GENOMICS APPROACHES FOR IMPROVING NUTRITIONAL QUALITY OF FOOD CROP SPECIES
Location: Plant, Soil and Nutrition Research
Title: Regulatory control of high levels of carotenoid accumulation in potato tubers
Submitted to: Plant, Cell & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 2011
Publication Date: June 15, 2011
Citation: Zhou, X., Mcquinn, R., Fei, Z., Wolters, A., Van Eck, J., Brown, C.R., Giovannoni, J.J., Li, L. 2011. Regulatory control of high levels of carotenoid accumulation in potato tubers. Plant, Cell & Environment. 34:1020-1030.
Interpretive Summary: Carotenoids are indispensable for human nutrition and health. Potato as the world’s fourth largest crop generally contains low levels of carotenoids. Thus, a comprehensive understanding of the regulation of carotenoid accumulation in potato tubers is critical in providing novel strategies for development of carotenoid-enriched potato cultivars. This study was carried out to decipher the key factors controlling carotenoid levels in potato tubers using a combination of biochemical, molecular, and genomics approaches. Our results indicate that carotenoid accumulation in potato tubers is due to a combination of increased metabolic flux into the carotenoid biosynthetic pathway as well as the transcriptional control of a number of carotenoid metabolic genes. The synergistic effect of elevated expression of upstream genes and suppressed expression of downstream genes is responsible for specific carotenoid accumulation in yellow-flesh varieties.
Potato (Solanum tuberosum L.) tubers contain a wide range of carotenoid content. To decipher the key factors controlling carotenoid levels in tubers, four potato lines (Atlantic, Désirée, 91E22, and POR03) were examined by a combination of biochemical, molecular, and genomics approaches. These lines contained incremental levels of carotenoids, which were found to be associated with enhanced capacity of carotenoid biosynthesis as evident from norflurazon treatment. Microarray analysis of high and low carotenoid lines (POR03 vs. Atlantic) revealed 381 genes that showed significantly differential expression. The carotenoid metabolic pathway genes Beta-carotene hydroxylase 2 (BCH2) and Beta-carotene hydroxylase 1 (BCH1), along with zeaxanthin epoxidase (ZEP), and carotenoid cleavage dioxygenase 1A (CCD1A) were among the most highly differentially expressed genes. The transcript levels of BCH2 and BCH1 were lowest in Atlantic and highest in POR03, whereas those of ZEP and CCD1A were high in low carotenoid lines and low in high carotenoid lines. The high expression of BCH2 in POR03 line was associated with enhanced response to sugars. Our results indicate that high levels of carotenoid accumulation in potato tubers were due to an increased metabolic flux into the carotenoid biosynthetic pathway, as well as the differential expression of carotenoid metabolic genes.