Increasing in ROS levels and callose deposition in peduncle vascular bundles of wheat (Triticum aestivum L.) grown under nitrogen deficiency

Nitrogen availability is closely related to crop senescence and productivity, but its associated effect on reserve remobilization is not yet fully understood. In this study, we observed that nitrogen deficiency (N) led to significant decreases in the activities of superoxide dismutase (SOD) (P<0.05), guaiacol peroxidase (P<0.05), and catalase (P<0.05) as well as a higher concentration of reactive oxygen species (ROS) (P<0.05) in wheat (Triticum aestivum L.) peduncles during the middle grain-filling compared with the application of 225 kg N ha(1) (N+). Callose concentration showed the same trend of temporal changes as ROS. Histochemical staining revealed that both ROS and callose predominantly occurred in vascular bundles of peduncles. Ultimately, grain filling rates and grain weight in N wheat were reduced compared with N+ plant. These data suggest that the grain yield decline in N wheat may be at least partially attributed to the higher callose deposition in peduncle vascular bundles and ROS level is closely associated with the increase in the callose deposition in wheat peduncle vascular bundles.