ROS and Ions in Cell Signaling during Sexual Plant Reproduction

Abstract

Pollen grain is a unique haploid organism characterized by two key physiological processes: activation of metabolism upon exiting dormancy and polar tube growth. In gymnosperms and flowering plants, these processes occur in different time frames and exhibit important features; identification of similarities and differences is still in the active phase. In angiosperms, the growth of male gametophyte is directed and controlled by its microenvironment, while in gymnosperms it is relatively autonomous. Recent reviews have detailed aspects of interaction between angiosperm female tissues and pollen such as interactions between peptides and their receptors; however, accumulated evidence suggests low-molecular communication, in particular, through ion exchange and ROS production, equally important for polar growth as well as for pollen germination. Recently, it became clear that ROS and ionic currents form a single regulatory module, since ROS production and the activity of ion transport systems are closely interrelated and form a feedback loop.

Links between Regulatory Systems of ROS and Carbohydrates in Reproductive Development

“…Scission of polysaccharides via the function of OH− results in loosing of pollen wall, probably leading to the acceleration of pollen hydration [ 69 ]. In contrast, H 2 O 2 strengthens polymers via peroxidase-mediated cross-linking of hydroxycinnamates [ 44 , 70 ]. In Arabidopsis, KINβγ is known as a subunit of SUCROSE NON-FERMENTING 1-RELATED PROTEIN KINASE 1 (SnRK1) complex that is essential for maintenance of the functions of the mitochondria and peroxisomes [ 71 ].…”

“…High accumulation of ROS in the stigma prior to the pollen attachment was proposed to be essential for pollen–pistil interaction, as well as defense mechanisms against microbe attack [ 17 , 44 , 75 ]. Decreased level of ROS in the stigma by the exogenous application of flavonoids inhibited the attachment of pollen to the stigma [ 76 ], suggesting the significance of high level of ROS accumulation in the stigma for pollen adhesion.…”

“…However, we do not cover all aspects of regulatory systems of ROS and carbohydrates that function in reproductive tissues. For more details on the mechanisms underlying reproductive development, we would like to refer our readers to more extensive reviews (see [ 3 , 4 , 41 , 42 , 43 , 44 ]).…”

Pollen Germination and Pollen Tube Growth in Gymnosperms

“…Redox homeostasis is one of the main regulatory systems during pollen germination and tube growth in flowering plants, and it has been actively studied in recent years, especially regarding pollination and pollen behavior in vivo [ 89 , 90 , 91 , 92 ]. However, much less is known about the role of this system in gymnosperms [ 89 ]. For example, ROS can affect the germination pattern in Picea pungens , altering rigidity of the cell wall and its resistance to rupture [ 31 ].…”

Cell Signaling in Model Plants 2.0

“…ROS are a universal regulatory element in plant cells and participate in an array of signaling pathways. Breygina and Klimenko reviewed the role of ROS and the underlying mechanism involving ion transport systems during plant sexual reproduction [ 17 ]. They found that ROS are involved at most stages of the life cycle in the male gametophyte, and it chiefly acts through ion currents by a feedback loop.…”