Drought stress alters iron accumulation in Sorghum bicolor seeds

Sorghum (Sorghum bicolor L.) is a cultivated food crop with iron-rich seeds that thrives in semi-arid areas. Although the mechanism of iron transport has been investigated in detail at the molecular level, the effects of drought stress on its regulation remain unclear. We cultivated sorghum in a chamber without (control) and with drought stress to determine iron accumulation in seeds. The drought stress treatment significantly increased the iron content by approximately 2-fold in seeds and decreased it by 0.6-fold in leaves. The results of RNA -sequencing leaves indicated that drought stress impaired the expression of genes involved in photosynthesis. This agreed with the finding that drought stress significantly reduced plant biomass. The expression of genes encoding vacuole iron transporter and ferritin were increased under drought stress. These expression profiles were confirmed by quantitative polymerase chain reaction, which indicated that expression of genes encoding the vacuole iron transporter and ferritin was significantly increased in leaves and seeds under drought stress. Furthermore, photosynthesis impaired by drought stress might trigger a disturbance in iron homeostasis. Therefore, increased vacuolar transporters and ferritin transcription might be important for safely storing excess iron. Our data suggested that maintaining iron homeostasis via vacuole iron transporters and ferritin enhances iron accumulation in seeds under drought stress.

Automated summary

Drought stress increases iron accumulation in sorghum seeds while decreasing it in leaves. It impairs the expression of genes involved in photosynthesis, leading to reduced plant biomass. Under drought stress, genes encoding vacuole iron transporters and ferritin are upregulated.