Histone deacetylase OsHDA706 increases salt tolerance via H4K5/K8 deacetylation of OsPP2C49 in rice.

High salt is a major environmental factor that threatens plant growth and development. Increasing evidence indicates that histone acetylation is involved in plant responses to various abiotic stress; however, the underlying epigenetic regulatory mechanisms remain poorly understood. In this study, we revealed that the histone deacetylase OsHDA706 epigenetically regulates the expression of salt stress response genes in rice (Oryza sativa L.). OsHDA706 localizes to the nucleus and cytoplasm and OsHDA706 expression is significantly induced under salt stress. Moreover, oshda706 mutants showed a higher sensitivity to salt stress than the wild-type. In vivo and in vitro enzymatic activity assays demonstrated that OsHDA706 specifically regulates the deacetylation of lysines 5 and 8 on histone H4 (H4K5 and H4K8). By combining chromatin immunoprecipitation and mRNA sequencing, we identified the clade A protein phosphatase 2 C gene, OsPP2C49, which is involved in the salt response as a direct target of H4K5 and H4K8 acetylation. We found that the expression of OsPP2C49 is induced in the oshda706 mutant under salt stress. Furthermore, the knockout of OsPP2C49 enhances plant tolerance to salt stress, while its overexpression has the opposite effect. Taken together, our results indicate that OsHDA706, a histone H4 deacetylase, participates in the salt stress response by regulating the expression of OsPP2C49 via H4K5 and H4K8 deacetylation.

Genome-Wide Effects on Gene Expression Between Parental and Filial Generations of Trisomy 11 and 12 of Rice.

Aneuploid refers to the gene dosage imbalance due to copy number alterations. Aneuploidy is generally harmful to the growth, development and reproduction of organisms according to the numerous research. However, it has rarely been reported on whether aneuploid have a relevant pattern of genome expression between the parental and its offspring generations. In this study, mRNA sequencing analysis was performed on rice (Oryza sativa L.) primary trisomes 11 and 12, same primary trisomes and normal individuals in their filial generation. We systematically summarized the changes in gene expression patterns that occur on cis genes and on trans genes between parental and filial generations. In T11 and T12, the ratio of cis-gene expression showed intermediate type in parents and dosage compensation in filial generations, which maybe due to more genes being downregulated. The trans genes were also affected by aneuploidy and manifested as cis-related. The strains with normal chromosomes in filial generations, there are still aneuploid-sensitive genes differentially expressed in their genomes, indicating that the effect of aneuploidy is far-reaching and could not be easily eliminated. Meanwhile, among these differentially expressed genes, genes with low-expression level were more likely to be upregulated, while genes with medium- and high-expression level were easy to be downregulated. For the different types of rice aneuploid, upregulated genes were mainly associated with genomic imbalance while downregulated genes were mainly influenced by the specific added chromosome. In conclusion, our results provide new insights into the genetic characterization and evolution of biological aneuploidy genomes.