The role of nitric oxide in plant biology:Current insights and future perspectives

Nitric oxide (NO) is a redox-active gaseous signal uniformly present in eukaryotes, but its formation, signalling, and effects are specific within the plant kingdom in several aspects. NO synthesis in algae proceeds by mechanisms similar to that in mammals, but there are different pathways in higher plants. Beyond synthesis, the regulatory processes to maintain steady-state NO levels are also integral for the projection of NO function. As a key redox molecule, NO exhibits a number of pivotal molecular interactions, for example with reactive oxygen species, hydrogen sulfide, and calcium, with these molecular interplays largely underpinning NO bioactivity. In this context, NO has emerged as a key regulator in plant growth, development, and environmental interactions. In this special issue, a collection of reviews discusses the current state-of-the-art and possible future directions related to the biology and chemistry of plant NO function

Cross-talk of nitric oxide and reactive oxygen species in plant programed cell death

In plants, programed cell death (PCD) is an important mechanism to regulate multiple aspects of growth and development, as well as to remove damaged or infected cells during responses to environmental stresses and pathogen attacks. Under biotic and abiotic stresses, plant cells exhibit a rapid synthesis of nitric oxide (NO) and a parallel accumulation of reactive oxygen species (ROS). Frequently, these responses trigger a PCD process leading to an intrinsic execution of plant cells. The accumulating evidence suggests that both NO and ROS play key roles in PCD. These redox active small molecules can trigger cell death either independently or synergistically. Here we summarize the recent progress on the cross-talk of NO and ROS signals in the hypersensitive response (HR), leaf senescence and other kinds of plant PCD caused by diverse cues