Induced Responses Of Root Border Cell Of Pea To Aluminum Toxicity At Different Boron Levels

Root border cells are recently defined alive population sloughed from root tips and loosely adhered in the water soluble mucilage, and the root tip is just the target of Al toxicity, thus it was guessed that border cells might function crucially in the response to Al toxicity. Structure stability of cell wall seems particularly important about keeping cell vigor and function. Boron is regarded as the important component of cell wall, and Al is regarded as having strong cation exchange capacity, the two element are important to cell wall. It has been proved that B could alleviate Al toxicity, but the mechanism is not clear. Aluminum toxicity induced root border cell responses of pea at different B levels was studied toprobe mechanism of B alleviate Al toxicity.Fog culture designed and made by ourself was adopted in the developing of root border cells instead of petri dish to study effect of seed B and solution B on alleviating Al toxicity at different B and Al levels via adding B and Al in the soaking water and fog during the culture process. The results are : B prevents the drop of border cell viability and the cell number caused by Al treatment, decreases the absorb of Al by border cells and prohibits the exchange of cell Ca by Al, thus alleaviates the Al toxicity of border cells. Some other cell wall characteristics are also promising to be important factors in B and Al relationship.1. Fog culture was developed for border cell research. It conspicously increased the feasibility and reliability of the experiment. One national patent (NO. 200420043545.2) on fog culture device was obtained.2.Optimal B level in seed soaking was found (0.1mmol/L) , and it was proved that B could prevent the drop of border cell viability induced by Al. It also found that Al toxicity to border cells is greater than root tip.3. Cell viability reduced by the increase Al concentration from 0 to 100 μ mol/L with time course, the same as the cell number, but the cell viability (250, 500 μ mol/L) is higher than contrast (0μ mol/L) significant. The relative area of mucilage extended by the increase of Al concentration and time course,and it was obviously higher at 500 and 250 μ mol/L,which showed that Al caused cell death at dosage dependent manner at lower Al concentration but not at higher concentration which might relate to the response of border cells to Al toxicity-the thickening of mucilage and the decomposing of border cells.4. External B (seed soaking by 0.1 and 0.5mmol/L B)) and endogenous B (seeds obtained by planting pea in soil with B of 0.25 mg/kg) improved cell viability effectively when exposed to Al toxicity, Which indicated that B could alleviate Al toxicity through promoting cell vibility.5. Cell Ca release from border cells increased with the increase Al concentration from 0 to 500 μ mol/L significant, and cell Ca release was inhibited byboron. Release of Mg,Mn and K) was also decreased by B.Thus indicated that boron can maintain cell stability.