Nitric Oxide Alleviates Submergence-Induced Maize Seedling Root Tip Cell Death

Submergence results in submergence-induced hypoxia in plants. Hypoxia sensing and signaling in the root, as a main organ sensing hypoxic stress, play critical roles in plant recovery and survival from submergence. Nitric oxide (NO) is an essential gas signaling molecule involved in the hypoxia signaling pathway. However, how NO affects plant roots in response to hypoxia remains unclear. Here, using sodium nitroprusside (SNP) as an NO donor, we found that pretreatment with SNP enhanced maize seedling hypoxia tolerance under submergence conditions by increasing the cytosolic Ca2+ concentration and alcohol dehydrogenase (ADH) activities in maize root tips. Additionally, a higher antioxidant system capacity, including lower reactive oxygen species (ROS) accumulation and higher related key enzyme activities, was detected, as expected, under NO application conditions. Moreover, with SNP pretreatment, upregulation of hypoxia-responsive gene expression in maize seedling root tips refers to its higher survival rates under hypoxic stress. Overall, we conclude that NO regulates maize roots responding to hypoxia via substance metabolism changes and upregulating hypoxia-responsive gene expression.

Automated summary

The study found that pretreatment with the NO donor SNP enhanced hypoxia tolerance in maize seedlings by increasing Ca2+ concentration and ADH activities in the roots. It also resulted in a higher antioxidant system capacity and upregulation of hypoxia-responsive gene expression. Overall, NO was found to regulate the response of maize roots to hypoxia.