. Together, these results support the hypothesis that plant cells have mechanisms which sense levels of free or esterified unusual fatty acids, resulting in changes in the activity of the β‐oxidation cycle as well as removal and degradation of these unusual fatty acids through β‐oxidation. Such enhanced flow of fatty acids through β‐oxidation can be utilized to modulate the amount and composition of PHA produced in transgenic plants. Furthermore, synthesis of PHAs in plants can be used as a new tool to study the quality and relative quantity of the carbon flow through β‐oxidation as well as to analyse the degradation pathway of unusual fatty acids.