Transgenic tobacco plants with additional enzymes producing hydrogen peroxide (H₂O₂)—superoxide dismutase from Arabisopsis thaliana and choline oxidase from Arthrobacter globiformis—have increased resistance to stress factors, which was demonstrated previously, but their reproductive potential has not been studied to date. Superoxide dismutase converts superoxide radical into H₂O₂, and choline oxidase catalyzes the oxidation reaction of choline to form betaine aldehyde, which is subsequently converted into glycine betaine and H₂O₂. We found that the addition of both exogenous genes stimulated growth of the floral organs: petals, styles, and stamens. However, the reproductive potential of the transgenic plants was different. Thus, the introduction of the superoxide dismutase gene FeSOD significantly increased pollen germination in vitro, in vivo, the size of fruits, and the number of seeds. At the same time, the insertion of the CodA gene resulted in the production of abnormal pollen with low germination in vitro. The female reproductive potential system in these plants was not affected. Thus, shifting the ROS balance towards hydrogen peroxide not only increases tobacco stress resistance but also stimulates reproductive success. Glycine betaine production disrupts pollen formation, although such plants show increased resistance to osmotic stress.

Pollen–stigma interactions have been studied extensively because they play an important role in sexual reproduction and crop yield. The vast majority of studies have focused on dry stigmas, which are typical of many model and agricultural plants; however, the data obtained are difficult to apply to plants with wet stigmas, such as tomato and tobacco. Pollen germination in this case occurs in a liquid, an exudate, which has a complex, species-specific composition. UPLC-ESI-MS-based hormone screening was carried out for six plant genera belonging to Solanaceae, Bromeliaceae, and Gesneriaceae families and revealed jasmonic acid (JA), abscisic acid (ABA) and/or jasmonoyl-L-isoleucine (IleJA) in stigma exudates of tobacco, tomato, and Streptocarpus sp. To assess the physiological significance of plant hormones in stigma exudate we tested their effect in vitro, finding that JA, IleJA, and MeJa significantly stimulated germination of tobacco pollen, with JA being most effective in accordance with its predominance in the stigma exudate; furthermore, ABA stimulated pollen germination in all tested species including bromeliads despite the lack of this hormone in their exudates. Both JA and ABA had an anti-oxidant effect on germinating pollen. Possible functions of hormones and ROS in exudate as well as ways of implementing the anti-oxidant effect of phytohormones are discussed.

Nicotiana tabacum is a classic model for studying pollination on wet stigma. Reactive oxygen species (ROS) and nitric oxide (NO) production are closely related to stigma fertility and depend on the activity of redox enzymes. This study is devoted to the comparison of two tobacco lines differing in physiological parameters and reproductive success. Samsun is a tobacco variety that is widely used in research due to its low demands; however, the reproductive potential of the variety is quite low. Based on this variety, a new line was obtained, called “Fortune”; the plants are externally similar to the Samsun plants, but are more successful in reproduction. The total production of ROS + NO on the stigmas of the Fortune plants is lower than the Samsun plants, but their ROS production is higher, and the main decrease occurs due to NO. Superoxide dismutase activity differs between the two lines at all stages of stigma development except the fertile stage, while ascorbate peroxidase activity is higher in “Fortune” at all stages. Additional isoforms of ascorbate peroxidase are detected in developing stigmas of the Fortune variety. Presumably due to differences in redox metabolism, Fortune plants produce more seeds, their fruit are larger, and their leaves and flowers are also larger compared to the Samsun plants. In this study, we investigated both redox homeostasis parameters and plant productivity using tobacco as the model plant and suggested that there is a correlation between these groups of parameters, which may be important for breeding highly productive plants.

Tobacco is a plant with a wet stigma, which produces reactive oxygen species (ROS) and abscisic acid (ABA) which is important for in vivo pollen germination. Furthermore, ROS can be linked to growth processes, stimulating or inhibiting them. However, to what extent do differences in the redox environment and ABA level on the stigma and in pistil tissues correlate with flower growth, pollination success and resulting fruit parameters? We investigated redox homeostasis and ABA concentrations in stigma exudates of two tobacco lines (“Samsun” and “Fortune”) with different floral organ size and seed production. Fortune has longer flowers, larger fruits, and more seeds than Samsun. We report here that Samsun has a higher total oxidative capacity in stigma exudate, and possibly also higher NO level, than Fortune, as estimated by electron paramagnetic resonance spectroscopy. Fortune has a higher ascorbate peroxidase (APX) content in stigma tissues, as determined by Western blot analysis, and a higher ABA concentration in stigma exudate. Analyzing ROS levels and enzyme activity during the elongation stage in buds, we found that shorter Samsun styles had higher ROS levels, but they also had higher superoxide dismutase (SOD) and APX activity. The results of this study may help in developing approaches to a targeted increase in flower size and seed productivity.