The study shows that silencing of NOR2 rRNA genes in Arabidopsis thaliana depends primarily on CHH-context cytosine methylation, particularly mediated by CMT2 and the chromatin remodeler DDM1, rather than CG or CHG methylation. Comparative promoter analysis revealed a prevalence of CHH sites in plant rDNA promoters, explaining why CHH methylation mutants disrupt NOR2 silencing more strongly, while NOR2 loci are hyper‑methylated and more condensed than NOR4.
A maize near-isogenic line population designed for gene discovery and characterization of allelic effects
Authors: Zhong, T., Mullens, A., Morales, L., Swarts, K., Stafstrom, W., He, Y., Sermons, S., Yang, Q., Lopez-Zuniga, L. O., Rucker, E., Thomason, W., Nelson, R., Jamann, T. M., Balint-Kurti, P., Holland, J. B.
The study characterized 1,264 maize near‑isogenic lines derived from 18 donor inbreds crossed to the recurrent parent B73, using genotyping‑by‑sequencing and SNP‑chip data to detect 2,972 introgression segments via a novel hidden Markov model pipeline. Disease phenotyping enabled QTL mapping for foliar disease resistance, revealing extensive allelic variation among donor lines, and establishing the nNIL population as a valuable resource for dissecting complex traits in maize.