Heat shock transcription factor (Hsf) gene family in common bean (Phaseolus vulgaris): genome-wide identification, phylogeny, evolutionary expansion and expression analyses at the sprout stage under abiotic stress

Background Common bean (Phaseolus vulgaris) is an essential crop with high economic value. The growth of this plant is sensitive to environmental stress. Heat shock factor (Hsf) is a family of antiretroviral transcription factors that regulate plant defense system against biotic and abiotic stress. To date, few studies have identified and bio-analyzed Hsfs in common bean. Results In this study, 30 Hsf transcription factors (PvHsf1–30) were identified from the PFAM database. The PvHsf1–30 belonged to 14 subfamilies with similar motifs, gene structure and cis-acting elements. The Hsf members in Arabidopsis, rice (Oryza sativa), maize (Zea mays) and common bean were classified into 14 subfamilies. Collinearity analysis showed that PvHsfs played a role in the regulation of responses to abiotic stress. The expression of PvHsfs varied across different tissues. Moreover, quantitative real-time PCR (qRT-PCR) revealed that most PvHsfs were differentially expressed under cold, heat, salt and heavy metal stress, indicating that PvHsfs might play different functions depending on the type of abiotic stress. Conclusions In this study, we identified 30 Hsf transcription factors and determined their location, motifs, gene structure, cis-elements, collinearity and expression patterns. It was found that PvHsfs regulates responses to abiotic stress in common bean. Thus, this study provides a basis for further analysis of the function of PvHsfs in the regulation of abiotic stress in common bean.

Genome-Wide Characterization of Sedum plumbizincicola HMA Gene Family Provides Functional Implications in Cadmium Response

Heavy-metal ATPase (HMA), an ancient family of transition metal pumps, plays important roles in the transmembrane transport of transition metals such as Cu, Zn, Cd, and Co. Although characterization of HMAs has been conducted in several plants, scarcely knowledge was revealed in Sedum plumbizincicola, a type of cadmium (Cd) hyperaccumulator found in Zhejiang, China. In this study, we first carried out research on genome-wide analysis of the HMA gene family in S. plumbizincicola and finally identified 8 SpHMA genes and divided them into two subfamilies according to sequence alignment and phylogenetic analysis. In addition, a structural analysis showed that SpHMAs were relatively conserved during evolution. All of the SpHMAs contained the HMA domain and the highly conserved motifs, such as DKTGT, GDGxNDxP, PxxK S/TGE, HP, and CPx/SPC. A promoter analysis showed that the majority of the SpHMA genes had cis-acting elements related to the abiotic stress response. The expression profiles showed that most SpHMAs exhibited tissue expression specificity and their expression can be regulated by different heavy metal stress. The members of Zn/Co/Cd/Pb subgroup (SpHMA1-3) were verified to be upregulated in various tissues when exposed to CdCl2. Here we also found that the expression of SpHMA7, which belonged to the Cu/Ag subgroup, had an upregulated trend in Cd stress. Overexpression of SpHMA7 in transgenic yeast indicated an improved sensitivity to Cd. These results provide insights into the evolutionary processes and potential functions of the HMA gene family in S. plumbizincicola, laying a theoretical basis for further studies on figuring out their roles in regulating plant responses to biotic/abiotic stresses.

Metabolic and Physiological Regulation of Aspartic Acid-Mediated Enhancement of Heat Stress Tolerance in Perennial Ryegrass

Aspartate is the most critical amino acid in the aspartate metabolic pathway, which is associated with multiple metabolic pathways, such as protein synthesis, nucleotide metabolism, TCA cycle, glycolysis, and hormone biosynthesis. Aspartate also plays an important role in plant resistance to abiotic stress, such as cold stress, drought stress, salt stress or heavy metal stress. This study found that the chlorophyll content and antioxidant active enzyme content (SOD, CAT, POD and APX) of perennial ryegrass treated with 2 mM aspartate were significantly higher than those treated with water under heat stress. The electrolyte leakage rate, MDA content and peroxide levels (O2− and H2O2) of perennial ryegrass treated with aspartate were significantly lower than those of perennial ryegrass treated with water, indicating that exogenous aspartate increases the content of chlorophyll, maintain the integrity of cell membrane system, and enhances SOD-CAT antioxidant pathway to eliminate the oxidative damage caused by ROS in perennial ryegrass under heat stress. Furthermore, exogenous aspartate could enhance the TCA cycle, the metabolism of the amino acids related to the TCA cycle, and pyrimidine metabolism to enhance the heat tolerance of perennial ryegrass.

