Functions of Redox Signaling in Pollen Development and Stress Response

Abstract

Cellular redox homeostasis is crucial for normal plant growth and development. Each developmental stage of plants has a specific redox mode and is maintained by various environmental cues, oxidants, and antioxidants. Reactive oxygen species (ROS) and reactive nitrogen species are the chief oxidants in plant cells and participate in cell signal transduction and redox balance. The production and removal of oxidants are in a dynamic balance, which is necessary for plant growth. Especially during reproductive development, pollen development depends on ROS-mediated tapetal programmed cell death to provide nutrients and other essential substances. The deviation of the redox state in any period will lead to microspore abortion and pollen sterility. Meanwhile, pollens are highly sensitive to environmental stress, in particular to cell oxidative burst due to its peculiar structure and function. In this regard, plants have evolved a series of complex mechanisms to deal with redox imbalance and oxidative stress damage. This review summarizes the functions of the main redox components in different stages of pollen development, and highlights various redox protection mechanisms of pollen in response to environmental stimuli. In continuation, we also discuss the potential applications of plant growth regulators and antioxidants for improving pollen vigor and fertility in sustaining better agriculture practices.

The Balance between Different ROS on Tobacco Stigma during Flowering and Its Role in Pollen Germination

“…Anomalous ROS homeostasis is one of the most important mechanisms of inhibition of sexual plant reproduction, including both reproductive development and fertilization, under high-temperature stress, salt stress and drought [ 26 , 29 , 30 , 31 ]. Thus, comparing the production of various ROS on the stigma of stress-resistant and sensitive wheat varieties, the authors came to the conclusion that in the second case, the production was noticeably increased under conditions of complex stress [ 32 ].…”

Phytohormones and Transcriptome Analyses Revealed the Dynamics Involved in Spikelet Abortion and Inflorescence Development in Rice

“…Plants require different oxidants, ROS, and reactive nitrogen species (RNS) for many growth and development-related processes. Plants maintain the concentration of oxidants by releasing antioxidants in different pathways, as the elevated level of oxidants is also toxic to cellular function, including pollen development [ 56 ]. The reproductive development, especially microsporogenesis and pollen development, are sensitive to the external environment.…”

“…The reproductive development, especially microsporogenesis and pollen development, are sensitive to the external environment. A complex network of ROS and RNS controlling genes regulates the redox homeostasis by inducing PCD in the tapetum for normal inflorescence and pollen development [ 56 ]. Balance in the ROS production and scavenging in a cell is maintained by enzymatic (superoxide dismutase, peroxidase, catalase, etc.)…”

“…Hierarchical clustering revealed the significant downregulation of antioxidant, oxidoreductase, and peroxidase activities, implying the persistence of an imbalanced redox environment in the spikelets of apa1331 . Previous studies have also reported that a decrease in antioxidant activity and an imbalance in redox reactions causes panicle degeneration [ 7 , 56 ], and the tetrapyrrole group has also been reported to be involved in ROS homeostasis, PCD, and photosynthate assimilation [ 58 ]. These studies suggest that spikelet abortion in apa1331 was caused due to imbalance in the redox homeostasis.…”

“…Similarly, P is an essential component of amino acid and carbohydrate metabolisms, and its deficiency is associated with decreased fertility and abortion due to photooxidative damage to the cellular organelles [ 60 ]. Glutathione (GSH), ascorbate (ASA), proline, tocopherol, phenolic acid, carotenoids, and flavonoids are non-enzymatic antioxidants which are suggested to play a role in pollen fertility [ 56 , 61 ]. GSH and ASA regulate the redox status during pollen development [ 61 ].…”