ABSTRACT
To fully exploit selenium-rich land resources and ensure crop safety, the phenomenon of "double high" of Se and heavy metals in reclaimed soil of mining wasteland was studied. Soil and maize samples collected from "point-to-point" were weighted by the inverse distance weighted (IDW) method; multiple linear regression (MLR), partial least squares regression (PLSR), random forest regression (RFR), and other methods were used to predict selenium uptake by maize in a sulfur mine reclamation area in southwest China. Meanwhile, the antagonistic effects of selenium (Se) on heavy metals (Hg, As, Cd, and Cr) were analyzed. The results showed that the soil in the study area was rich in selenium resources. The average Se content in the soil reached 0.83 mg·kg-1, which was 2.87 times that of the average Se content in Chinese soil. The Se content in maize grains ranged from 0.02 mg·kg-1 to 0.16 mg·kg-1. According to correlation analysis and model prediction, the main influencing factors of selenium content in maize grains in the study area were soil selenium, pH value, organic matter, and heavy metal As. Multivariate linear regression (MLR) was the most effective method for predicting selenium content in maize grains, and the determinant coefficient R2 was 0.52. By comparing the enrichment characteristics of maize to heavy metals (Hg, As, Cd, and Cr) under different concentration gradients of Se in the soil of the study area, the results showed that Se had antagonistic effects on Hg, As, Cd, and Cr. The results can provide a basis for the development of selenium-rich agriculture in similar mining wasteland reclamation in the future.
ABSTRACT
Histone lysine methylation is known to be involved in the epigenetic regulation of gene expression in all eukaryotes including plants. Here we show that the rice SDG714 is primarily responsible for dimethylation but not trimethylation on histone H3K9 in vivo. Overexpression of YFP-SDG714 in Arabidopsis significantly inhibits plant growth and this inhibition is associated with an enhanced level of H3K9 dimethylation. Our microarray results show that many genes essential for the plant growth and development were downregulated in transgenic Arabidopsis plants overexpressing YFP-SDG714. By chromatin immunoprecipitation analysis, we show that YFP-SDG714 is targeted to specific chromatin regions and dimethylate the H3K9, which is linked with heterochromatinization and the downregulation of genes. Most interestingly, when YFP-SDG714 production is stopped, the inhibited plants can partially restore their growth, suggesting that the perturbation of gene expression caused by YFP-SDG714 is revertible. Taken together, our results point to an important role of SDG714 in H3K9 dimethylation, suppression of gene expression and plant growth, and provide a potential method to regulate gene expression and plant development by an on-off switch of SDG714 expression.
