Disruption of a glycosyl transferase family 17 protein alters cadmium accumulation and resistance in rice (Oryza sativa)

Aims Cadmium (Cd) is absorbed by plants into the food chain as a trace pollutant harmful to humans. The rice (Oryza sativa. L) glycosyltransferases (OsGTs) family is a large protein family with over hundreds of members, however, prior studies have failed to identify which OsGTs has a role in plants' response to Cd toxicity. In this study, we defined the role of OsGT17 in the regulation of grain Cd accumulation in rice. Methods One-week-old Zhonghua 11 (ZH11), osgt17 mutants, and OsGT17 overexpressing lines were treated with or without 1 mu M Cd in solution for 7 days. Roots were then harvested for analysis of Cd as well as for cell wall and RNA extraction, while shoots were collected for Cd analysis. Results OsGT17 was located in the cell wall and displayed constitutive expression, despite its expression and protein accumulation were repressed by Cd. OsGT17 positively regulated Cd resistance in rice, as osgt17 mutants exhibited Cd sensitive phenotype while OsGT17 overexpressing plants exhibited Cd resistant phenotype. Furthermore, we showed that OsGT17 could regulate hemicellulose, especially xyloglucan level in root cell wall, which acted as a Cd compartmentalization sites, thus more Cd was accumulated in osgt17 mutants' root cell wall and root, as a result, high levels of Cd were accumulated in osgt17 mutants' shoots and grains that led them more sensitivity to Cd stress. Conclusions We first identified the role of a specific cell wall associated gene-OsGT17 in decreasing Cd accumulation in rice grains by fixing Cd in the root cell wall.