Genome-wide analysis of metallothionein gene family in maize to reveal its role in development and stress resistance to heavy metal

Abstract

Background Maize (Zea mays L.) is a widely cultivated cereal and has been used as an optimum heavy metal phytoremediation crop. Metallothionein (MT) proteins are small, cysteine-rich, proteins that play important roles in plant growth and development, and the regulation of stress response to heavy metals. However, the MT genes for maize have not been fully analyzed so far. Methods The putative ZmMT genes were identified by HMMER.The heat map of ZmMT genes spatial expression analysis was generated by using R with the log2 (FPKM + 1).The expression profiles of ZmMT genes under three kinds of heavy metal stresses were quantified by using qRT-PCR. The metallothionein proteins was aligned using MAFFT and phylogenetic analysis were constructed by ClustalX 2.1. The protein theoretical molecular weight and pI, subcellular localization, TFs binding sites, were predicted using ProtParam, PSORT, PlantTFDB, respectively. Results A total of 9 ZmMT genes were identified in the whole genome of maize. The results showed that eight of the nine ZmMT proteins contained one highly conserved metallothio_2 domain, while ZmMT4 contained a Metallothio_PEC domain. All the ZmMT proteins could be classified into three major groups and located on five chromosomes. The ZmMT promoters contain a large number of hormone regulatory elements and hormone-related transcription factor binding sites. The ZmMT genes exhibited spatiotemporal specific expression patterns in 23 tissues of maize development stages and showed the different expression patterns in response to Cu, Cd, and Pb heavy metal stresses. Conclusions We identified the 9 ZmMT genes, and explored their conserved motif, tissue expression patterns, evolutionary relationship. The expression profiles of ZmMT genes under three kinds of heavy metal stresses (Cu, Cd, Pb) were analyzed. In summary, the expression of ZmMTs have poteintial to be regulated by hormones. The specific expression of ZmMTs in different tissues of maize and the response to different heavy metal stresses are revealed that the role of MT in plant growth and development, and stress resistance to heavy metals.

Effects of Free Amino Acids, Metallothionein, and Chemical Forms of Heavy Metals on the Accumulation and Detoxification of Cadmium and Chromium in Chinese Goldthread (Coptis chinensis Franch.)

“…Moreover, CcMT2 exhibited different response patterns to heavy metal stress in different plant tissues. This result is consistent with that observed in maize, indicating that plants have different regulatory mechanisms for different heavy metal stresses [23] (Saccharum sinensis Roxb.) has been shown to upregulate the expression of MT genes that confer Cr tolerance [74], and this high expression of MT genes is consistent with the high heavy tolerance reported in Oryza sativa L. [8], Sedum alfredii Hance [75], and S. lycopersicum [71].…”

“…Amino acids bind to various metal ions through their chelating moieties, including amino (-NH 2) , carboxylic (-COOH), hydroxyl (-OH), and thiol (-SH) groups, all of which have charge donating and complex stabilizing abilities [22]. Notably, amino acids are essential for the synthesis of glutathione (GSH) and phytochelatins (PCs), which are effective heavy metal chelation ligands in plant cells [23]. Chemical forms of heavy metals play important roles in the internal mechanisms of plants that impart protection against heavy metal toxicity [24].…”

Changes in physio-biochemical parameters and expression of metallothioneins in Avena sativa L. in response to drought

“…Regulatory elements play a crucial role in plant responses to various stresses, including drought stress 74 . There are not many studies comparing promoters of different types of MTs in one plant species 64 , 65 , 72 . Our analyses of oat metallothionein promoters revealed the presence of several cis -acting elements involved in response to light, phytohormones, biotic and abiotic stress, and plant development (Fig.…”

Phytoremediation technologies and their mechanism for removal of heavy metal from contaminated soil: An approach for a sustainable environment

“…Maize is established as a heavy metal accumulator; however, the detailed molecular mechanism is not amply known. The expression of the ZmMTs gene under heavy metal stresses (Cu, Cd, and Pb) regulated by the hormones and MT synthesis improves the growth and development of the maize plants (Gao et al, 2022). Jin et al (2022) investigated the role of the PC synthase gene ZmPCS1 of maize in Cd stress.…”