Abstract
Chromium (Cr) is a heavy metal in nature, which poses a potential risk to toxicity to both animals and plants when releasing into the environment. However, the regulation of microRNA (miRNA)-mediated response to heavy metal Cr has not been studied in Miscanthus sinensis. In this study, based on high-throughput miRNA sequencing, a total of 104 conserved miRNAs and 158 nonconserved miRNAs were identified. Among them, there were 45 differentially expressed miRNAs in roots and 13 differentially expressed miRNAs in leaves. The hierarchical clustering analysis showed that these miRNAs were preferentially expressed in a certain tissue. There were 833 differentially expressed target genes of 45 miRNAs in roots and 280 differentially expressed target genes of 13 miRNA in leaves. After expression trend analysis, five significantly enriched modules were obtained in roots, and three significantly enriched trend blocks in leaves. Based on the candidate gene annotation and gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) function analysis, miR167a, novel_miR15, and novel_miR22 and their targets were potentially involved in Cr transportation and chelation. Besides, miR156a, miR164, miR396d, and novel_miR155 were identified as participating in the physiological and biochemical metabolisms and the detoxification of Cr of plants. The results demonstrated the critical role of miRNA-mediated responses to Cr treatment in M. sinensis, which involves ion uptake, transport, accumulation, and tolerance characteristics.
Highlights
Heavy metal pollution of soil could lead to losses in agricultural yields and potentially affects human health when it enters the food chain, which has become one of the major ecological problems worldwide (Islam et al, 2014)
According to the preliminary experiment, the morphology of M. sinensis was completely established after 4 months (Nie et al, 2017), and the phenotypic change was most obvious under 200 mg/L of Cr stress based on the study by Arduini et al (2006)
After sequencing with previously cultured M. sinensis materials that were grown under 0 h Cr treatment (ML0 and MR0), 12 h Cr treatment (ML12 and MR12), 24 h Cr treatment (ML24 and MR24), and 72 h Cr treatment (ML72 and MR72), a total of 24 small RNA libraries were established to identify and predict the miRNAs associated with Cr treatment
Summary
Heavy metal pollution of soil could lead to losses in agricultural yields and potentially affects human health when it enters the food chain, which has become one of the major ecological problems worldwide (Islam et al, 2014). Chromium (Cr) is a heavy metal by nature with trivalent Cr (III) and hexavalent Cr (VI) as two major stable chemical forms, which poses a potential risk to toxicity to both animals and plants when releasing into the environment (Tiwari et al, 2013). Cr (VI) compounds are known to have stronger oxidizing activity than Cr (III), and excessive accumulation in plants can cause extremely deleterious effects on Chromium Tolerance of M. sinensis morphological, physiological, and biochemical processes of plants, such as inhibition of seed germination and plant growth, damage of cell ultrastructure, induction of oxidative stress, and uptake of mineral nutrition (Rout et al, 2000; Dube et al, 2003; Choudhury and Panda, 2005; Shanker et al, 2005; Panda, 2007; Diwan et al, 2010). To manage Cr contamination and limit Cr accumulation in crops, it is necessary to gain a better understanding of the uptake, transportation, and sequestration of Cr and of the adaptive response of plants to the stress
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