Biologists at Washington University in St. Louis have identified the origin of a duplication in plants that allows them to override instructions coded in their DNA, potentially helping them adapt to environmental stresses. DNA methylation is a process that controls gene expression and traits in organisms, and in plants, it involves enzymes that add methyl groups to DNA to silence jumping genes that can cause damage. Plants have evolved multiple methylating enzymes, unlike mammals, with different enzymes focusing on different DNA contexts. Understanding this process could lead to innovations in agriculture by improving crop resilience.
Zhong’s research focuses on two enzymes found in plants, CMT3 and CMT2, both responsible for adding methyl groups to DNA but specializing in different DNA sequences. Through studying the model plant Arabidopsis thaliana, Zhong and her team discovered that CMT2 lost its ability to methylate certain DNA sequences due to a missing amino acid called arginine. By mutating CMT2 to reintroduce arginine, the enzyme regained its ability to methylate those sequences. This evolution from duplication provided plants with additional copies of genetic information, allowing for diversity and improved resilience to changing environmental conditions.
The unique structure of CMT2, with a flexible N-terminal region controlling protein stability, suggests that plants have evolved mechanisms for genome stability and environmental stress resistance. By studying whole-genome sequence variation in A. thaliana strains from the 1001 Genomes Project, researchers are able to analyze the genetic diversity that contributes to a plant species’ ability to thrive in different conditions. The diversity in methylation processes, including the regulation of jumping transposons, may play a vital role in helping plants adapt to harsh environmental conditions and stresses.
The research findings shed light on the evolutionary changes that have occurred in plants, particularly in the context of DNA methylation enzymes. By understanding how these enzymes have evolved different functions over time, researchers can gain insights into how plants have adapted to various environments worldwide. The duplication of enzymes like CMT2 has provided plants with backup systems and new capabilities that contribute to their resilience and ability to thrive in diverse conditions.
The ability to control gene expression and regulate traits through DNA methylation processes has significant implications for agriculture and crop improvement. By uncovering the mechanisms that plants have developed to adapt to environmental stresses, researchers can potentially leverage this knowledge to enhance crop resilience and develop more efficient strategies for crop improvement. By studying the evolutionary changes in DNA methylation enzymes, scientists can unlock the potential for innovations that support sustainable agriculture and food security in the face of changing environmental conditions.
