马铃薯品种‘青薯168’和‘陇薯3号’块茎愈伤能力的比较

【目的】研究抗/感干腐病的马铃薯品种‘青薯168’和‘陇薯3号’块茎间愈伤能力的差异,从木质素与软木脂积累以及苯丙烷代谢角度探讨导致差异的原因。【方法】以抗病品种‘青薯168’和感病品种‘陇薯3号’块茎为试材,人工模拟损伤后置于常温下进行愈伤,通过测定损伤块茎愈伤期间失重率的变化和块茎在不同愈伤时期接种硫色镰孢(Fusarium sulphureum)后病情指数的变化评价愈伤效果,利用间苯三酚-HCl和甲苯胺蓝-中性红染色法分别观察块茎损伤部位木质素与软木脂的形成,并量化木质化细胞层厚度和软木脂荧光强度以说明木质素和软木脂的沉积状况,通过测定苯丙烷代谢途径的关键酶和产物即苯丙氨酸解氨酶活性和木质素、总酚与类黄酮含量的变化,比较两个品种块茎愈伤能力的不同。【结果】愈伤期间,‘青薯168’的失重率显著低于‘陇薯3号’。第14天时,‘青薯168’和‘陇薯3号’的失重率分别为0.93%和1.96%,‘青薯168’的失重率比‘陇薯3号’低52.3%。同样,块茎在不同愈伤时期接种硫色镰孢后,‘青薯168’的病情指数也显著低于‘陇薯3号’。愈伤第3天接种,‘青薯168’和‘陇薯3号’的病情指数为20.36和71.59,前者的病情指数比后者低71.5%。愈伤期间,‘青薯168’的木质素与软木脂积累速率显著高于‘陇薯3号’。第14天时,‘青薯168’的木质化细胞层厚度和软木脂荧光总强度分别高出‘陇薯3号’47.4%和60.6%。此外,‘青薯168’愈伤期间表现出较高的苯丙烷代谢活性,其苯丙氨酸解氨酶活性和木质素含量在第14天时分别高出‘陇薯3号’77%和65%。两个品种的总酚含量在愈伤后期也存在差异,第14天时,‘青薯168’的总酚含量高出‘陇薯3号’76%。但两个品种间类黄酮含量在愈伤期间的变化不明显。【结论】抗病品种‘青薯168’的愈伤能力显著高于感病品种‘陇薯3号’,抗病品种所具备的良好愈伤能力与其高活力的苯丙烷代谢密切相关。

Comparison of Healing Ability on Potato Tuber Cultivars ‘Qingshu No. 168’ and ‘Longshu No. 3’

【Objective】The objective of this study is to find out the differences of tuber healing ability of resistant and susceptible potato cultivars against dry rot (‘Qingshu No. 168’ and ‘Longshu No. 3’), and explore the reasons causing differences in the levels of lignin and suberin accumulation and phenylpropanoid metabolism.【Method】The resistant cultivar ‘Qingshu No. 168’ and susceptible cultivar ‘Longshu No. 3’ were used as materials. The damage of tubers was artificially simulated and heal was conducted at ambient temperature. The healing effect was assessed by determining the weight loss and disease index of wounded tubers that were inoculated with Fusarium sulphureum at every healing time point. Phloroglucinol-HCl staining and toluidin blue O-neutral red staining were used to observe lignin and suberin deposition, and the lignified cell layers and suberin fluorescent intensity were quantified. Moreover, the key enzyme and metabolites of phenylpropanoid metabolism pathway such as phenylalanine ammonia lyase activity, and the contents of lignin, total phenol and flavonoid were determined to compare the differences of healing ability between the two cultivars.【Result】The weight loss of ‘Qingshu No. 168’ was significantly lower than that of ‘Longshu No. 3’ during healing. The weight loss of ‘Qingshu No. 168’ and ‘Longshu No. 3’ was 0.93% and 1.96% after 14 days of healing, and the weight loss of ‘Qingshu No. 168’ was 52.3% lower than that of ‘Longshu No. 3’. The disease index of ‘Qingshu No. 168’ was also significantly lower than ‘Longshu No. 3’ after inoculated with F. sulphureum during healing. After 3 days of healing for inoculated tubers, the disease index of ‘Qingshu No. 168’ and ‘Longshu No. 3’ was 20.36 and 71.59, respectively, the former was 71.5% lower than the later. During healing, ‘Qingshu No. 168’ had higher accumulation rate of lignin and suberin than ‘Longshu No. 3’. After healing for 14 days, the thickness of lignified cell layers and total fluorescent intensity of suberin of ‘Qingshu No. 168’ were 47.4% and 60.6% higher than ‘Longshu No. 3’. In addition, ‘Qingshu No. 168’ showed more phenylpropanoid metabolism activity than ‘Longshu No. 3’. The activity of phenylalanine ammonialyase and the lignin content of ‘Qingshu No. 168’ were 77% and 65% higher than ‘Longshu No. 3’after healing for 14 days, respectively. The total phenolics contents of the two cultivars showed a significant difference at late stage of healing, ‘Qingshu No. 168’ was 76% higher than ‘Longshu No. 3’ after healing for 14 days. However, no significant difference was found in the flavonoids content between the two cultivars during healing.【Conclusion】The resistant cultivar ‘Qingshu No. 168’ showed stronger healing ability than susceptible cultivar ‘Longshu No. 3’. A stronger healing ability of resistant cultivar is related with its higher phenylpropanoid metabolism activity.