| In potted and greenhouse conditions, using trifoliate orange(Poncirus trifoliate) seedings as material, we researched the effects of peroxide hydrogen and arbuscular mycorrhizal on the mycorrhizal development, root architecture and metabolized enzymes activity of polyamines (ADC, ODC, PAO, and DAO). In order to analysis the relation of peroxide hydrogen, mycorrhizal and root architecture.Trifoliate orange (Poncirus trifoliata) seedlings grows in the substrate inoculated arbuscular mycorrhizal fungi(Glomus versiforme), the seedings were dealt with different concentrations of hydrogen peroxide after four weeks, and observed the growth of the arbuscular mycorrhizal status after processing nine weeks. The results showed, the mycorrhizal colonization, vesicle and entry point dealt with low concentration of hydrogen peroxide were higher than the high concentration of hydrogen peroxide and no hydrogen peroxide treatment, at the same time, the treatment with high concentration of hydrogen peroxide of the seeding mycorrhizal colonization and vesicle was lower than the no hydrogen peroxide treatment. On the one hand, the development of arbuscular mycorrhizal was influenced by the host plant nutrition levels, namely, the distribution of carbon source, on the other hand, the external factors might affect the growth of mycorrhizal, such as hormone, external factors is likely to stimulate the development of mycorrhizal, but also could inhibit it. Like this experiment, the low concentration of exogenous H2O2acted the signal molecular, stimulated the development of mycorrhizal, significantly improved the mycorrhiza infection of trifoliate orange(Poncirus trifoliata) seedlings, but the high concentration of H2O2played the role of inhibition and hindered the development of mycorrhiza, suppressed the mycorrhizal infection.Plant roots become the good material to study the plant developmental plasticity, due to its relatively simple structure and extremely complex configurations. The root system configuration changes under the influence of non-biological and biological factors, such as the plant itself, the distribution of the carbon source, climate environment, soil physical and chemical properties, exotic hormone stimulation and soil microorganisms and human activities will affect it. At present, the study of root morphology are mainly concentrated in hormone, and the study of the effect of hydrogen peroxide and soil microbes, arbuscular mycorrhizal fungi in the role of root growth and development process is less studied. In this experiment, inoculation of arbuscular mycorrhizal fungi has significantly increased the root length, surface area, projection area, volume and number of lateral root, compared with non-inoculation plant root. However, the trifoliate orange (Poncirus trifoliata) seedlings root configuration parameters dealt with hydrogen peroxide(1,100μmol/L), except root length, the rest of the parameters were less than no hydrogen peroxide treatment (0μmol/L) in the root inoculated with arbuscular mycorrhizal fungi. It was found that arbuscular mycorrhizal fungi has no interaction with hydrogen peroxide through statistical analysis, it suggests that arbuscular mycorrhizal fungi has antagonism effect with hydrogen peroxide in improving root conformation, the higher the concentration of hydrogen peroxide, the more obvious this effect might be.Arbuscular mycorrhizal fungi is a kind of heterotrophic type fungi, it needs to access pentose from the host plant to sustain their own lives. In this experiment, the root sucrose and glucose contents of trifoliate orange (Poncirus trifoliata) seedlings was significantly higher in the leaf after inoculated arbuscular mycorrhizal fungi and hydrogen peroxide treatment without non-inoculated arbuscular mycorrhizal fungi, the root sucrose and glucose allocation rate were higher than the control; After inoculation, the trifoliate orange (Poncirus trifoliata) seedlings root sugar allocation rate with hydrogen peroxide treatment was higher than contrast and with no hydrogen peroxide treatment, the association of inoculation with hydrogen peroxide promoted the increased of the root glucose content, and the effect of low concentration of hydrogen peroxide(1μmol/L) was more obvious. These indicated that hydrogen peroxide and arbuscular mycorrhizal fungi on plant root sugar content distribution value has a significant role in promoting, let root system obtain more carbon source to builting root architecture.Alone with hydrogen peroxide treatment and inoculated arbuscular mycorrhizal fungi all can effectively improve the leaf and root arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) activity, and inoculation treatment increased the leaf and root polyamine oxidase (PAO) and diamine oxidase (DAO) enzyme activity. For mycorrhization seedings after hydrogen peroxide treatment, leaf and root arginine decarboxylase (ADC) was significantly higher than control and only inoculated seedings, and the leaves and roots polyamine oxidase(PAO) and diamine oxidase (DAO) activity was lower than the inoculation treatment. The center product of polyamine biosynthesis is putrescine, it can be synthesised with two ways of arginine and ornithine under the action of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC), and then converted into spermine and spermine, so as to promote the synthesis of polyamine in plants, and then polyamine degradation by the two ways of polyamine oxidase (PAO) and diamine oxidase (DAO), which regulates the level of polyamines. That is to say, the inoculation of arbuscular mycorrhizal fungi play a positive role for polyamine synthesis and degradation, this role made plant polyamine metabolism in the body become more active, and the synthesis and degradation is still in a dynamic balance. Hydrogen peroxide and arbuscular mycorrhizal fungi coprocessing could promoted the synthesis of polyamine, but clearly showed inhibitory effect on the degradation of polyamine, which made the polyamine content in the plant rapid increased, many researches have confirmed that the reducce of polyamines synthesis level can inhibit the growth of roots, the improvement of polyamine synthesis increases the root cell division to promote the growth of root elongation.In conclusion, changes in plant root architecture affected by a variety of internal and external factors. In this experiment, the hydrogen peroxide and arbuscular mycorrhizal fungi treatment significantly improved the distribution rate of root sucrose and glucose, let roots have sufficient carbon source as the root architecture reconstruction of energy, the new root system make roots got more and more broad growth space, water and nutrient source; Similarly, the increase of polyamine synthesis also played an important regulatory role in changing the root architecture. |
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