Moderate DNA methylation changes associated with nitrogen remobilization and leaf senescence in Arabidopsis

O_LIThe lifespan of plants and tissues is restricted by environmental and genetic components. Following the transition to reproductive growth, leaf senescence ceases cellular life in monocarpic plants to remobilize nutrients to storage organs. C_LIO_LIWe observed altered leaf to seed ratios, faster senescence progression and enhanced nitrogen remobilization from the leaves in two methylation mutants (ros1 and the triple dmr1/2 cmt3 knockout). C_LIO_LIDNA methylation in wild type Col-0 leaves initially moderately declined with progressing leaf senescence, predominantly in the CG context, while the ultimate phase of leaf discoloration was associated with moderate de novo methylation of cytosines, primarily in the CHH context. C_LIO_LIRelatively few differentially methylated regions, including one in the ROS1 promoter linked to the down-regulation of ROS1, were present, but these were unrelated to known senescence-associated genes. C_LIO_LIDifferential methylation patterns were identified in transcription factor binding sites, such as the W-boxes that are targeted by WRKYs, which impaired transcription factor binding when methylated in vitro. C_LIO_LIMutants that are defective in DNA methylation showed distinct nitrogen remobilization, which was associated with altered patterns of leaf senescence progression. But moderate methylome changes during leaf senescence were not specifically associated with up-regulated genes during senescence. C_LI