Abstract
Shoot development in maize begins when meristematic, non-pigmented cells at leaf base stop dividing and proceeds toward the expanded green cells of the leaf blade. During this transition, promitochondria and proplastids develop into mature organelles and their DNA becomes fragmented. Changes in glycation damage during organelle development were measured for protein and DNA, as well as the glycating agent methyl glyoxal and the glycation-defense protein DJ-1 (known as Park7 in humans). Maize seedlings were grown under normal, non-stressful conditions. Nonetheless, we found that glycation damage, as well as defenses against glycation, follow the same developmental pattern we found previously for reactive oxygen species (ROS): as damage increases, damage-defense measures decrease. In addition, light-grown leaves had more glycation and less DJ-1 compared to dark-grown leaves. The demise of maize organellar DNA during development may therefore be attributed to both oxidative and glycation damage that is not repaired. The coordination between oxidative and glycation damage, as well as damage-response from the nucleus is also discussed.
Highlights
Shoot development in maize begins when meristematic, non-pigmented cells at leaf base stop dividing and proceeds toward the expanded green cells of the leaf blade
As well as countermeasures against glycation, follow the same developmental pattern found for reactive oxygen species (ROS): as damage increases, damage defense measures decrease
We previously reported that ROS levels in mitochondria, plastids, and whole cells increased during maize development from the basal meristem to the green leaf, whereas the levels of antioxidant agents declined during d evelopment[7]
Summary
Shoot development in maize begins when meristematic, non-pigmented cells at leaf base stop dividing and proceeds toward the expanded green cells of the leaf blade. The demise of maize organellar DNA during development may be attributed to both oxidative and glycation damage that is not repaired. We reported 8-hydroxydeoxyguanosine (8-oxoG) damage in maize orgDNA and found that it increased during development, as well as being higher in light- compared to dark-grown leaves[7]. There is another type of damage caused by the glycation of nucleic acids, proteins, and small molecules (see below). The dual role of DJ-1 makes it the only enzyme known to repair both proteins and nucleic acids
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