LAUSR

Abstract Kenaf (Hibiscus cannabinus L.) is an important natural fiber crop with great potential for Cd-polluted soil phytoremediation. However, little is known about the molecular mechanism of Cd tolerance in kenaf. To reveal this potential molecular mechanism, in the present study, kenaf cultivar FH991 was used for physiological and transcriptomic analysis under different concentration of Cd stress. Result should that kenaf exhibited strong Cd absorbance and transport ability. Under 10 mg L−1 Cd stress condition, the Cd content reached 1986.5 and 321.1 mg kg-1 in the root and shoot, respectively. Antioxidant enzyme activities, including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), were investigated. The result showed that enzyme activities increased and then decreased when plants were exposed to 10 and 30 mg L−1 Cd stress, respectively. Transcriptome sequencing generated approximately 35.2 GB of paired-end raw reads and de novo assembled to yield 105,437 unigenes in the root. A total of 3926 differentially expressed unigenes (DEGs) were identified under Cd stress, comprising 1206 upregulated and 2720 downregulated genes. Validation of 15 stress-responsive DEGs was authenticated by using real-time quantitative PCR. Gene ontology (GO) analysis showed that the DEGs were mainly involved in metabolic process, membrane component, and catalytic activity. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis showed that Cd stress caused changes in DEGs that were mainly involved in carbohydrate metabolism, replication and repair, signal transduction, transport and catabolism, and environmental adaptation. Key DEGsand their involved pathways in such as ‘heavy metal transport and detoxification activity’, ‘ROS antioxidant activity’, ‘GAs and MAPK signaling’, ‘carbohydrate and energy metabolism’ processes as well as a wide range of transcription factors were concluded to play vital roles in kenaf Cd tolerance.