Warm nights disrupt transcriptome rhythms in field-grown rice panicles

In rice, a small increase in nighttime temperature reduces grain yield and quality. How warm nighttime temperatures (WNT) produce these detrimental effects is not well understood, especially in field conditions where the typical day-to-night temperature fluctuation exceeds the mild increase in nighttime temperature. We observed genome-wide disruption of gene expression timing during the reproductive phase in field-grown rice panicles acclimated to 2 to 3 degrees C WNT. Transcripts previously identified as rhythmically expressed with a 24-h period and circadian-regulated transcripts were more sensitive to WNT than were nonrhythmic transcripts. The systemwide perturbations in transcript levels suggest that WNT disrupt the tight temporal coordination between internal molecular events and the environment, resulting in reduced productivity. We identified transcriptional regulators whose predicted targets are enriched for sensitivity to WNT. The affected transcripts and candidate regulators identified through our network analysis explain molecular mechanisms driving sensitivity to WNT and identify candidates that can be targeted to enhance tolerance to WNT.

Automated summary

The increase in nighttime temperatures has detrimental effects on rice grain yield and quality, with warmer nighttime temperatures disrupting gene expression timing and reducing productivity. Transcripts with a 24-hour periodicity and circadian-regulated transcripts are more sensitive to warm nighttime temperatures, suggesting a disruption in the temporal coordination between internal molecular events and the environment. Identification of transcriptional regulators and affected transcripts through network analysis provides insight into the molecular mechanisms driving sensitivity to warm nighttime temperatures and potential targets for enhancing tolerance.