新疆野苹果抗寒生理生化机制研究

Study on physiological and biochemical mechanism of cold resistance of Malus sieversii

【目的】确定与新疆野苹果抗寒性紧密相关的生理学指标,为揭示其抗寒性表达的生理机制提供理论依据。【方法】在新疆野苹果中选取抗寒性相对强的种下类型小黄酸野苹果和抗寒性相对弱的种下类型香酸野苹果的1年生枝条为研究材料,分别在其自然越冬时期的休眠前期、休眠期、解除休眠期测定其相对电导率(REC)、可溶性蛋白含量、可溶性糖含量、游离脯氨酸含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性等抗寒生理指标,并通过显著性分析、主成分分析对其各项生理指标进行综合评价。【结果】自然越冬过程中不同时期小黄酸野苹果的电导率始终低于香酸野苹果的,其电导率均在解除休眠期达到最大值,其中小黄酸野苹果电导率最大值为0.37,香酸野苹果的为0.39;小黄酸野苹果电导率的最小值(0.28)出现在休眠期,香酸野苹果电导率的最小值(0.32)出现在休眠前期。可溶性蛋白含量、可溶性糖含量和POD活性总体均呈先升高后降低的变化趋势,且其最大值均出现在休眠期;小黄酸野苹果的可溶性蛋白含量最小值(1.41 mg/g)出现在解除休眠期,显著低于香酸野苹果的最小值(1.69 mg/g);小黄酸野苹果可溶性糖含量在休眠期的最大峰值为5.22%,显著低于香酸野苹果的5.63%;小黄酸野苹果POD活性的最大值为188.23 U/(g·min),远小于香酸野苹果POD活性的最大值295.17 U/(g·min);小黄酸野苹果POD活性在休眠前期出现的最小值为47.53 U/(g·min),显著小于香酸野苹果POD活性的最小值86.27 U/(g·min)。在引种资源圃中,小黄酸野苹果的丙二醛含量最大值出现在休眠前期,为20.36μmol/g,其最小值出现在解除休眠期,为5.36μmol/g;香酸野苹果的丙二醛含量最大值出现在休眠前期,为19.54μmol/g,其最小值出现在休眠期,为4.30μmol/g。游离脯氨酸含量和SOD活性总体均呈先降低后升高的变化趋势,小黄酸野苹果和香酸野苹果均在休眠期达到最小值,均在解除休眠期达到最大值;其中,小黄酸野苹果SOD活性的最小值为47.10 U/(g·h),显著高于香酸野苹果的最小值44.98U/(g·h);小黄酸野苹果游离脯氨酸含量的最小值为55.74μg/g,极显著大于香酸野苹果的最小值33.89μg/g;小黄酸野苹果游离脯氨酸含量的最大值为146.49μg/g,极显著小于香酸野苹果的最大值357.47μg/g。【结论】通过主成分分析可知,超氧化物歧化酶SOD活性、脯氨酸含量、相对电导率均可作为其抗寒性的主要测定指标。由所测数据初步推断出,脯氨酸、POD、可溶性糖在小黄酸野苹果休眠前期,脯氨酸、SOD、POD、丙二醛在其休眠期,脯氨酸、可溶性蛋白、POD、丙二醛在其解除休眠期的抗寒中均发挥着主要作用。

【Objective】To provide theoretical basis for revealing the physiological mechanism of cold resistance expression in Malus sieversii,and to identify physiological indexes closely related to cold resistance.【Method】The 1-year-old branches of M.sieversii f.luteolus with strong cold resistance and M.sieversi f.aromaticus with weak cold resistance were selected as research materials.The relative conductivity(REC),soluble protein content,soluble sugar content,free proline content,malondialdehyde(MDA)content,superoxide dismutase(SOD)activity,peroxidase(POD)activity and other cold-resistant physiological indexes were measured in the early dormancy,dormancy and dormancy stages of the natural overwintering period.Significance analysis and principal component analysis were used to comprehensively evaluate the physiological indexes.【Result】In the course of natural overwintering,the electrical conductivity of the M.sieversii f.luteolus was always lower than that of the M.sieversi f.aromaticus.The maximum value of the electrical conductivity of the M.sieversii f.luteolus was 0.37,the maximum value of the M.sieversi f.aromaticus was 0.39.The minimum value of the electrical conductivity of M.sieversii f.luteolus in the dormancy stage was 0.28,and the minimum value of the electrical conductivity of M.sieversi f.aromaticus in the dormancy stage was 0.32.Soluble protein content,soluble sugar content and POD activity showed a trend of first increasing and then decreasing,and the maximum value appeared in the dormancy stage.The minimum value of soluble protein content in microflavic M.sieversii f.luteolus was 1.41mg/g in the dormancy stage,which was significantly lower than the minimum value of vanic M.sieversi f.aromaticus 1.69 mg/g.The maximum value of soluble sugar content in the M.sieversii f.luteolus was 5.22%,which was significantly lower than that in the M.sieversi f.aromaticus in the dormancy stage(5.63%).The maximum POD activity of pyrrhizic M.sieversii f.luteolus was 188.23 U/(g·min),which was much lower than that of M.sieversi f.aromaticus 295.17 U/(g·min).In the early stage of dormancy,the minimum POD activity of M.sieversii f.luteolus was 47.53 U/(g·min),which was significantly lower than M.sieversii f.luteolus,which was 86.27 U/(g·min).In the introduction resource nursery,the maximum content of malondialdehyde in M.sieversii f.luteolus was 20.36μmol/g in the early dormancy stage,and the minimum value was 5.36μmol/g,when the dormancy stage was about to end;the maximum content of malondialdehyde in pyrrhizic M.sieversi f.aromaticus was 19.54μmol/g in the early dormancy stage,and the minimum value was 4.30μmol/g in the dormancy stage.The content of free proline and the activity of SOD decreased firstly and then increased,and the minimum value of SOD activity of the two kinds of apples was reached in the dormancy stage and the maximum value was reached before the dormancy stage was over.The minimum value of SOD activity of the M.sieversii f.luteolus(47.10 U/(g·h))was significantly higher than that of the M.sieversi f.aromaticus(44.98 U/(g·h)).The minimum content of free proline in M.sieversii f.luteolus was 55.74μg/g,which was significantly higher than 33.89μg/g in M.sieversi f.aromaticus.The maximum content of free proline in M.sieversii f.luteolus was 146.49μg/g,which was significantly lower than that of 357.47μg/g in M.sieversi f.aromaticus.【Conclusion】It can be preliminarily inferred from the data that in terms of cold resistance,the proline,POD and soluble sugar played important roles in early dormancy stage of M.sieversii f.luteolus,while the proline,SOD,POD and malondialdehyde(MDA)played the major roles in its dormancy stage,and the proline,soluble protein,POD and malondialdehyde(MDA)played important roles when lifting the dormancy stage of M.sieversii f.luteolus.