PROLINE CYCLE AND ITS ROLE IN SECONDARY METABOLITE ACCUMULATION

PERASSOLO M; GIULIETTI AM; RODRÍGUEZ TALOU J

Proline: Biosynthesis, Regulation and Health Benefits

Nova Publishers

Año: 2013; p. 1 - 11

functions in plant cells. Accumulation of proline in response to different kinds of stress, such as drought, high salinity, UV irradiation and exposure to heavy metals is well documented. This amino acid has been described as exhibiting several functions in plant defense response, such as acting as a compatible osmolyte, having antioxidant properties and contributing to cell recovery after stress, among others. Besides its central role in defense response, the influence of proline in secondary metabolite accumulation has been a subject of research. Shetty and co-workers have proposed that the proline cycle could be coupled to the pentose phosphate pathway (PPP), an important metabolic route that generates erithrose-4-phosphate. The latter compound is the precursor of the shikimate pathway, whose end-product (chorismate) becomes the branch point between primary and secondary metabolism and can lead to the synthesis of important secondary metabolites. In the model proposed by Shetty, proline synthesis from glutamate generates two molecules of NADP+, which act as cofactors of the first two enzymes in the PPP. Stimulating the proline cycle of biosynthesis and degradation could induce the PPP and generate an excess of erythrose-4-phosphate, thereby, driving the carbon flux towards the shikimate pathway. In our work, we intend to review the effect of stimulating proline cycle on the accumulation of secondary metabolites, by the addition of proline analogs or precursors. Regarding this subject, we are going to discuss our findings related to anthraquinone production in Rubia tinctorum cell suspension cultures. Beside this, we will analyze the role of proline cycle in the defense response, focusing on its antioxidant activity and the effect on the final accumulation of secondary metabolites.