Large Scale Analysis of Gene Expression Under Circadian Rhythms from Distinct Photoperiods Conditions in Sugarcane (Saccharum sp)

Sugarcane (genus Saccharum) is an important agricultural commodity for consumable sugar and as a source of ethanol for renewable energy. Photoperiod perception connects clock regulatory genes to carbohydrate biosynthesis, thus, sugar output is adapted dynamically to environmental cues. Since carbohydrate output is linked to length of night, we wished to learn which gene-expression programs were modified in an experimentally controlled system of long versus normal night. We performed RNA-seq analysis on young plants habituated to a regime of control (12h/12h, C) or long-night (8h/16h, T) photoperiod. We collected RNA from leaves at seven time-points from early morning to end of the night. Differential expression analysis comparing T/C plants through the time-course showed more repressed genes in long-night samples at every time-point. Hierarchical clustering showed late-day samples from both conditions formed an out-group.Principal component analysis suggests a habituated gene-expression response to photoperiod in all time points and at least three cyclic patterns of gene-expression that differ between C and T. Preliminary analysis identified 2494 and 2945 rhythmic genes under C and T conditions, respectively. The eventual integration of this knowledge with biotechnology tools, we expect, will lead to more adaptative and productive sugarcane crops.