500 / 2019-02-28 17:45:04

Pollen fertility and the role of ROS and redox homeostasis in heat stress tolerance

flow cytometry,Pollen,ROS,Heat stress,redox,ascorbate proxidase,auxin,flavonols

全体主题 > Abiotic Stress

In many plants, pollen development and fertilization are considered most sensitive to heat stress (HS), which often leads to male sterility.
The ascorbate peroxidase 2 (APX2) enzyme is an important ROS/redox regulator in the HS response (HSR) in Arabidopsis thaliana and other plants. While APX2 expression is male organ- and pollen-specific during reproductive development, APX2 deficient pollen gained increased thermotolerance, accounting for increased seed set under these conditions. Using our recently-developed flow cytometry approach, we show differences in pollen viability, ROS and redox status between the apx2 mutant and WT at the population scale. This approach also demonstrated that pollen is distributed bimodally into ‘low-ROS’ and ‘high-ROS’ subpopulations, supporting a model in which a significant fraction of a flower’s pollen remains in a low-metabolic or dormant state, which may serve as a stress avoidance strategy. Transcriptomics comparison between apx2 and WT, pollen and leaves, identified nearly 1,400 apx2 pollen-specific transcriptional changes, indicating extensive reprogramming that includes activation of the phenylpropanoids and auxin pathways. Follow-up experiments support the involvement of flavonol biosynthesis, auxin signaling, and redox regulation in the HS tolerance mechanism of apx2 pollen. Our work provides new insights into pollen HSR, which could contribute to increasing food security in the face of the current trend of global climate change.