Studying the importance of biological rhythms for the ecological performance of plants

Ian Baldwin has received an Advanced Grant of the European Research Council. A total of 2.49 million euros will be provided for new jobs for scientists and technicians as well as laboratory equipment to work on a research project with plants called "Clockwork Green." The planned ecological field experiments in the USA will include plants genetically modified to make their internal circadian clock out of tune with their environment at each stage in their life cycle.

The central question of the 5-year project starting in April 2012 is whether these "arrhythmic" plants whose circadian clocks no longer work can survive in the wild. In other words, much like the night-shifted dysfunctional character in the movie Clockwork Orange whose behavioral abnormalities could be elicited by Beethoven's music, in Clockwork Green Baldwin and his team of researchers will use genetic and chemical tools to elicit arrhythmicity and study its consequences for a native plant in its native community.

Ecological Performance is all about timing

Whether an organism survives or dies in a particular habitat depends on whether it can do the right thing at the right time. In other words, timing is essential for survival. All organisms have a cellular clock and in many species from the different kingdoms of fungi, insects, plants, and even in humans, the mechanism of the molecular clock is becoming increasingly well understood. The circadian biological clock is thought to guarantee an optimal adaptation to prevailing environmental conditions but this has never been examined before in an organism growing under real world conditions.

Plants – primary producers

Plants are the foundation of most terrestrial food chains. They use solar energy to produce sugars, starch, protein and fat, on which all heterotrophic life forms depend: fungi as well as rabbits consuming leaves. The circadian rhythms of plants are well studied: leaf movements, the opening and closing of stomata, and photosynthetic metabolism, are all processes regulated by an endogenous clock. Daily cycles can also be clearly seen in the patterns of gene expression. Interestingly, more than 30% of all plant genes (plant genomes typically harbor 25,000 genes) are under circadian regulation. However, the function and circadian regulation of most of these genes is still unknown. What role do they play for the plants' survival and reproduction and how crucial is the circadian control of their expression?

These are the central questions in the project "Clockwork Green". Transgenic tobacco plants will be used whose biological clocks no longer work, because one of the many "clock genes", such as NaTOC1, has been silenced. These plants will be released in their natural habitat, the Great Basin Desert in Utah, USA, where they will grow together with wild and unmodified tobacco plants. All stages of plant development – from germination to seed formation in the flowers – will be studied. In addition, different ecological parameters, such as the intensity of infestation by herbivores and microbial pathogens, will be defined and the behavior of pollinators will be observed. Simultaneously, genetic, metabolic and physiological measurements will be conducted in "rhythmic" and "arrhythmic" plants.

The results will offer valuable clues to which genes are regulated by the biological clock and which are required for optimal plant growth and development. It is possible that different genes take over vital functions depending on the stage of life (germination – leaf development – flower formation – pollination – seed filling). The "timing" of plant growth plays an important role in agriculture – for example for synchronized seed germination or flowering in grains and oilseeds. Therefore the project may produce interesting results with applications in agriculture.

Provided by Max Planck Institute for Chemical Ecology