Scientists at the Sainsbury Laboratory have discovered how plants vary their response to heat stress depending on the time of day, solving a 79-year-old mystery.

Since 1939, it has been known that plants' response to heat stress fluctuates between day and night. The daily cycle of plant heat resistance is a strategy that protects plants from the hottest parts of the day, and prevents energy waste at night when it is cooler. Understanding plant response to heat stress is crucial for developing crops that can withstand rising average temperatures and more frequent heat waves under climate change. Dr. Patrick Dickinson, a research associate at the University of Cambridge's Department of Plant Sciences, discovered that a number of genes known to be involved in chloroplast formation were also having a big effect on the plant's response to high temperatures.

This discovery pointed to the chloroplast being involved in protecting the plant from heat. Dr. Dickinson discovered that there is a signal sent from the chloroplast in response to light, which then activates gene expression in the nucleus to make the plant resistant to heat stress. Dr. Dickinson says the signalling molecule is related to the photosynthetic electron transport chain, which is communicated to the nucleus to activate the gene expression, but that signal is not clear yet.

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Figure: Dr Patrick Dickinson discovered that there is a signal sent from the chloroplast in response to light, which activates gene expression in the nucleus to make plants resistant to heat stress.