Biology subjects

Schwab, W.

Publications and source records attributed to Schwab, W..

3 recordsLinked to original sources

bioRxiv2020

Glycosylation of bioactive C13-apocarotenols in Nicotiana benthamiana and Mentha x piperita

C13-apocarotenoids (norisoprenoids) are carotenoid-derived oxidation products, which perform important physiological functions in plants. Although their biosynthetic pathways have been extensively studied, their metabolism including glycosylation remains elusive. Candidate uridine-diphosphate glycosyltransferase genes (UGTs) were selected for their high transcript abundance in comparison with other UGTs in vegetative tissues of Nicotiana benthamiana and Mentha x piperita, as these tissues are rich sources of apocarotenoid glucosides. Hydroxylated C13-apocarotenol substrates were produced by P450-catalyzed biotransformation and microbial/plant enzyme systems were established for the synthesis of glycosides. Natural substrates were identified by physiological aglycone libraries prepared from isolated plant glycosides. In total, we identified six UGTs that catalyze the unprecedented glucosylation of C13-apocarotenols, where glucose is bound either to the cyclohexene ring or butane side chain. MpUGT86C10 is a superior novel enzyme that catalyzes the glucosylation of allelopathic 3-hydroxy--damascone, 3-oxo--ionol, 3-oxo-7,8-dihydro--ionol (Blumenol C) and 3-hydroxy-7,8-dihydro-{beta}-ionol, while a germination test demonstrated the higher phytotoxic potential of a norisoprenoid glucoside in comparison to its aglycone. Glycosylation of C13-apocarotenoids has several functions in plants, including increased allelopathic activity of the aglycone, facilitating exudation by roots and allowing symbiosis with arbuscular mycorrhizal fungi. The results enable in-depth analyses of the roles of glycosylated norisoprenoid allelochemicals, the physiological functions of apocarotenoids during arbuscular mycorrhizal colonization and the associated maintenance of carotenoid homeostasis. One-sentence summaryWe identified six transferases in Nicotiana benthamiana and Mentha x piperita, two rich sources of glycosylated apocarotenoids that catalyze the unprecedented glycosylation of a range of hydroxylated - and {beta}-ionone/ionol derivatives and were able to modify bioactivity by glucosylation.

biochemistry↗

bioRxiv2020

The genetic architecture of fruit colour in strawberry (Fragaria x ananassa) uncovers the predominant contribution of the F. vesca subgenome to anthocyanins and reveals underlying genetic variations

Fruit colour, which is central to the sensorial and nutritional quality of the fruit, is a major breeding target in cultivated strawberry (Fragaria x ananassa). Red fruit colour is caused by the accumulation of anthocyanins, which are water-soluble flavonoids. Here, using pseudo F1 progeny derived from the cv. Capitola and the advanced line CF1116 and taking advantage of the available high density SNP array, we delineated fruit flavonoids mQTLs (13 compounds: anthocyanin, flavonols and flavan-3-ols) and colour-related QTLs (total anthocyanins and fruit colour) to narrow genomic regions corresponding to specific subgenomes of the cultivated strawberry. Findings showed that the overwhelming majority of the anthocyanin mQTLs and other colour-related QTLs are specific to F. vesca subgenome but that other subgenomes also contribute to colour variations. We then focused on two major homoeo-mQTLs for pelargonidin-3-glucoside (PgGs) localized on both male and female maps on linkage group LG3a (F. vesca subgenome). Combined high-resolution mapping of PgGs mQTLs and colour QTLs, transcriptome analysis of selected progeny individuals and whole genome sequencing of the parents led to the identification of several INDELS in the cis-regulatory region of a MYB102-like ODORANT gene and of the deletion of a putative MADS box binding motif in the 5UTR upstream region of an anthocyanidin reductase (ANR) gene, which likely underlie significant colour variations in strawberry fruit. The implications of these findings are important for the functional analysis and genetic engineering of colour-related genes and for the breeding by Marker-Assisted-Selection of new strawberry varieties with improved colour and health-benefits.

genetics↗

bioRxiv2020

Metabolite Quantitative Trait Loci for flavonoids provide new insights into the genetic architecture of strawberry (Fragaria x ananassa) fruit quality

Flavonoids are products from specialized metabolism that contribute to fruit sensorial (colour) and nutritional (antioxidant properties) quality. Here, using a pseudo full-sibling F1 progeny previously studied for fruit sensorial quality of cultivated strawberry (Fragaria x ananassa), we explored over two successive years the genetic architecture of flavonoid-related traits using LC-ESI-MS (13 compounds including anthocyanins, flavonols and flavan-3-ols) and colorimetric assays (anthocyanins, flavonoids, phenolics, FRAP and TEAC antioxidant capacity). Network correlation analysis highlighted the high connectivity of flavonoid compounds within each chemical class and low correlation with colorimetric traits except anthocyanins. Mapping onto the female and male linkage maps of 152 flavonoid metabolic QTLs (mQTLs) and of 26 colorimetric QTLs indicated co-localization on few linkage groups of major flavonoid- and taste-related QTLs previously uncovered. These results pave the way for the discovery of genetic variations underlying flavonoid mQTLs and for marker-assisted selection of strawberry varieties with improved sensorial and nutritional quality.

genetics↗