Field microenvironments regulate crop diel transcript and metabolite rhythms

Abstract

O_LIMost research in plant chronobiology was done in laboratory conditions. However, they usually fail to mimic natural conditions and their slight fluctuations, highlighting or obfuscating rhythmicity. High-density crops, such as sugarcane (Saccharum hybrid), generate field microenvironments with specific light and temperature due to mutual shading. C_LIO_LIWe measured the metabolic and transcriptional rhythms in the leaves of 4-month-old (4 mo) and 9 mo sugarcane grown in the field. Most of the assayed rhythms in 9 mo sugarcane peaked >1 h later than in 4 mo sugarcane, including rhythms of the circadian clock gene, LATE ELONGATED HYPOCOTYL (LHY). C_LIO_LIWe hypothesized that older sugarcane perceives dawn later than younger sugarcane due to self-shading. As a test, we measured LHY rhythms in plants on the east and the west side of a field. We also tested if a wooden wall built between lines of sugarcane changed their rhythms. The LHY peak was delayed in the plants in the west of the field or beyond the wall; both shaded at dawn. C_LIO_LIWe conclude that plants in the same field may have different phases due to field microenvironments, impacting important agronomical traits, such as flowering time, stalk weight and number. C_LI