Fatty acid α-dioxygenase from Pisum sativum: Temporal and spatial regulation during germination and plant development

Summaryα-Dioxygenases are expressed in plants in response to biotic and abiotic stress. They catalyze the enantioselective 2-hydroperoxidation of long-chain fatty acids, the initial step of the α-oxidation pathway of fatty acids in plants. In this study, the complete cDNA of an α-dioxygenase from germinating pea seeds (Pisum sativum) is presented. The deduced amino acid sequence establishes that the enzyme belongs to the recently characterized family of α-dioxygenating enzymes in plants. We also present the first systematic study on the expression of α-dioxygenase in germinating and developing pea plants. During germination, α-dioxygenase mRNA accumulates in the cotyledons and the embryonic axis of pea seeds de novo. In developing pea plants, the transcript is detected almost exclusively in roots. The accumulation of α-dioxygenase protein parallels transcript accumulation in that it is abundant in germinating as well as young plant tissue, and correlates with loss of mRNA during plant maturation. α-Dioxygenase enzymatic activity in plant extracts is highest in cotyledons during imbibition. In the embryonic axis and roots of developing plants comparable activity levels are observed, whereas in shoots little α-oxidation activity is detected. With this contribution, we present information on the temporal and spatial expression of α-dioxygenase during plant germination and development, supporting the hypothesis that the α-oxidation pathway of fatty acids plays a role during plant developmental processes.