The transcriptome properties of reeds under cadmium stress in Liaohe Estuary wetland

Reed contains a naturally-occurring gene resource base to resist cadmium stress. Transcriptome profiling is conducive to cloning the cadmium-tolerance genes in reed. Reed roots under cadmium stress were sampled, and the Illumina HiSeq™ 2500 transcriptome sequencing was performed. A total of 286,439 unigenes were obtained after de novo assembly. There were 22,304 up-regulating differentially expressed unigenes and 15,711 down-regulation. Two-level clustering formed an accurate heatmap to compare between expression fold-change classes and between treatment classes. The gene ontology terms were mainly enriched into biological regulation, metabolic process, response to stimulus, cell component, catalytic activity, proton-transporting two-sector ATPase and binding. Noticeably, the catalytic activity was mainly forwarded to oxidoreductase activity and antioxidant activity. There were obviously-enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, phenylpropanoid biosynthesis, phenylalanine metabolism, ribosome and photosynthesis. Beta-glucosidase EC: 3.2.1.21 was up-regulation in the phenylpropanoid biosynthesis pathway. Up-regulation of phenylpyruvate tautomerase EC: 5.3.2.1 catalyzes the production of 2-hydroxy-3-phenylpropanoate in the phenylalanine metabolism pathway. In the photosynthesis pathway, there was up-regulation of petN, petH, photosystems I/II, LHCA4 and LHCB3. The protein-protein interaction network showed that beta-glucosidase EC: 3.2.1.21 interacted with c129889_g1 and c115092_g3; up-regulation of photosystems II c111052 interacted with c93463_g1 and c121697_g3. Two up-regulating enzymes EC: 3.2.1.21 and EC: 5.3.2.1 may be the candidates to improve cadmium tolerance in reed. The photosynthesis with light-harvesting and electron transport plays important roles in reed cadmium tolerance. The interacting proteins c129889_g1, c115092_g3, c93463_g1 and c121697_g3 are putative to involve in cadmium tolerance. The current study is promising to provide the profile data for cloning these reed genes.