The elemental defense effect of cadmium on Alternaria brassicicola in Brassica juncea

Background The elemental defense hypothesis states a new defensive strategy that hyperaccumulators defense against herbivores or pathogens attacks by accumulating heavy metals. Brassica juncea has an excellent ability of cadmium (Cd) accumulation. However, the elemental defense effect and its regulation mechanism in B. juncea remain unclear. Results In this study, we profiled the elemental defense effect and the molecular regulatory mechanism in Cd-accumulated B. juncea after Alternaria brassicicola infection. B. juncea treated with 180 mg Kg− 1 DW CdCl2 2.5H2O exhibited obvious elemental defense effect after 72 h of infection with A. brassicicola. The expression of some defense-related genes including BjNPR1, BjPR12, BjPR2, and stress-related miRNAs (miR156, miR397, miR398a, miR398b/c, miR408, miR395a, miR395b, miR396a, and miR396b) were remarkably elevated during elemental defense in B. juncea. Conclusions The results indicate that Cd-accumulated B. juncea may defend against pathogens by coordinating salicylic acid (SA) and jasmonic acid (JA) mediated systemic acquired resistance (SAR) and elemental defense in a synergistic joint effect. Furthermore, the expression of miRNAs related to heavy metal stress response and disease resistance may regulate the balance between pathogen defense and heavy metal stress-responsive in B. juncea. The findings provide experimental evidence for the elemental defense hypothesis in plants from the perspectives of phytohormones, defense-related genes, and miRNAs.

Effect of Nutrients on Diatom Growth: A Review

Diatoms are one of the unicellular algae with a rare presence of unaltered, durable, transparent and species-specific silica frustules that persist even after cell death in the deposits of water bodies. Diatom has high capacity for absorption of metals for maintaining the water quality and high rate of multiplication. These characters promoted the use of this microbial biomass for effluent detoxification. These diatoms can also solve metal toxicity problems in aquatic ecosystems in the water polluted environment. In the present review, the focus is on several nutrients (nitrogen, phosphorus, iron and silica) that are essential for the growth of diatoms at very low concentrations, but most of them are toxic at high concentrations. It also shows the relationship between heavy metal stress and lipid body induction which may be a valuable indicator for the evaluation of heavy metal contamination of fluvial ecosystems. HIGHLIGHTS Diatoms are eukaryotic, unicellular, photosynthetic, silica-containing microscopic algae with distinct geometric forms Diatoms are used for biomonitoring purposes for taxonomic and morphological properties of ecosystems, community and human disturbances Diatoms are also the primary producer of oil in the world responsible for fixing 25 % of CO2 and 30 % of crude oil diatoms Many diatoms are appropriate for lipid development up to 70 % of their body volume and are investigated for biofuel as a hotspot GRAPHICAL ABSTRACT

Extremophiles and Their Application in Bioremediation

A microorganism dwelling in severe environmental conditions is termed an extremophile. These unfavorable environmental conditions include high salinity, toxin compounds, heavy metals, unfavorable temperature, and extremely acidic and alkaline pH. Microorganisms belonging to prokaryotes include true bacteria and archaea bacteria which prevail in harsh environments. In recent years, extremophilic, basically, archaea bacteria have been reported for their immense potential application in the bioremediation process. Bioremediation is a technique that utilizes microorganisms for the decomposition of organic and inorganic pollutants; anthropogenic activities are the basic cause of soil pollution, water pollution, and air pollution globally. Extremophiles are capable of producing enzymes that are thermolabile and can function normally even in extreme conditions. These enzymes and proteins can be utilized in the bioremediation process under extreme pH, heavy metal stress, and unfavorable temperature conditions. In this chapter, the role of extremophiles in bioremediation is discussed.