How do trees know when spring is coming and it's time to let the buds burst?

Rishikesh Bhalerao wants to understand how trees know when it's spring and time to restart growth by breaking buds. The timing of bud break is determined by warm weather which signals the onset of spring. However,, this requires trees to distinguish between temporary warm winter weather from the real onset of spring.

Understanding the molecular basis of this temperature sensing is the goal of project. Such knowledge will help us understand how climate change affects forests, forestry and the work with various environmental goals.

Warmer and more fluctuating temperatures are a threat to the world's forests. Tree species have been highly successful over millennia by adapting their growth patterns to regular annual seasonal changes using cues such as temperature. However, with long generation times, trees are highly susceptible to rapidly impending climate change.

A process that is particularly susceptible is the is timing of bud break in spring, a key trait of seasonal adaptation. The timing of bud break is crucial to tree survival. If bud break occurs prematurely in the spring, growing shoots will be damaged by low temperatures, whereas delayed bud break shortens the growing season and reduces the productivity of trees.

Rishikesh Bhalerao has shown that budburst is dependent on a long cold period, which helps the buds chart the progress and end of winter and then measure gradual warming to sense the spring onset and break buds at just the right time.

Important to separate spells of warm winter weather from the real onset of spring

Most molecular studies of bud break have so far been conducted under controlled conditions in greenhouses with constant temperature, but in nature temperatures vary constantly from day to day. Consequently, a major unanswered question is – how buds can read and interpret fluctuating temperature in order to robustly time their budburst in spring.

Initial studies suggest that small structures called plasmodesmata play a key role in communication between tree cells, and temperature fluctuations are likely to act on cell-cell communication to regulate bud break. Pioneering methods in cell biology, genomics and mathematical modelling will be used in a multidisciplinary approach to elucidate how cell-cell communication is regulated and linked with robust bud break regulation by a noisy temperature input.