A team at Salk has shown that the CLASSY gene family decides which parts of the genome are turned off in a tissue-specific manner. The CLASSYs essentially control where the genome is marked by DNA methylation. The addition of methyl chemical groups to the DNA that act like turning off. As DNA methylation exists across diverse organisms like plants and animals. The research has implications for agriculture and medicine. The research was published in Nature Communications. The research identifies the CLSY genes as major factors behind epigenetic diversity in plant tissues.
The study of DNA methylation is under the field of epigenetics. Molecular modifications change how the DNA functions without changing the DNA sequence itself. It builds cell identity in a developing embryo but can cause cancer later in life. Defects in DNA methylation in plants can cause developmental defects and negatively impact crop yields.
DNA methylation is regulated by certain types of small RNAs. Scientists have worked with the model plant Arabidopsis thaliana. They have discovered the CLASSY gene family acts at different locations depending on the tissue. This reveals how diverse patterns of methylation are generated during plant development.
This research expands on a previous study, in which scientists found Arabidopsis, the CLSY genes determine which sites in the genome are methylated. The recent study focuses on whether this process can result in different methylation patterns in different Arabidopsis tissues.
Scientists found that CLSY genes were expressed differently depending on the plant tissue type. All four CLSY genes were expressed in flower buds. But CLSY3 was strongly expressed in ovules. CLSY1 was expressed in leaf and rosette tissues.
Scientists compared plants with mutant CLSY genes against wild-type plants. They found out that different combinations of CLSY family members controlled small RNA and DNA methylation patterns at thousands of sites throughout the genome, by depending on the tissue. Scientists said, this research demonstrated the CLSY genes’ role in shaping the tissues’ epigenetic landscape.