Expression of Genes of Circadian Rhythm, Activity of Photosystems, and Biosynthesis of Carotenoids in Seedlings of Two Inbred Corn Lines under Conditions of an Altered Photoperiod.

The plant circadian system, as a result of adaptive evolution, is closely related to sensitivity to photoperiod. Zea mays L. originally belongs to the short-day species, while modern cultivated maize accessions are considered neutral with respect to photoperiod. The work analyzes the impact of changing the long-day regime to ultrashort days and long nights on the level of transcripts of key circadian rhythm (GIGZ1A, GIGZ1B), photosystem I (psaA), photosystem II (psbA), and carotenoid biosynthesis (ZmPSY1, ZmPSY2, ZmLCYE, ORANGE-GREEN) genes in the leaves of two mid-late ripening inbred lines of corn (L-5580-1 and L-5739), similar in morphophysiological characteristics. In the same leaves, the content of chlorophylls and carotenoids was determined. It was found that the studied lines differ significantly in the dynamics of the gene transcript level and pigment content in response to a change in photoperiod. GIGZ1a and GIGZ1b expression increases 1 h after the end of the ultrashort day in both lines, and is then characterized by an increase or decrease depending on the line. Expression of photosystem psaA and psbA genes differs between lines, both in the level and dynamics of the response to a change in photoperiod. Activity of carotenogenesis genes ZmPSY1, ZmPSY2, ZmLCYE, and ORANGE-GREEN increases in both lines when day changes to night (except ZmPSY2 in L‑5580-1) and decreases to varying degrees depending on the line towards the end of the night period. The content of pigments 1 h after changing the regime increases in L-5580-1 and does not change in L-5739, and it decreases in both lines by the end of the night. The obtained data indicate the preservation of the circadian rhythm in L-5580-1 and increased adaptability of L-5739 and can be used to search for donors of the trait of high adaptability to changes in photoperiod among maize accessions. [ABSTRACT FROM AUTHOR]