The effects of different pharmacological agent treatments on ROS accumulation and functional protein activities in wheat endosperm PCD

Wheat (Triticum aestivum L.) is one of the top three food crops in the world. Studies have revealed that wheat endosperm development undergoes programmed cell death (PCD) process development that may be influenced by PCD. Waterlogging and exogenous hydrogen peroxide (H₂O₂) treatment exacerbates wheat endosperm PCD, whereas PCD acceleration is significantly inhibited by reactive oxygen species (ROS) scavengers. To explore the physiological mechanism of waterlogging resistance in wheat, the effects of exogenous H₂O₂, ascorbic acid (AsA), and cyclosporin A (CsA) treatment on ROS content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity in the endosperm of Huamai 8 (waterlogging-tolerant wheat cultivar) and Huamai 9 (waterlogging-sensitive wheat cultivar) were studied. The results showed that exogenous H₂O₂ treatment resulted in an increase in ROS content, antioxidant enzyme activity, mitochondrial membrane permeability, release of cytochrome c, and caspase-like protease activity in the endosperms of both wheat cultivars, which eventually exacerbated PCD. Compared to Huamai 8, the increase in ROS content in Huamai 9 was more significant, whereas changes in antioxidant enzyme activity, cytochrome c release, mitochondrial membrane permeability, and caspase-like protease activity were smaller. Exogenous AsA treatment leads to the content of H₂O₂ and catalase activity decrease, which could inhibit endosperm cell death to some extent. CsA treatment effectively inhibited the increase in H₂O₂ content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity caused by exogenous H₂O₂ treatment, which in turn inhibited cell death. In summary, exogenous H₂O₂ treatment aggravates endosperm PCD, and Huamai 9 exhibited higher ROS accumulation and a weaker antioxidant enzyme system under external stress, which may be the mechanisms underlying its sensitivity to waterlogging. CsA effectively inhibited the increase in ROS, antioxidant enzyme activity, cytochrome c release, and cell death. It is possible that in wheat endosperm, mitochondria in a similar way to animal mitochondria release cytochrome c regulating PCD.