Hydrogen also has a lot of effects on plants, among which Nanjing Agricultural University is the one with more research. In addition, Gansu Agricultural University and other institutions also have relevant research. This study is a recent research paper published by Gansu Agricultural University. It is explained that hydrogen regulation of adventitious root growth may be realized by another important plant hormone ethylene.
Studies have shown that both hydrogen and ethylene play a key role in adventitious roots. However, in this process, the relationship between hydrogen and ethylene has not been explored and fully understood. In this study, cucumber seedlings were used as materials to study the proteomic changes in the process of induced rooting. The results showed that ethylene releasing compound (Ethrel) promoted exogenous oil adding at appropriate concentration, and the maximum biological reaction of hydrogen rich water occurred at 50% or 0.5? M Ethrel. AVG and AgNO3, inhibitors of ethylene, partially inhibited the hydrogen induced adventitious roots, suggesting that ethylene may be involved in the process of hydrogen induced adventitious roots. Two dimensional electrophoresis and mass spectrometry analysis showed that 9 proteins were up-regulated and 15 proteins were down regulated in hydrogen rich water treatment; 4 proteins were up regulated and 10 proteins were down regulated in ethephon treatment; 1 protein was up regulated and 9 proteins were down regulated in hydrogen rich water + AVG treatment.
Further analysis of these differential proteins revealed that they included photosynthesis related protein, ribulose diphosphate carboxylase, oxygen evolution enhancing protein, amino acid metabolism related protein threonine dehydratase, pressure response related protein, cytoplasmic ascorbate peroxidase, and folding, modifying and degrading related proteins. The results show that ethylene may be a downstream signal molecule in the process of hydrogen induced adventitious roots, and a variety of important functional proteins may play an important role in this process.
Adventitious roots are formed by non root tissues such as leaves, stems and hypocotyls. Adventitious roots can increase the area of roots, improve their ability to absorb nutrients and support plants. Adventitious roots play an important role in promoting the asexual propagation of fine varieties and the development of agriculture and forestry industry. Therefore, it is necessary and significant to explore the mechanism of adventitious root formation. The role of signal molecules in adventitious root development has been a hot topic in recent years. Further study of signal transduction will help us to understand the mechanism of adventitious roots.
Ethylene is a simple bicarbonate molecule, which plays an important role in regulating plant growth and development. Ethylene may induce a variety of effects in the whole plant life cycle, including seed germination, flower senescence and fruit ripening. Ethylene also participates in plant defense response to pathogen or elicitor attack, as well as response to abiotic stress, such as trauma, hypoxia, cold, freezing, indicating that ethylene may be a regulator of plant growth, development and stress response.
Since the first discovery of ethylene stimulated adventitious root formation, there have been a lot of achievements in this field. Hydrogen (hydrogen) is the lightest gas. It is a colorless, odorless and tasteless diatomic gas. Ohsawa et al. (2007) found that hydrogen can be used as an effective antioxidant for cerebral ischemia in rats. Since then, the application of hydrogen in the prevention and control of various diseases has become a research hotspot. In recent years, the physiological function of hydrogen in higher plants has also been studied. Hydrogen is often shown to respond to salt stress, drought stress, heavy metal toxicity, oxidative stress and UV-A irradiation, inducing stomatal closure. Recently, another function of hydrogen has been found: to promote the occurrence of adventitious roots. Lin et al. (2014) showed that 50% hydrogen rich water can simulate heme function and restore the formation of adventitious roots of Cucumber by regulating the expression of auxin signal related genes and adventitious root related genes. Zhu et al. (2016) reported that hydrogen rich water treatment increased the content of nitric oxide (no) during adventitious root formation and up regulated cell cycle activation. In addition, Cao et al. (2017) believed that hydrogen rich water participated in auxin induced lateral root formation by regulating NO synthesis dependent on Nr.
Ethylene and hydrogen are involved in the formation of adventitious roots. However, the exact mechanism remains unclear. In this study, we hypothesized that there was a certain relationship between ethylene and hydrogen in the adventitious roots of cucumber.
To prove this hypothesis, ethylene inhibitors were used. Proteomic methods have been widely used to determine genetic and cellular functions at the protein level. Proteomic analysis has also been shown to be useful in identifying proteins associated with a range of biological and abiotic stress responses. We used 2-DE and matrix assisted laser desorption ionization ion source and time of flight mass analyzer (maldi-toftoftof) to compare the quantitative and qualitative changes in the process of ethylene and hydrogen induced proteome rooting. Through the comprehensive analysis of the function and content of different proteins and the expression of genes related to these proteins, it is speculated that ethylene may affect the expression of some proteins and related genes. These results provide new insights into the physiological and molecular mechanisms of adventitious roots.
The results showed that both hydrogen and ethylene played an important role in promoting adventitious root development. Ethylene may be a downstream signal molecule in the process of hydrogen induced rooting. Further proteomic studies have shown that photosynthesis related proteins, amino acids and metabolism related proteins, stress response related proteins and folding, modifying and degradation related proteins may play an active role in the ethylene mediated adventitious root process. Oxygen evolution enhancer protein may play an inhibitory role in this process. The mechanism of adventitious roots is very complex, and more research is needed to fully understand the signal of adventitious roots.
Some research results
Effects of different concentrations of hydrogen rich water and Ethrel on adventitious root development
In order to understand the effects of different concentrations of hydrogen rich water (0,1%, 10%, 50% and 100%) on the development of Cucumber in vitro. As shown in Figure 1, different concentrations of hydrogen rich water affect the development of adventitious roots. 50% and 100% hydrogen rich water treatments produced more adventitious roots than the control, but 1% hydrogen rich water treatment produced significantly fewer roots than the control. The maximum number of elements can be observed in 50% hydrogen rich water treatment (Fig. 1) and used for further study.
Figure 1: effect of different concentration of hydrogen rich water on adventitious root development. Effects of ethylene inhibitors AVG and AgNO on hydrogen induced adventitious root development
In order to further study the role of ethylene in adventitious root formation, we used ethylene inhibitors. The results are shown in the figure. S4 and S5 showed that AVG and AgNO3 had negative effects on rooting. We used 1? Mol / L AVG and 0.1? Mol / L silver nitrate for further study. As can be seen from Fig. 3, the adventitious roots of explants treated with hydrogen rich water or ethephon alone were improved compared with the control. The number of explants treated with hydrogen rich water and ethephon was higher, but there was no significant difference compared with the explants treated with hydrogen rich water or ethephon alone. When AVG (ethylene synthesis inhibitor) or AgNO3 (ethylene action inhibitor) were added to hydrogen rich water, the induction of adventitious roots was reversed by ethylene (Fig. 3), so it was concluded that ethylene may participate in the development of hydrogen induced adventitious roots.
Figure 3: effect of ethylene inhibitors on H - induction of adventitious root development. The effect of hydrogen on the production of ether and the expression of ether related genes
As shown in Figure 4a, the ethylene production of 50% hydrogen rich water treatment is about twice that of the control. In addition, the results of Fig. 4B showed that hydrogen rich water treatment significantly increased the gene expression of csacs3. Compared with the control group, hydrogen rich water significantly increased the expression of CSA CO1. These consistent results suggest that ethylene may play a role downstream of hydrogen induced adventitious root formation.
Figure 4: effects of hydrogen rich water on ethylene production (a) and expression levels of two ethylene related genes (b) in Cucumber explants.