Characterization of Aldehyde Oxidase (AO) Genes Involved in the Accumulation of Carotenoid Pigments in Wheat Grain.

Pasqualina Colasuonno,Agata Gadaleta,Maria L Lozito,Rosanna Simeone,Ilaria Marcotuli,Antonio Blanco

doi:10.3389/fpls.2017.00863

Pasqualina Colasuonno, Agata Gadaleta + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2017.00863

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Abstract

Aldehyde Oxidase (AO) enzyme (EC 1.2.3.1) catalyzes the final steps of carotenoid catabolism and it is a key enzyme in the abscisic acid (ABA) biosynthesis. AO isoforms are located in the cytosolic compartment of tissues in many plants, where induce the oxidation of aldehydes into carboxylic acid, and in addition, catalyze the hydroxylation of some heterocycles. The goal of the present study was to characterize the AO genes involved in the accumulation of carotenoid pigments in wheat grain, an important quantitative trait controlled by multiple genes. The cDNAs corresponding to the four AO isoforms from Arabidopsis thaliana and five AO isoforms from Brachypodium distachyon were used as query in 454 sequence assemblies data for Triticum aestivum cv. Chinese Spring (https://urgi.versailles.inra.fr/blast/blast.php) to obtain the partial or whole orthologous wheat AO sequences. Three wheat isoforms, designated AO1, AO2, and AO3 were located on the chromosome groups 2, 5, and 7, respectively, and mapped on two consensus wheat maps by SNP markers located within the AO gene sequences. To validate the possible relationships between AO3 genes and carotenoid accumulation in wheat, the expression levels of AO-A3 and AO-B3 gene were determined during the kernel maturation stage of two durum wheat cultivars, Ciccio and Svevo, characterized by a low and high carotenoid content, respectively. Different AO-A3 gene expression values were observed between the two cultivars indicating that the AO-A3 allele present in Ciccio was more active in carotenoid degradation. A gene marker was developed and can be used for marker-assisted selection in wheat breeding programs.

Highlights

Yellow pigment concentration (YPC) in wheat is a quantitative trait controlled by a complex genetic system and influenced by environmental factors (Qin et al, 2016)
The cDNAs corresponding to the four Aldehyde Oxidase (AO) isoforms from A. thaliana (AT5G20960, AT3G43600, AT2G27150, and AT1G04580, designated, respectively O1, AO2, aldehyde oxidase 3 (AO3), and AO4) and the five AO isoforms from B. distachyon
The definitive assignment of AO sequences to the wheat A, B and D homoeologous chromosomes and the accurate map position was performed based on the best blastn hit with the available dataset of SNP marker sequences reported by Wang et al (2014) (Table 1)

Summary

Introduction

Yellow pigment concentration (YPC) in wheat is a quantitative trait controlled by a complex genetic system and influenced by environmental factors (Qin et al, 2016). Carotenoids are precursors of the vitamin A, with high nutritional relevance for human diet (Della Penna and Pogson, 2006; Britton, 2009), and substrates for the synthesis of apocarotenoids, compounds derived from oxidative cleavage and further modifications (Wurtzel et al, 2012). The first committed step of biosynthesis is mediated by the phytoene synthase (PSY) enzyme for the condensation of two molecules of geranylgeranyl diphosphate to produce phytoene. The phytoene goes through a series of desaturation reactions by phytoene desaturase (PDS), zeta-carotene isomerase (ZISO), zeta-carotene desaturase (ZDS), and carotenoid isomerase (CRTISO) enzymes, producing lycopene molecules. Double lycopene cyclization can produce precursor of lutein (branch βε) by lycopene ε-cyclase (LYCE) or β-carotene (branch β-β) by lycopene ß-cyclase (LYCB) (Qin et al, 2016)

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