The Content of Carotoids and the Expression Profile of Carotenoid Biogenesis Genes during Long-Term Cold Storage of Potato Tubers

Abstract

Carotenoids are secondary metabolites that are synthesized and stored in all types of plant plastids. These pigments play a significant role in protection against oxidative stress, as well as in the color of flowers and sink organs. Tubers of potato Solanum tuberosum L. synthesize carotenoids, including during post-harvest storage. The state of physiological dormancy and cold stress response are controlled, among other things, by abscisic acid (ABA), which is an apocarotenoid. In this study, we analyzed the expression of carotenoid biogenesis pathway genes (PSY1, PSY2, PSY3, PDS, ZDS, Z-ISO, CRTISO, LCYB1, LCYB2, LCYE, VDE, ZEP, NSY, NCED1, NCED2, and NCED6), as well as genes putatively involved in initiation of chromoplast differentiation (OR1 and OR2), in the dynamics of long-term cold storage (September, February, April) of tubers of potato cultivars Barin, Utro, Krasavchik, Sevemoe siyanie and Nadezhda. It was shown that OR1, and OR2 mRNAs are present in tubers of all cultivars at all stages of storage. The expression profile of all analyzed carotenoid biosynthesis genes during tuber storage was characterized by a significant decrease in transcript levels in February compared to September, with some exceptions. In the period from February to April, the level of gene transcripts changed insignificantly. The biochemical analysis of the carotenoid content in the dynamics of cold storage showed that at the time of harvesting, the highest carotenoid content was in tubers of the cv. Utro; tubers of other cultivars were characterized by a similar amount of carotenoids. During storage from September to April, the total carotenoids changed in a genotype-dependent manner without any trend common to all cultivars.