Abstract
King grass, a hybrid grass between pearl millet and elephant grass, has many excellent characteristics such as high biomass yield, great stress tolerance, and enormous economic and ecological value, which makes it ideal for development of phytoremediation. At present, the physiological and molecular response of king grass to cadmium (Cd) stress is poorly understood. Transcriptome analysis of early response (3 h and 24 h) of king grass leaves and roots to high level Cd (100 µM) has been investigated and has shed light on the molecular mechanism underlying Cd stress response in this hybrid grass. Our comparative transcriptome analysis demonstrated that in combat with Cd stress, king grass roots have activated the glutathione metabolism pathway by up-regulating glutathione S-transferases (GSTs) which are a multifunctional family of phase II enzymes that detoxify a variety of environmental chemicals, reactive intermediates, and secondary products of oxidative damages. In roots, early inductions of phenylpropanoid biosynthesis and phenylalanine metabolism pathways were observed to be enriched in differentially expressed genes (DEGs). Meanwhile, oxidoreductase activities were significantly enriched in the first 3 h to bestow the plant cells with resistance to oxidative stress. We also found that transporter activities and jasmonic acid (JA)-signaling might be activated by Cd in king grass. Our study provided the first-hand information on genome-wide transcriptome profiling of king grass and novel insights on phytoremediation.
Highlights
Cadmium (Cd) is one of the most hazardous heavy metal pollutants that is massively released from human activities which can induce amounts of reactive oxygen species (ROSs) and have negative effects on protein, nucleic acids, gene expressions, and some essential enzymatic activities causing toxicity and mutagenesis in cells [1]
Our comparative transcriptome analysis elucidated the molecular mechanisms of early responses to Cd stress in king grass providing novel perspectives into phytoremediation investigation
The most dramatic change of Cd content occurred at T3 after Cd treatment with the increase of 165 times in roots
Summary
Cadmium (Cd) is one of the most hazardous heavy metal pollutants that is massively released from human activities which can induce amounts of reactive oxygen species (ROSs) and have negative effects on protein, nucleic acids, gene expressions, and some essential enzymatic activities causing toxicity and mutagenesis in cells [1]. King grass is mainly planted in the Yangzi River basin and south of the Huaihe River in China and other tropical and subtropical regions globally [8] Plus, this hybrid grass has high biomass yield, broad ecological merits, and enormous economic values, which makes it ideal to be developed for phytoremediation. We have already accumulated some knowledge about the molecular mechanisms underlying heavy metal absorption, transportation, and relocation in herbaceous model plant species In both Brassica napus and its close relative Arabidopsis, besides the well-known mechanism that phytochelatins (PCs) and glutathiones (GSHs) can bind to Cd to form Cd-ligands and be shut off in vacuoles serving as a detoxification tool, it is proposed that PCs and GSHs function as long distance carriers between roots and shoots [9]. Our comparative transcriptome analysis elucidated the molecular mechanisms of early responses to Cd stress in king grass providing novel perspectives into phytoremediation investigation
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