Lipid peroxide-derived short-chain aldehydes promote programmed cell death in wheat roots under aluminum stress

Lipid peroxidation is a primary event in plant roots exposed to aluminum (Al) toxicity, which leads to the for-mation of reactive aldehydes. Current evidence demonstrates that the resultant aldehydes are integrated com-ponents of cellular damage in plants. Here, we investigated the roles of aldehydes in mediating Al-induced damage, particularly cell death, using two wheat genotypes with different Al resistances. Aluminum treatment significantly induced cell death, which was accompanied by decreased root activity and cell length. Al-induced cell death displayed granular nuclei and internucleosomal fragmentation of nuclear DNA, suggesting these cells underwent programmed cell death (PCD). During this process, caspase-3-like protease activity was extensively enhanced and showed a significant difference between these two wheat genotypes. Further experiments showed that Al-induced cell death was positively correlated with aldehydes levels. Al-induced representative diagnostic markers for PCD, such as TUNEL-positive nuclei and DNA fragmentation, were further enhanced by the aldehyde donor (E)-2-hexenal, but significantly suppressed by the aldehyde scavenger carnosine. As the crucial execu-tioner of Al-induced PCD, the activity of caspase-3-like protease was further enhanced by (E)-2-hexenal but inhibited by carnosine in wheat roots. These results suggest that reactive aldehydes sourced from lipid peroxi-dation mediate Al-initiated PCD probably through activating caspase-3-like protease in wheat roots.

Automated summary

This study investigates the roles of reactive aldehydes in mediating aluminum-induced cellular damage in plant roots. The results suggest that reactive aldehydes may mediate aluminum-induced programmed cell death (PCD) by activating caspase-3-like protease in wheat roots, further exacerbating cell death.