| Al toxicity is a major limiting factor limited crop production in acid soils. Acidic soil in the world accounts for about 40% of global arable soil area and China's acidic soil accounts for more than 21% of the area. Therefore, fertilization management of acidic soil for sustainable development of the agricultural economy has a very important role.The most obvious feature of Al toxicity to plants is the inhibition of root growth and the influence of root absorption of water and nutrients. Nitrate is one of the main mineral forms of nitrogen uptaken by plant. Nitrate nitrogen in upland soil for early crop plays an important role, and the correlation between Nitrate nitrogen in upland soil and plant nitrogen uptake reaches a significant level. Previous studies showed that the nitrate uptake rate of crop decreased under Al stress, the effect of Al on the NO3-uptake is greater compared to NH4+.In addition, Al stress also affects photosynthesis, water use efficiency and nitrogen metabolism in aboveground plant, resulting in reduction of the biomass. However, the mechanism of Al stress on plant roots absorbing nitrate and photosynthesis is unclear. In this study, we taken Tamba black Al-tolerant soybean (RB) imported from Japan and Yunnan locally Al-sensitive black soybean (SB) as experimental materials, by adding a series of Al concentrations in modified Hoagland nutrient solution to treat RB and SB, analysis the correlation among NO3-uptake and photosynthesis of two soybeans, the contents of roots and leaves, plasma membrane H+-ATP ase phosphorylation and its interaction with 14-3-3 proteins, plasma membrane H+-ATPase activity and H+ pump activity, to clarify the molecular mechanism of Al stress on NO3- uptake of black soybean and its photosynthesis. The main results are as follows:1 Al stress significantly reduced the nitrate uptake of RB and SB. In the absence of Al stress and Al stress on one day, nitrate uptake of the SB is about 4 times of the RB, but with the increasing Al concentration and the extension of stress time, nitrate uptake of the RB in each treatment overtake SB more than two times.Under normal circumstances, the content of H2O2 in RB root is higher than SB, 100?M Al stress makes the contents of H2O2 in SB roots more than 4 times higher than RB, the plasma membrane H+-ATP activity and H+pump activity in RB roots were approximately 7-fold and 10-fold higher than the SB. Respectively. Co-IP analysis confirmed that 100?M Al stress induced the phosphorylation level of RB root plasma membrane H+-ATP and its interaction with 14-3-3 proteins, but inhibited in SB roots. Al stress affect the plasma membrane H+-ATP phosphorylation levels possibly by changing H2O2 content accumulated in the RB and SB, thus changing the interaction of phosphorylated plasma membrane H+-ATP and 14-3-3 proteins, thereby affecting RB and SB root plasma membrane H+-ATPase activity and H+ pump activity, subsequently affect NO3- uptake of RB and SB.2 Al stress significantly reduced soybean photosynthesis. After 4 days of Al stress, the net photosynthetic rate of RB and SB are significantly decreased. However, significant differences between the two treatments are existed. Net photosynthetic rate in non-aluminum stress in RB is two times higher than the SB, RB also significantly higher than the SB under Al stress.The net photosynthetic rate of RB and SB were much lower than CK Under 400?M Al stress, but RB is still significantly higher than SB. Transpiration rate and stomatal conductance of the RB are 40%-50% higher on average than the SB. These parameters in RB are two times higher than SB under high Al concentration stress, and both of them have shown decreased by aluminum stress. But, the higher of the concentration of Al stress, the more apparent advantages of RB compared to SB. However, whether it is the case under the CK or Al stress between, CO2 concentrations between cells in RB and SB were almost unchanged.3 Al stress has a significant impact on the PM-ATPase phosphorylation and its interaction with 14-3-3 protein on soybean nitrate uptake and photosynthetic characteristics. PM-HATPase inhibitor VA completely eliminate the Al stress enhanced the activity of plasma membrane H+-ATP of RB, Mg2+ activator can reverse the Al stress inhibited membrane H+-ATP activity of SB. Al+VA significantly reduced plasma membrane H+ pump activity of RB and Al+Mg2+ enhanced the plasma membrane H+-ATP activity and its interaction with 14-3-3 protein of SB.4 H2O2 involved in the regulation of NO3- uptake and the net photosynthetic rate of RB and SB under Al stress. 100?M Al stressed 4 days significantly increased H2O2 content of SB roots and leaves, but reduced the accumulation of H2O2 in RB roots and leaves. Adding ASA can effectively reduce the H2O2 content of SB under Al stress. In contrast, exogenous H2O2 increased H2O2 accumulation of RB under Al stress. 3mM H2O2+100?M Al can RB decreased PM H+-ATPase phosphorylation and its interaction with 14-3-3 protein of RB.2mM ASA +100 ?MAl SB leaves can increase PM H+-ATP ase phosphorylation and its interaction with 14-3-3 proteinof SB. |
PDF Full Text Request