Structural Gene Expression in Carotenoid Biosynthetic Pathway of Carrot during Root Development
Conference Paper
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
Carrot root colors are mainly attributed to composition and content of carotenoids, which are health beneficial bioactive compounds for human health. Carotenoid biosynthesis mechanism as well as root color inheritance is very complex in carrot, as compared to other crops. This study was conducted to examine if differential carotenoid accumulation in various colored roots was related to mutations of structural genes at the transcriptional level. Roots were harvested at four different developmental stages in four different colored carrots; yellow, orange, red, and purple. A total of seven genes in the carotenoid biosynthetic pathway were examined using RT-PCR. Regardless of different development stage, mRNA transcripts of all genes were detected but the level of expression appeared to be differential during root development. It has not been confirmed whether carrot phytoene synthase1 (PSY1) is an ortholog of tomato PSY1 and if carrot phytoene synthase2 (PSY2) is that of tomato PSY2, having the same transcriptional behavior. However, the phylogenetic relationship and deduced amino acid similarity showed carrot PSY2 was closely related to PSY1s in other crops, whereas carrot PSY1 was close to PSY2s. mRNA transcript of -carotene hydroxylase 2 was detected at fairly reduced level compared to other structural genes in the pathway. Our results suggested that carotenoid accumulation in carrot may be controlled by regulatory genes rather than structural genes in the pathway.
