Orchidaceae with ≈25,000 species of 800 genera is one of the largest families among angiosperms. Out of which, Dendrobium, Cymbidium, Vanda, and Phalaenopsis originated from Asia are considered as highly economical valued orchids. The chromosome/nuclear structure, especially with respect to the dynamics of rapidly evolving chromatin have been studied at various cell divisions including mitosis, meiosis and pollen mitosis in orchids. We investigated chromosomal distribution patterns of chromatin modifications with special emphasis on histone methylation, acetylation, phosphorylation, and centromere-specific histone 3 (CENH3) marks in orchids using immuno-FISH. The chromosomal distribution of 5-mC suggests that the genomic DNA of orchids is highly methylated and CG dinucleotide makes methylated hotspots on entire chromosomes. Various orchid species revealed diversified pattern of DNA methylation profile. Furthermore, such epigenetic regulatory post-translational histone modification marks not only function individually but also capable to act in combination as a unique pattern. The dual modified histone H3S10phK14ac that eventually targets the peri-centromeric position of chromosomes may serve as a new cytological marker to identify centromere in plants especially in orchids where the cytological/chromosomal preparations are very difficult. The chromosomal distribution of eu-/heterochromatic-specific histone marks as well as phosphorylation of H3S10 and H3T3 histone during pollen mitosis I in orchids have also been investigated. Detailed analysis suggest that the phosphorylation of histone plays a critical role in chromosome condensation events throughout pollen mitosis I in plants including orchids. Spatial distribution of chromatin environment that exists between different cell types such as diploid/polyploids, vegetative/generative cells has also been discussed.
Orchidaceae with ≈25,000 species of 800 genera is one of the largest families among angiosperms. Out of which, Dendrobium, Cymbidium, Vanda, and Phalaenopsis originated from Asia are considered as highly economical valued orchids. The chromosome/nuclear structure, especially with respect to the dynamics of rapidly evolving chromatin have been studied at various cell divisions including mitosis, meiosis and pollen mitosis in orchids. We investigated chromosomal distribution patterns of chromatin modifications with special emphasis on histone methylation, acetylation, phosphorylation, and centromere-specific histone 3 (CENH3) marks in orchids using immuno-FISH. The chromosomal distribution of 5-mC suggests that the genomic DNA of orchids is highly methylated and CG dinucleotide makes methylated hotspots on entire chromosomes. Various orchid species revealed diversified pattern of DNA methylation profile. Furthermore, such epigenetic regulatory post-translational histone modification marks not only function individually but also capable to act in combination as a unique pattern. The dual modified histone H3S10phK14ac that eventually targets the peri-centromeric position of chromosomes may serve as a new cytological marker to identify centromere in plants especially in orchids where the cytological/chromosomal preparations are very difficult. The chromosomal distribution of eu-/heterochromatic-specific histone marks as well as phosphorylation of H3S10 and H3T3 histone during pollen mitosis I in orchids have also been investigated. Detailed analysis suggest that the phosphorylation of histone plays a critical role in chromosome condensation events throughout pollen mitosis I in plants including orchids. Spatial distribution of chromatin environment that exists between d ...
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