An indica pyramiding line, DK151, and its recurrent parent, IR64, were evaluated under drought stress and non-stress conditions for three consecutive seasons. DK151 showed significantly improved tolerance to drought. The DNA methylation changes in DK151 and IR64 under drought stress and subsequent recovery were assessed using methylation-sensitive amplified polymorphism analysis. Our results indicate that drought-induced genome-wide DNA methylation changes accounted for ∼12.1% of the total site-specific methylation differences in the rice genome. This drought-induced DNA methylation pattern showed three interesting properties. The most important one was its genotypic specificity reflected by large differences in the detected DNA methylation/demethylation sites between DK151 and IR64, which result from introgressed genomic fragments in DK151. Second, most drought-induced methylation/demethylation sites were of two major types distinguished by their reversibility, including 70% of the sites at which drought-induced epigenetic changes were reversed to their original status after recovery, and 29% of sites at which the drought-induced DNA demethylation/methylation changes remain even after recovery. Third, the drought-induced DNA methylation alteration showed a significant level of developmental and tissue specificity. Together, these properties are expected to have contributed greatly to rice response and adaptation to drought stress. Thus, induced epigenetic changes in rice genome can be considered as a very important regulatory mechanism for rice plants to adapt to drought and possibly other environmental stresses.

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This article describes the effect of addition of CeO 2 on the microstructure, hardness, and abrasive wear behaviour of Ni-based flame-sprayed coatings. These coatings are economical but not frequently used because of their high porosity, low hardness, and bigger grain size. The mechanical and tribological properties of the coatings are governed by the microstructure, grain size, and distribution of various elements. Rare earth elements (oxides) refine the microstructure. The commercially available Ni-based powder was modified with the addition of CeO 2 (0.4, 0.8, 1.2, 1.6, and 2 %wt). The conventional Ni-based coatings and those containing various amounts of CeO 2 were compared in terms of grain size and distribution of various elements, hardness, porosity, and abrasive wear behaviour. The addition of an optimal amount of CeO 2 (0.8 %wt) refines the grain size and improves hardness and abrasive wear resistance of the coatings. X-ray diffraction of the conventional and modified coating with an optimum addition of CeO 2 (0.8 %wt) was also carried out to identify the various phases present in the coating.