Pollen thermotolerance by APX2-1

Global warming is a rising issue affecting the environmental balance between most life forms and their environment. The low crop productivity due to increased heat stress calls for solutions in plant biotechnology for developing means to make plants acclimatize to varying conditions and maintain plant yield simultaneously.

APX2 encodes a cytosolic ascorbate peroxidase that scavenges hydrogen peroxide in plant cells. It has been found that even though the mutant shows defective scavenging activity at the developmental stage, at the reproductive stage the absence of the gene improved pollen thermotolerance, protecting seed set formation under high temperatures. We recently found that HY5, known to function in light sensing pathways and directly regulate APX2 promoter activity, could be considered to play a role in pollen thermotolerance. These finding have led us to hypothesize that pollen may autonomously sense light mediating HY5 pathway that activates pollen HS responses.

The effect of light on APX2 expression was examined using APX2 promoter: GUS reporter lines verifying dependency on light involvement. The regulation of HY5 on APX2 protein level in pollen during heat stress is currently being evaluated. Furthermore, the potential impact of the apx2-1 mutation on HY5 is also being estimated using hy5 mutant expressing the APX2p: GUS reporter.

Since understanding pollen heat stress response is highly valuable for the future of agriculture and autonomous light sensing by pollen is virtually unknown, we are optimistic that our study will shed light on both processes.