Mitigating Yield Loss Under Global Warming

Ma et al. investigate epigenetic aspects of heat-induced male sterility in cotton.

By Yizan Ma, Ling Min and Xianlong Zhang

Background:  Global warming causes extremely high temperatures in summer in some areas. Certain crops cultivated in summer cannot tolerate extreme heat stress and begin to show male sterility (which means there is no active pollen in the flower). DNA methylation is an epigenetic biochemical process that plays an important regulatory role in many aspects of plant growth and development, including flower development, fruit ripening, and stress responses. We know that DNA methylation changes under heat stress in flowers, but we don’t know why this occurs, or how it leads to male sterility.

Question: Upland cotton (Gossypium hirsutum) is cultivated in summer and can suffer from heat stress. We used cotton to investigate how heat stress disrupts DNA methylation in the flowers, and how the disrupted DNA methylation results in male sterility.

Findings: We found that a heat-tolerant line of cotton showed higher DNA methylation levels whereas a heat-sensitive line showed reduced DNA methylation level under heat stress. In the heat-sensitive line, the establishment of DNA methylation was disordered, so that the DNA methylation was very low in the early developmental stage. We further found that the low levels of DNA methylation were associated with elevated consumption of starch and abnormally high accumulation of reactive oxygen species. This abnormal metabolism caused by disordered DNA methylation may result in pollen sterility.

Next steps: We aim to investigate why DNA methylation was disrupted under high temperature stress. Specifically, which genes control the different methylation patterns in different cotton lines and how(what is the mechanism of action)?

Ma et al. (2018). Disrupted Genome Methylation in Response to High Temperature has Distinct Affects on Microspore Abortion and Anther Indehiscence. Plant Cell

Key Words: DNA methylation; high temperature; pollen fertility; anther dehiscence.