Reactive oxygen species, nitric oxide and hydrogen sulfide in plant cell regulation

Growth and maintenance of cells is partly controlled by the production and perception of a range of small relatively reactive molecules, including reactive oxygen species, nitric oxide and hydrogen sulfide: what may be dubbed reactive signaling molecules (RSM). These compounds are generated by enzymes or arrive from the cell's environment, often produced in response to cellular stress, including temperature, salt or drought. Regularly studied on an individual basis, such compounds are often in cells at the same time and so interactions between them need to be considered. RSM alter antioxidants in cells, possibly leading to oxidative stress and cell death, perhaps through apoptotic pathways. Gene expression can alter, with the suite of genes regulated being similar for the different RSM. In reality the total cellular response will be the sum of interactions and perception of all RSM. RSM will influence the internal cellular redox poise and compete for thiols, the final modifications of which may determine the response. Lastly, other small molecules with potentially signaling roles need to be considered, e.g. hydrogen gas, which too can influence antioxidant levels in cells. Therefore, a holistic approach needs to be taken to understand the overall cellular response to RSM