Biotic and Abiotic Stress: A triggering factor for breaking pollen dormancy

Pollen development and its viability plays a major role in angiosperms. Upon evaluation of pollen viability (in Arabidopsis or MicroTom) using flow cytometry of DCF-stained (dichlorodihydrofluorescein diacetate; a ROS probe), we discovered that pollen is distributed bimodally into ‘low-ROS’ and ‘high-ROS’ subpopulations, corresponding to low and high metabolic activity of the pollen grains, respectively. While the active high-ROS pollen is extremely sensitive to heat stress, low-ROS pollen displays relative tolerance of high temperatures. We hypothesize that low-ROS pollen are in a dormant state, serving as an adaptive strategy to avoid abiotic stress; demonstrate lowered metabolic profile or dormant even upon hydration.

Interestingly, under heat stress or pathogen attack, the DCF-stained pollen ROS populations both in Arabidopsis and MicroTom, seem to `shift` or increase metabolic activity towards the level of the `high ROS` subpopulation. This led us to hypothesize that stress might also trigger the low ROS pollen to break dormancy.

Though we have preliminary results to emphasize the hypothesis, furthermore evaluation and different approaches are being examined to gain support.