Abstract
Many plant physiological processes have diurnal patterns regulated by diurnal environmental changes and circadian rhythms, but the transcriptional underpinnings of many of these cycles have not been studied in major crop species under field conditions. Here, we monitored the transcriptome of field‐grown soybean (Glycine max) during daylight hours in the middle of the growing season with RNA‐seq. The analysis revealed 21% of soybean genes were differentially expressed over the course of the day. Expression of some circadian‐related genes in field‐grown soybean differed from previously reported expression patterns measured in controlled environments. Many genes in functional groups contributing to and/or depending on photosynthesis showed differential expression, with patterns particularly evident in the chlorophyll synthesis pathway. Gene regulatory network inference also revealed seven diurnally sensitive gene nodes involved with circadian rhythm, transcription regulation, cellular processes, and water transport. This study provides a diurnal overview of the transcriptome for an economically important field‐grown crop and a basis for identifying pathways that could eventually be tailored to optimize diurnal regulation of carbon gain.
Highlights
Diurnal changes in plant physiological responses and gene expression are governed by diurnally changing environmental conditions and endogenous circadian rhythms
Sufficient reads were counted for 36,059 genes to include in the analysis (Supporting information Dataset S1), which represents 64% of the 56,044 protein‐coding genes predicted in the soybean genome (Schmutz et al, 2010)
This diurnal picture of the field‐grown soybean transcriptome illustrates that genes in pathways either contributing to or depending on photosynthesis are often differentially transcribed over the course of the day
Summary
Diurnal changes in plant physiological responses and gene expression are governed by diurnally changing environmental conditions and endogenous circadian rhythms. Coordinating physiological functions with the 24‐h clock allows plants to balance energy needs and resources (Dodd et al, 2005) and creates temporal compartments to prevent futile biochemical cycles. Stomatal opening is stimulated by light to allow CO2 to enter the leaf (Kinoshita et al, 2001), which means transpiration occurs almost entirely in the light, driving water flow through the plant. Extra carbon must be assimilated to fuel respiration for cellular processes in the dark. This extra carbon is typically stored as starch in the chloroplast, resulting in diurnal cycles of starch accumulation and depletion (Stitt & Zeeman, 2012; Zeeman, Smith, & Smith, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
