Comparative transcriptome analysis of the hyperaccumulator plant Phytolacca americana in response to cadmium stress

Abstract

To study the molecular mechanism of the hyperaccumulator plant Phytolacca americana against cadmium (Cd) stress, the leaves of P. americana treated with 400 μM Cd for 0, 2, 12, and 24 h were harvested for comparative transcriptome analysis. In total, 110.07 Gb of clean data were obtained, and 63,957 unigenes were acquired after being assembled. Due to the lack of P. americana genome information, only 24,517 unigenes were annotated by public databases. After Cd treatment, 5054 differentially expressed genes (DEGs) were identified. KEGG pathway enrichment analysis of DEGs showed that genes involved in the flavonoid biosynthesis and antenna proteins of photosynthesis were significantly down-regulated, while genes related to the lignin biosynthesis pathway were remarkably up-regulated, indicating that P. americana could synthesize more lignin to cope with Cd stress. Moreover, genes related to heavy metal accumulation, sulfur metabolism and glutathione metabolism were also significantly up-regulated. The gene expression pattern of several key genes related to distinct metabolic pathways was verified by qRT-PCR. The results indicated that the immobilization of lignin in cell wall, chelation, vacuolar compartmentalization, as well as the increase of thiol compounds content may be the important mechanisms of Cd detoxification in hyperaccumulator plant P. americana. Accession numbers: the raw data of P. americana transcriptome presented in this study are openly available in NCBI SRA database, under the BioProject of PRJNA649785.

Unraveling Cadmium Toxicity in Trifolium repens L. Seedling: Insight into Regulatory Mechanisms Using Comparative Transcriptomics Combined with Physiological Analyses

“…In our study, the photosynthesis parameters (chlorophyll and chlorophyll a/b) decreased after 3 h of Cd treatment and resumes after 12 h. Except for the chlorophyll, the other two parameters continued to decrease after 72 h, which was also found in soybean plants [81] and S. sclarea [42]. The expression level of chlorophyll photosynthesis-related genes was down-regulated after 3 h Cd treatment and began to resume after 12 h. In the study of Brassica juncea [82] and P. americana [67], the expression level of photosynthesis-related genes decreased rapidly after 12 h of Cd treatment and began to restore after 48 h. The shorter time of this change in T. repens may be due to the high concentration of cadmium treated in this study. Taken together, our study contributes to the understanding of the molecular response mechanism in T. repens under high concentration Cd stress (Figure 8).…”

“…In the glutathione metabolism, the DEGs related to GST were up-regulated in the roots of T. repens, which have unique functions in Cd detoxification [65]. The expression levels of GST genes were also up-regulated in O. sativa [66], Nicotiana species [35], and P. americana [67]. GST was able to catalyze GSH to be conjugated with ROS to protect plant cells from oxidative damage [68].…”

“…The heavy metal ion transporters located on the plant membranes and the tonoplast take an important role in the transport and uptake of Cd [67]. The ABC transport family mainly (PDR, MDR, and MRP) is located in the tonoplast and can transport Cd conjugated complexes as Cd pumps [27,37].…”

Zinc oxide nanoparticles improve lettuce (Lactuca sativa L.) plant tolerance to cadmium by stimulating antioxidant defense, enhancing lignin content and reducing the metal accumulation and translocation

“…The samples were dried in an oven at -80°C until they reached a constant weight, and then their dry weight was determined. Leaf REC was measured using the method reported by Zhou (Zhou et al, 2013). Chlorophyll content was measured by 80% acetone extraction after 14 days of lettuce growth (Tang et al, 2021); root activity was analyzed using the triphenyltetrazolium chloride (TTC) method (Zhang et al, 2013).…”

Comparative root transcriptome analysis of two soybean cultivars with different cadmium sensitivities reveals the underlying tolerance mechanisms

“…NRAMP metal transporters have been reported to transport Cd 2+ and other heavy metal divalent cations, such as Mn 2+ , Zn 2+ , Cu 2+ , Fe 2+ , Ni 2+ , and Co 2+ (Nevo and Nelson 2006;Zhang et al 2021). NRAMP transporters are expressed in roots and shoots and are involved in the transportation of metal ions through the plasma membrane and tonoplast (Krämer et al 2007;Zhao et al 2021). In Arabidopsis, NRAMPs are thought to transport Fe 2+ and Cd 2+ (Thomine et al 2000).…”