Cell Biological Mechanisms Of Aluminum Induced On Root Apex Of Different Aluminum-Tolerant Fast-Growing Eucalyptus Clones

Two fast-growing eucalyptus clones E. grandis×E. urophylla GLug9and E. urophylla GLu4were chosen to study the effects of physiological and biochemical differences under aluminum in acidic environment induced for the research of different-resistant mechanism of Al effect on eucalyptus clones, high-quality strain breeding, improving the productivity of eucalyptus plantation in Al-rich red soil region and implementing sustainable management of eucalyptus plantation.Through analyzing root growth, root apex’s Al distribution, morphological structure changes of root apex cells and antioxidant physiology of roots and leaves of the rule of the fast-growing Eucalyptus clones under aluminum-induced, conclusions came to those as following:(1) The root growth and activity of the fast-growing Eucalyptus clones were inhibited or decreased, while the cell membrane permeability of the roots and leaves increased, electrolyte dissolution and lipid membrane per oxidation. But there are differences in performance between clones, growth and activity of root suppressed much small, has limited quantities of electrolyte dissolution and lipid membrane per oxidation due to the less damage of cell membrane in G9as strong aluminum tolerance clone than G4. Damage of leaves was slightly and hysteresis compared to the root under Al in two clones.(2) The Antioxidant enzyme activity was improved in two clones under aluminum-induced. While activity of CAT、APX、GR were heighten more obviously in the roots and leaves of G9than G4. The enhance of GR generated reaction substrate ASA in favor of APX, and played the auxiliary positive role in the antioxidant system which eliminated more effectively H2O2.SOD,PPO activity of G9were low to produce less reactive oxygen species. Effect of Antioxidant system depended mainly on the leaves.(3) The increased amplitude content of Galacturonic Acid of pectin and cellulose in root tips cell walls were greater in G4, which disordered the dysfunctional structure of cell walls. The mass GA content of pectin and hemicelluloses add the sites of adsorbing and cumulation of Al on the cell walls. PME of G4act more significantly than G9, so that mass secretion pectin was hydrolyzed into pectic acid stronger adsorbing more Al, intensifying aluminum toxicity. The proportion of pectin and hemi cellulose I GA and total sugar content and cell walls activity of G4decreased, therefore rigidity of cell walls strengthen and root elongation was limited. The dysfunctional structure of cell walls was less disordered and PME activity changed little in G9.(4) The Al concentration in each fraction decreased in the following pattern: cell wall>cyplasmic supernatant>cell organelle and most of Al in the cell wall fraction was bound to pectin, which was consistent in the two clones. A1 adsorption amount of root apex, cell wall, cell wall pectin and organelles and cytoplasm were less in G9than G4,so as to the damage degree apoptosis of root surface and PCD after microscopy.(5) The results of coefficient variation of the comprehensive evaluation proved G9have stronger Al-resistant mechanism than G4.