Identification of key genes and modules in response to Cadmium stress in different rice varieties and stem nodes by weighted gene co-expression network analysis

Abstract Soil cadmium (Cd) pollution threatens food safety. This study aimed to identify genes related to Cd accumulation in rice. Low- (Shennong 315, short for S315) and high- (Shendao 47, short for S47) Cd-accumulative rice cultivars were incubated with CdCl2·2.5H2O. RNA-seq and weighted gene co-expression network analysis (WGCNA) were performed to identify the modules and genes associated with Cd-accumulative traits of rice. After Cd stress treatment, the Cd content in various tissues of S315 was significantly higher than that of S47. In the stem nodes, the Cd distribution results of the two varieties indicated that the unelongated nodes near the root (short for node A) had a stronger ability to block Cd transfer upwards than the panicle node (short for node B). Cd stress induced huge changes in gene expression profiles. After analyzing the differentially expressed genes (DEGs) in significantly correlated WGCNA modules, we found that genes related to heavy metal transportation had higher expression levels in node A than that in node B, such as Copper transporter 6 (OS04G0415600), Zinc transporter 10 (OS06G0566300), and some heavy-metal associated proteins (OS11G0147500, OS03G0861400, and OS10G0506100). In the comparison results between S315 and S47, the expression of chitinase (OS03G0679700 and OS06G0726200) was increased by Cd treatment in S315. In addition, OsHSPs (OS05G0460000, OS08G0500700), OsHSFC2A (OS02G0232000), and OsDJA5 (OS03G0787300) were found differentially expressed after Cd treatment in S315, but changed less in S47. In summary, different rice varieties have different processes and intensities in response to Cd stress. The node A might function as the key tissue for blocking Cd upward transport into the panicle via vigorous processes, including of heavy metal transportation, response to stress, and cell wall

Combination of Water-Saving Irrigation and Nitrogen Fertilization Regulates Greenhouse Gas Emissions and Increases Rice Yields in High-Cold Regions, Northeast China

Increased rice production, which benefitted from cropping areas expansion and continuous N applications, resulted in severe increases in greenhouse gases (GHG) emissions from 1983 to 2019 in Heilongjiang Province, China. Therefore, field trials were performed in the high-cold Harbin region, Northeast China, to determine the efficiency of incorporating water regimes with N fertilization in minimizing the impact of rice production on GHG emissions. Two water-saving irrigation strategies, intermittent irrigation (W1) and control irrigation (W2), were used relative to continuous flooding (W0), and we combined them with six fertilized treatments. Our results demonstrated that W1 and W2 significantly decreased seasonal CH4 emissions by 19.7–30.0% and 11.4–29.9%, enhanced seasonal N2O emissions by 77.0–127.0% and 16.2–42.4%, and increased significantly yields by 5.9–12.7% and 0–4.7%, respectively, compared with W0. Although trade-offs occurred between CH4 and N2O emissions, W1 and W2 resulted in significant reductions in global warming potential (GWP). Moreover, low N rates (<120 kg N ha−1) performed better in GWP than high N rates. N fertilization and irrigation regimes had remarkable effects on rice yields and GWP. In conclusion, the incorporation of W1 and a N application under 120 kg N ha−1 could simultaneously mitigate GWP while enhancing production in black soils in high-cold Northeast China

ECD1 functions as an RNA-editing trans-factor of rps14-149 in plastids and is required for early chloroplast development in seedlings

Chloroplast development is a highly complex process and the regulatory mechanisms have not yet been fully characterized. In this study, we identified Early Chloroplast Development 1 (ECD1), a chloroplast-localized pentatricopeptide repeat protein (PPR) belonging to the PLS subfamily. Inactivation of ECD1 in Arabidopsis led to embryo lethality, and abnormal embryogenesis occurred in ecdl/+ heterozygous plants. A decrease in ECD1 expression induced by RNAi resulted in seedlings with albino cotyledons but normal true leaves. The aberrant morphology and under-developed thylakoid membrane system in cotyledons of RNAi seedlings suggests a role of ECD1 specifically in chloroplast development in seedlings. In cotyledons of ECD1-RNAi plants, RNA-editing of rps14-149 (encoding ribosomal protein S14) was seriously impaired. In addition, dramatically decreased plastid-encoded RNA polymerase-dependent gene expression and abnormal chloroplast rRNA processing were also observed. Taken together, our results indicate that ECD1 is indispensable for chloroplast development at the seedling stage in Arabidopsis

Synthesis and magnetic properties of Fe3C-C core-shell nanoparticles

FeC-C core-shell nanoparticles were fabricated on a large scale by metal-organic chemical vapor deposition at 700 °C with ferric acetylacetonate as the precursor. Analysis results of x-ray diffraction, transmission electron microscope and Raman spectroscope showed that the FeC cores with an average diameter of ∼35 nm were capsulated by the graphite-like C layers with the thickness of 2-5 nm. The comparative experiments revealed that considerable FeO-FeC core-shell nanoparticles and C nanotubes were generated simultaneously at 600 and 800 °C, respectively. A formation mechanism was proposed for the as-synthesized core-shell nanostructures, based on the temperature-dependent catalytic activity of FeC nanoclusters and the coalescence process of FeC-C nanoclusters. The FeC-C core-shell nanoparticles exhibited a saturation magnetization of 23.6 emu g and a coercivity of 550 Oe at room temperature