Different regulation of target genes coding components of phenolics compounds biosynthesis pathways and their accumulations in apple and olive mutants
Author(s)
Cirilli, Marco
Date Issued
May 30, 2014
Type
Doctoral Thesis
Abstract
The growing interest from nutritionist and consumers for food phytochemicals has opened new
challenges for agriculture and food industries, particularly towards functional foods. Spontaneous mutants of
cultivated species characterized by high phytochemicals content represent important resources both for
scientific and productive purpose. In these researches, spontaneous mutants of apple and olive species have
been investigate to evaluate their use as functional food or as scientific tools for the comprehension of
biochemical and molecular mechanism, which regulate polyphenol biosynthesis and accumulation. The
apples of Italian Red Passion (IRP) group, having red to pink coloration of flesh tissues, have been
investigated, with particular attention to their nutraceutical value, their sensorial attributes and consumer’s
preferences. IRP apples group are characterized by higher polyphenols content compared to commercial
apple such as Annurca. The higher polyphenols content of IRP flesh is due to a general increase in
qualitative and quantitative content of many polyphenols classes, including chlorogenic acids, flavan-3-ols,
dihydrochalcones and anthocyanins. The high polyphenol content did not affect the sensorial attributes of
IRP apples and the analysis of consumers’ preferences for red-flesh apples highlight the propensity of
consumers to taste and purchase the new apple product, mainly guided by their high nutraceutical values.
From scientific viewpoint, IRP apple lines represent an important tools for the comprehension of genetic and
biochemical mechanism regulating phenolics compounds accumulation in apple fruit. Molecular analysis
confirm the belonging of IRP lines to type I red-flesh apple group, characterized by the minisatellites
insertion in MdMYB10 promoter region, which confer trans-activation of MYB10 itself. However, as
demonstrated by in dept transcriptional analysis, the presence of mutated MYB10 alone is not able to explain
the different apple phenotypes regarding red pigmentation. The different expression of other upstream
regulator of flavonoid pathway, such as MdbHLH3/33 genes between IRP apples might indicate a functional
diversity not directly associated with MYB mutation. Some evidences have been found about the role of
epigenetic regulators, such as mdo-miR858, in the regulation of MYB genes regulating specific branches of
flavonoid pathways. The mutant’s cv Leucocarpa is characterized by the colorless phenotype of mature
drupe. This feature make this cultivar an excellent tool to investigate genetic mechanism, which regulate
flavonoid biosynthesis in drupe. Molecular and metabolic analysis have demonstrated that anthocyanins
biosynthesis in olive is regulated by a specific subset of structural genes (OeDFR and OeANS) temporally
regulated during olive drupe development and ripening. In addition, the potential use of NIR spectroscopy to
measure olive firmness and pigments content has been evaluated, obtaining promising results. Finally,
preliminary studies have been reported about the abundance of plant small-RNA that might have the putative
ability to regulate human health, in olive and apple fruit and some derived products. The integration of food
technology with recent advances in human nutrition may help to expand the concept of fruit quality to
include other molecules, such as specific classes of small-RNA, characterized by a potential benefit for
human health.
Additional information
Dottorato di ricerca in Biotecnologia degli alimenti
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