The Physiological And Cytological Responses Of Grape Roots And Leaves To Cadmium Chloride Treatment

The experiment was carried out with the cutting seedlings of grape under hydroponics or pot culture. In this experiment, efforts have been made to investigate the following aspects; the compartment of cadmium in root, stem and leaf were studied; the cadmium accumulation coefficient and migration coefficient in twenty varieties of grape were compared; root activity, MDA content, the activity of ATPase in PM of root and leaf, the character of mitochondria and the generation of ROS and NO were detected. Meanwhile, with the analytic system of flow cytometry, detective techonogy of acridine orange fluorescent staining and the activity detection and analysis of caspase3/7. The PCD characters of grape roots were studied. Furthermore, the alleviating effect of exogenous SA and CaCl2 on Ze Xiang grape under cadmium were also discussed.The main results were as follows:1. The compartment and accumulation of cadmium in root, stem and leaf were significantly different. The accumulation rule was: root >leaf > stem. In the twenty varieties of grapes chosen for the experiment, the accumulation coefficient in roots ranged from 39.18% to 135.76% (Zi Zhen-xiang grape being the highest and Victoria the lowest), the accumulation coefficient in stem ranged from 2.55% to 14.32% (Red Globe grape being the highest and Muscat Hamburg grape the lowest), the accumulation coefficient in leaf ranged from 12.06% to 54.61% (Ruby Seedless grape being the highest and Crimson Seedless the lowest) and the migration coefficient of cadmium from root to leaf ranged from 0.16 to 1.12(Zao Yan being the highest and Zi Zhen-xiang the lowest).The total assimilation amount in each of the twenty varieties of grape was in the order as below: Kyoho>Zi Zhen-xiang>Red Globe>Muscat Hamburg>Yatomi Rosa>Ruby Seedless>Ze Xiang>Qtilia Seedless>Manicure Finger>Gui Bao>Crimson Seedless>Zana>Centennial Seedless>Zao Yan>Autumn Royal>Zao He-Bao>Golgen Finger>Tamina>Long Yan>Victoria.2. Within the range of 0～1mmol·L-1, with the increase of CdCl2 concentration, root activity of Ze Xiang, the content of NO in roots and leaves, the activity of NOS and the activity of Ca2+-ATPase rose first and then dropped down; MDA content,O2-·generation rate and H2O2 content had a consistant increase while plasma membrane H+-ATPase had a consistant decrease in roots of Ze Xiang grape. It's worth noticing that the root activity and plasma membrane Ca2+-ATPase activity increased significantly at 0.1 mmol·L-1 CdCl2 in roots of Ze Xiang and plasma membrane ATPase activity, NOS activity, root activity and NO content decreased significantly at 0.5 mmol·L-1 or 1 mmol·L-1 CdCl2 .3. When Zana, Muscat Hambur, Tamina, Gui Bao, Ze Xiang, Red Globe, Kyoho, Qtilia Seedless and Autumn Royal were treated with 0.5 mmol?L-1 CdCl2, the root activity and plasma membrane ATPase activity decreased and the root MDA content,O2-·generation rate and H2O2 content increased. Apart from Otilia Seedless, the content of NO and the activity of NOS in all the rest varieties increased. The root activity of Kyoho was more easily affected by cadmium than the other varieties. The root activity of Qtilia Seedless was the least sensitive and so was least affected by cadmium. The decrease range of root activities for the nine varieties were discribed as below: Kyoho>Autumn Royal>Muscat Hambur>Gui Bao>Red Globe>Zana>Tamina>Ze Xiang>Qtilia Seedless.4. With the increase of CdCl2 concentration within the range of 0～1mmol·L-1, root MPT increased,Δψm decreased, H2O2 content increased, Cyt c content decreased in the root of Ze Xiang grape. The results of flow cytometry indicated that with the increase in treatment concentration, the root cell PCD rate also increased, and the activity of caspase3/7, which is the key enzyme of PCD, too, increased with the increasing of CdCl2 concentration. The result showed that the PCD of grape root cells were induced significantly by CdCl2, which was also reconfirmed by the detection of acridine orange fluorescent staining.5. After treating the roots with 0.5 mmol?L-1 CdCl2, the mitochondrial hydrogen peroxide (H2O2) content increased, mitochondrial permeability transition pores (MPTP) increased, mitochondrial membrane potential (Δψm) decreased, cytochrome c (Cyt c) in roots and root activity decreased and the activity of caspase3/7 increased in the one-year cutting-seedling of 4 grape cultivars (Kyoho, Muscat Hamburg, Long Yan, and Ze Xiang). The order of H2O2 and Cyt c contents was as below: Kyoho>Ze Xiang>Muscat Hamburg>Loing yan the order of root activity, MPTP andΔψm was: Long Yan>Muscat Hamburg>Ze Xiang>Kyoho, and the order of apoptosis rates was: Kyoho>Ze Xiang>Muscat Hamburg>Long Yan. The results indicated that the roots of Kyoho were more easily damaged by CdCl2 than other varieties and thus induced apoptosis.6. Pretreatment of SA at a lower concentration (10μmol·L-1 and 50μmol·L-1) greatly decreased the formation of O2-·, H2O2 and NO, which retarded the declining of root activity and the activity of H+-ATPase and Ca2+-ATPase in PM under 1.0 mmol·L-1 CdCl2 treatment. On the other hand, pretreatment of SA at a higher concentration (100μmol·L-1 and 200μmol·L-1) promoted the formation of free radicals under CdCl2 treatment and further decreased root activity and the activity of H+-ATPase and Ca2+-ATPase in PM. The results indicate that Salicylic acid at a lower concentration can alleviate the damage of CdCl2 to the function of grape roots by inhibiting the formation of free radicals, while at a higher concentration it will aggravate the damage of CdCl2 to grape roots.7. CaCl2 treatment at a lower concentration (1mmol·L-1 and 5mmol·L-1) greatly decreased the formation of O2-·, H2O2 and NO, which retarded the declining of root activity and the activity of H+-ATPase and Ca2+-ATPase in PM under 1.0 mmol·L-1 CdCl2 treatment, alleviated the damage of CdCl2 to the function of grape roots. On the other hand, CaCl2 treatment at a higher concentration (10 mmol·L-1) promoted the formation of free radicals under CdCl2 treatment and further decreased root activity and the activity of H+-ATPase and Ca2+-ATPase in PM, thus aggravated the damage of CdCl2 to grape roots.