Abstract
Accumulated in large amounts in carrot, carotenoids are an important product quality attribute and therefore a major breeding trait. However, the knowledge of carotenoid accumulation genetic control in this root vegetable is still limited. In order to identify the genetic variants linked to this character, we performed an association mapping study with a candidate gene approach. We developed an original unstructured population with a broad genetic basis to avoid the pitfall of false positive detection due to population stratification. We genotyped 109 SNPs located in 17 candidate genes – mostly carotenoid biosynthesis genes – on 380 individuals, and tested the association with carotenoid contents and color components. Total carotenoids and β-carotene contents were significantly associated with genes zeaxanthin epoxydase (ZEP), phytoene desaturase (PDS) and carotenoid isomerase (CRTISO) while α-carotene was associated with CRTISO and plastid terminal oxidase (PTOX) genes. Color components were associated most significantly with ZEP. Our results suggest the involvement of the couple PDS/PTOX and ZEP in carotenoid accumulation, as the result of the metabolic and catabolic activities respectively. This study brings new insights in the understanding of the carotenoid pathway in non-photosynthetic organs.
Highlights
Carotenoid compounds play an essential role in human health, preventing disease thanks to their antioxidant capacity, and as provitamin A precursors
As all individuals descended from the same parents, relatedness estimated with kinship matrixes had to be included in the association model
We identified several SNPs and genes associated with carotenoid content and color components
Summary
Carotenoid compounds play an essential role in human health, preventing disease thanks to their antioxidant capacity, and as provitamin A precursors. Carrot is one of the most important vegetables in the world, and a critical source of carotenoid as a large amount is accumulated in root tissues [2]. Genetic resources exhibit a large range of colors and PLOS ONE | DOI:10.1371/journal.pone.0116674. Carotenoid Content and Root Color of Cultivated Carrot carotenoid content patterns [3], questioning the genetic control of carotenoid accumulation in carrot. Multiple steps in the pathway have been identified as controlling the carotenoid diversity and amount in various plant organs. Accumulation of phytoene, controlled by the phytoene synthase and the phytoene desaturase, has emerged as a key regulatory step in the accumulation of carotenoids in various storage organs [9,10,11,12,13]
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