不同马铃薯品种苗期叶片对低温胁迫的生理响应

【目的】研究不同马铃薯品种苗期对低温胁迫的生理响应,为探索马铃薯耐寒机制及耐寒品种的早期选育提供理论依据。【方法】以低温敏感型品种费乌瑞它、中薯3号和耐寒品种桂农薯1号、桂农薯4号苗期植株为试验材料,利用人工气候箱进行5℃低温胁迫处理,于处理后0、1、2、3、5和7 d分别取样并测定叶片中过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性及可溶性糖、可溶性蛋白、丙二醛(MDA)和脯氨酸含量。【结果】5℃持续胁迫3 d对叶片造成的伤害在外观形态上开始出现,胁迫5 d后品种间存在明显差异。受低温胁迫后,各品种叶片POD、CAT和SOD活性及可溶性糖、可溶性蛋白和脯氨酸含量整体上均呈升高趋势,峰值出现时间存在差异;随着低温胁迫时间的延长,各生理指标升降变化趋势不同。在低温胁迫5 d时,耐寒品种的酶活性和脯氨酸含量均高于低温敏感型品种,费乌瑞它的可溶性糖和可溶性蛋白含量则显著低于其他品种(P<0.05,下同)。低温胁迫提高了各品种的叶片MDA含量,在低温胁迫第5 d时,低温敏感型品种的MDA含量高于耐寒品种。相关性分析结果表明,SOD活性与可溶性糖含量呈显著正相关,与MDA含量呈显著负相关;POD活性与CAT活性和脯氨酸含量呈显著正相关;CAT活性与脯氨酸含量呈极显著正相关(P<0.01)。【结论】POD、CAT和SOD活性及MDA和脯氨酸含量可作为鉴定马铃薯品种耐寒性强弱的生理指标,低温胁迫第5 d可作为早期筛选耐寒材料的时间节点。4个马铃薯品种苗期耐寒性强弱依次为桂农薯4号>桂农薯1号>中薯3号>费乌瑞它。

Physiological responses of different potato varieties to cold stress at seedling stage

Objective]In order to provide theory basis for understand cold-resistant mechanism and early breeding of cold-tolerant potato varieties, physiological responses of different potato varieties to cold stress was studied at seedling stage. Method]Cold-sensitive varieties viz., Favorita, Zhongshu 3 and cold-tolerant potato varieties viz., Guinongshu 1, Guinongshu 4 were used as tested materials, and treated by cold stress at 5℃in artificial climate box. Activities of perox-idase(POD), catalase(CAT) and superoxide dismutase(SOD) and contents of soluble sugar, soluble protein, malonalde-hyde(MDA) and proline under were determined after 0, 1, 2, 3, 5 and 7 days of cold stress, respectively. Result]Re-sults showed that, leaf damage began to appear on exterior of potato seedling after 3-day prolonged cold stress at 5 ℃, and there was distinctive difference among varieties after 5-day cold stress. In addition, after cold stress, activities of POD, CAT, SOD and contents of soluble sugar, soluble protein and proline in leaves of all varieties increased gradually as a whole, and their peak values for different varieties were different. However, variation trends of all physiological in-dexes in different varieties were different with the increase of cold stress time. After 5-day cold stress, enzyme activities and proline contents of cold-resistant varieties were higher than those of cold-sensitive varieties, contents of soluble sugar and soluble protein in the potato variety Favorato were significantly lower than those in the other varieties(P<0.05, the same below). Furthermore, MDA content in the leaves of all potato varieties increased after cold stress, and MDA content in cold-sensitive varieties was higher than that in cold-resistant varieties after 5-day cold stress. Correlation analysis showed that, SOD activity was significantly positively correlated with soluble sugar content, but significantly negatively correlated to MDA content;POD activity was significantly positively correlated with CAT activity and proline content;CAT activity was extremely significantly positively correlated with proline content (P<0.01). Conclusion]Activities of POD, CAT and SOD, and contents of MDA and proline in potato leaves can be used as physiological indexes to identify cold re-sistance, and the optimal time for early screening cold-resistant materials is at the 5th day after cold stress. Cold resis-tances of four potato varieties at seedling stage are ranked as follows:Guinongshu 4>Guinongshu 1>Zhongshu 3>Favorita.