Hormonal regulation of the postharvest anthocyanin biosynthesis in raspberries (Rubus idaeus)

Abstract

The color constitutes an important quality attribute for commercial fruits, being essential for the "small fruits" or "berries". In red raspberries (Rubus idaeus), the target of this project, the color of the ripe fruit is conferred by anthocyanins, which precursors are from phenylpropanoid pathway. The research about which factors regulate the anthocyanins synthesis in fruits has been concentrated in strawberries and grapes and has pointed out that ethylene, indol-3-acetic acid (IAA), abscisic acid (ABA) and methyl jasmonate (MJ) are implicated in the flavonoid accumulation or inhibition of their synthesis. However, the same cannot be postulated about other berries due to the lack of information about the regulatory factors involved in pigment synthesis during their ripening. In this context, the aim of this work is evaluate if the same hormonal factor has the same effects on anthocyanins synthesis in red raspberries. Fruits from Heritage cultivar will be treated with the hormones cited above and the effects on respiration, ethylene production, changes in color and the contents of soluble sugars, organic acids and anthocyanins will be analyzed. The contents of IAA, ABA and MJ will be also determined in fruits treated and non-treated (control) aiming to detect possible effects of each hormone on the level of another one and identify mechanisms of action. All hormonal alterations will be correlated to changes in composition in relation to the control with emphasis in anthocyanin biosynthesis. Additionally, the profile of transcripts of the dihydroflavonol reductase and anthocyanidin synthase, enzymes of the final steps of the anthocyanins synthesis, will be analyzed by qRT-PCR and correlated with the natural hormonal variation and the treatments. It is expected to identify which plant hormones are implicated in the pigments biosynthesis in red raspberries, providing the basis for possible interventions in the raspberry chain production of this fruit, aiming the increasing in its anthocyanin contents. The interest comes not only from the importance of these flavonoids to the sensorial quality of the red raspberries, but also to the improvement of their nutritional value, once that several reports have been demonstrated their potential in the prevention of non-transmissible chronic diseases. (AU)