Studies On Waterlogging Tolerance Mechanism And Genetic In Waxy Corn Near-isogenic Lines

In this experiment,a pair of waxy corn resistant and sensitive near-isogenic lines were used as experimental materials.The waterlogging treatment was performed using the nesting method to study the morphological,physiological,photosynthetic and anatomical structures of waxy corn seedlings under stress conditions.The six generations of populations constructed with Zz-R（P₁）×Zz-S（P₂）changes were used as research materials to study the inheritance of major genes plus polygenes in waterlogging stress.The resistance evaluation and breeding of the resistant varieties provide a certain theoretical basis.The main results are as follows:1.Resistant to Zz-R superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）,ascorbate（APX）,glutathione reductase（GR）activity increased compared to the control,and the increase was greater than that of the sensitive Zz-S.With the prolongation of the waterlogging stress,the Zz-R still showed an increasing trend compared with the control,but after 8 days,the Zz-S decreased compared with the control.The MDA contents of Zz-R and Zz-S were higher than those of the control group under waterlogging stress,and the Zz-S increased more than Zz-R.The contents of proline and soluble sugar were also significantly higher than those of the control,and the Zz-R increased higher than Zz-S.Waterlogging stress significantly increased Zz-R pyruvate decarboxylase（PDC）,alcohol dehydrogenase（ADH）and lactate dehydrogenase（LDH）activities,and the activity of each anaerobic respiratory enzyme increased with the prolongation of stress time.The amplitude has decreased,while the activity of PDC,ADH and LDH has decreased significantly in Zz-S,indicating that Zz-R is superior to Zz-S in the adaptability to anoxic environment.2.With the extension of waterlogging stress time,the surface area root of Zz-R,the underground weight,the root length,and the root volume were all higher than the Zz-S increase.The chlorophyll content,P_n,Gs,and Tr of the leaves continued to decline,and the chlorosis content,photosynthetic rate,stomatal conductance,and transpiration rate of the Zz-R leaves decreased more than that of the Zz-S.Both Fv/Fo,Fv/Fm,Φ_PSII and ETR showed a downward trend compared with CK under waterlogging stress,and Zz-R decreased less than Zz-S.3.The garland structure of the leaf was destroyed under the waterlogging stress,and the cell arrangement was disordered and the volume gradually became smaller.The area of the cross section of the large vascular bundle and the area of the xylem were all reduced.The thickness of the upper and lower epidermis of the leaf was gradually thinned,and the length and width of the stomata of the leaf were significantly reduced.Waterlogging stress increased the epidermal cell thickness and the root-porosity rate of waxy corn near-isogenic lines roots.The Zz-S root cortical parenchymatous cells showed different degrees of deformation when the stress was 4 days,and the cell volume gradually decreased and irregular arrangement.Zz-R parenchyma cells are still tightly connected.4.The number of adventitious roots were fitted by two additive-dominanee-epistasis major gene（B-1）.Both additive effect of gene were additive effect,The dominant effect is positive and negative,One pair of major genes showed negative over dominance,and one pair of major genes showed complete dominance.The herit ability of the major gene in B₁ is highest in number of adventitious roots.Under waterlogging stress,antioxidant free radical scavenging system enable waxy corn damage on plant stomatal closure,reduce water loss and through its own osmotic adjustment,maintain a low osmotic potential to increase the resistant.The high level of antioxidant enzyme activity,the development of adventitious roots and the formation of aeration tissue are the important mechanism of waxy corn tolerance to waterlogging stress.