SaHsfA4c From Sedum alfredii Hance Enhances Cadmium Tolerance by Regulating ROS-Scavenger Activities and Heat Shock Proteins Expression

Abstract

The heat shock transcription factor (Hsf) family, an important member in plant stress response, affects cadmium (Cd) tolerance in plants. In this study, we identified and functionally characterized a transcript of the Hsf A4 subgroup from Sedum alfredii. Designated as SaHsfA4c, the open reading frame was 1,302 bp long and encoded a putative protein of 433 amino acids containing a complete DNA-binding domain (DBD). Heterologous expression of SaHsfA4c in yeast enhanced Cd stress tolerance and accumulation, whereas expression of the alternatively spliced transcript InSaHsfA4c which contained an intron and harbored an incomplete DBD, resulted in relatively poor Cd stress tolerance and low Cd accumulation in transgenic yeast. The function of SaHsfA4c under Cd stress was characterized in transgenic Arabidopsis and nonhyperaccumulation ecotype S. alfredii. SaHsfA4c was able to rescue the Cd sensitivity of the Arabidopsis athsfa4c mutant. SaHsfA4c reduced reactive oxygen species (ROS) accumulation and increased the expression of ROS-scavenging enzyme genes and Hsps in transgenic lines. The present results suggest that SaHsfA4c increases plant resistance to stress by up-regulating the activities of ROS-scavenging enzyme and the expression of Hsps.

CaHsfA1d Improves Plant Thermotolerance via Regulating the Expression of Stress- and Antioxidant-Related Genes

“…To defend plant cells from oxidative injury, plants have developed various detoxification systems including ascorbic acid, water-soluble reductants, glutathione, as well as antioxidant enzymes involving ROS scavengers, such as POD, CAT, and APX [ 63 , 64 ]. Previous studies have strongly demonstrated the connection between antioxidant enzymes and Hsfs in scavenging ROS [ 63 , 65 , 66 ]. For instance, Arabidopsis Hsf3 was involved in modulating the expression of APX2 to scavenge H 2 O 2 [ 67 ].…”

Variation of Response Patterns Associated with an Avirulent Plant Symbiont Directed Defense Gene Expressions in Maize Exposed to Toxic Elements

“…Given the metal(oid) uptake and/or transport was reported to be more a quantitative trait subject to crosstalk of multiple genes and the regulation of HM transport/tolerance in plants requires more than one physiological pathway (8), of particular interest, the transcriptional expression pattern of an aquaporin gene and analogue mechanisms of one of the enzymatic antioxidants (peroxidase1) and stress proteins, protecting enzyme malfunction (HSP1) were chosen to be analyzed and confirmed by quantitative PCR. While PODs are one of the major enzymatic antioxidants catalyzing the breakdown of H 2 O 2 to scavenge radicals, or sometimes generating H 2 O 2 themselves as signal molecules (34), the HSPs are the quality controllers of PODs , assisting conformational changes (35). They belong to multi-gene superfamilies whose proteins are present in the mitochondria or chloroplasts showing induced expression not only by thermostress but also by HMs (35).…”

“…To find evidence for a possible connection and/or interlinking between combined HM stress, TS143 bio-stimulation, and plant response against an oxidative burst caused by ROS, four experimental groups with maize seedlings were prepared to test the protection potential of the target strain under As, Cd, Cu, Pb, Znapplied conditions. In this context, the mRNA expression profiles of previously identified defense gene expressions reported to be induced by different HMs (34) were analyzed (yet, despite these proteins conferring putative trace element caused stress tolerance, HSP, PIP, and POD-encoding genes cannot be listed as sole protection components for HMs). Activation under HM mix conditions in the gene encoding ZmPIP1-5 (1.40-fold), ZmHSP1 (1.8fold) and ZmPOD1 (5.55-fold) respectively showed molecular evidence of cellular damage that overlapped with phenotypic changes (Figure 2).…”

Research on the Mechanisms of Plant Enrichment and Detoxification of Cadmium

“…HSP maintains normal cell metabolism by upregulating the activity of ROS scavenging enzymes (including antioxidant enzymes), reducing ROS accumulation, and removing denatured proteins. It can also bind to cytoplasmic phosphorylated proteins to regulate antioxidant enzyme activity, induce melatonin production, and upregulate MT expression, thereby improving the ability of cells to tolerate Cd [ 157 , 158 , 159 ], which may be related to the DNA-binding domain in the heat shock transcription factor, HsfA4a [ 160 ]. In addition to the synthesis of HSP, plants can also induce ethylene production under Cd stress.…”