Transcriptomic and physiological comparsion of the short-term responses of two Oryza sativa L. varieties to cadmium

Though responses to Cd in rice (Oryza sativa L.) have been well established, there are few reports about the different effects of short-term exposure to Cd between the subspecies indica (‘Kasalath’ variety) and japonica (‘Nipponbare’ variety). We observed similar Cd accumulation and root damage in roots of two varieties under 6 h Cd stress, but KEGG pathway analysis of transcriptome data revealed that pathways involved in different metabolic processes were affected. Among them, antioxidant enzyme system was involved in Cd detoxification in ‘Nipponbare’ variety, whereas GSH metabolism played important roles in ‘Kasalath’ variety. From the results of physiological experiments, extremely higher activity of SOD, POD, and CAT was observed in ‘Nipponbare’ variety after a short-term exposure to Cd. At the same time, the immediate Cd-induced stimulation of Cys and PCs were observed in ‘Kasalath’ variety along with the enlargement of vacuoles. This study provides an overview of main responses to short-term Cd stress and identifies potential target genes that may contribute to the different mechanisms of Cd stress-resistance in roots of japonica subspecies and indica subspecies.