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The genome of plants is organized into chromatin. The chromatin structure regulates the rates of DNA metabolic processes such as replication, transcription, DNA recombination, and repair. Different aspects of plant growth and development are regulated by changes in chromatin status by the action of chromatin-remodeling activities. Recent data have also shown that many of these chromatin-associated proteins participate in different aspects of the DNA damage response, regulating DNA damage and repair, cell cycle progression, programmed cell death, and entry into the endocycle. In this review, we present different examples of proteins and chromatin-modifying enzymes with roles during DNA damage responses, demonstrating that rapid changes in chromatin structure are essential to maintain genome stability. [ABSTRACT FROM AUTHOR]

In situimmunolocalization and Western blot analysis of separated cellular and subcellular fractions, were used to determine the localization of different isoforms of NADP-malic enzyme in both wheat (C3) and maize (C4) plants. In both techniques, an affinity purified anti-(maize 62 kDa NADP-ME) lgG from the maize green leaf isoform also reacted with a 72 kDa protein in tissues of C4 plants as well as C3 plants. The light- inducible 62 kDa isofomi is located in bundle sheath chioroplasts of maize leaves. In etiolated leaves and in roots of maize there is evidence for the occurrence of a 72 kDa isoform which co-migrates on 2-D (SDS and isoelectric focusing) PAGE. The 72 kDa isoform is also present in low levels in green leaves. This form may occur in multiple intracellular compartments; but in situ immunolocalization experiments and Western blot and activity assays on fractionated protoplasts indicate that a significant amount of this isoform occurs in plastids. With regards to C3 plants such as wheat, a 72 kDa isoform in leaves is largely confined to the chloroplasts based on in situ immunolocalization and Western blots and enzyme activity assays with fractionated protoplasts. In maize, it appears that the constitutive expression pattern of a possible C3 ancestral gene for NADP-malic enzyme has been maintained, and a high level expression of a light-inducible isoform located in bundle sheath chloroplasts (62 kDa) has been acquired during its evolution. [ABSTRACT FROM PUBLISHER]