干旱处理下不同烤烟品系的生理差异研究

为培育抗性优良的烤烟品种,探究烤烟的耐旱特性及机理,以烤烟品系LY1306、中烟100和红花大金元为试验材料,研究在聚乙二醇6000(PEG-6000)模拟干旱胁迫和水分控制的干旱处理下,各烤烟品系叶片抗氧化酶类活性,丙二醛(MDA)和脯氨酸含量变化,以及光合生理特性和叶片细胞超微结构的差异。结果表明,25%PEG-6000胁迫下,LY1306能保持较好的生理状态,具有较高的SOD活性和较强的脯氨酸渗透调节能力;中烟100的个别叶片出现萎蔫,SOD活性较LY1306低,较对照组POD和CAT活性显著降低,MDA含量较高;红花大金元叶片出现严重萎蔫,CAT活性降低幅度最大,脯氨酸积累量较高。在反复缺水干旱条件下,LY1306能够维持较高的CAT活性,MDA积累量少,水分利用率较高,蒸腾速率较低,细胞中叶绿体数量和叶绿体形态维持正常。红花大金元的POD活性增长明显,脯氨酸含量显著增长,但MDA积累量较大,叶绿体变形且数量明显减少。中烟100的POD活性较高,脯氨酸积累量较大,叶绿体结构较完整。综上,LY1306在干旱胁迫下具有较强的清除活性氧和脯氨酸渗透调节能力,综合抗旱能力较好。本研究结果为培育抗旱烤烟品种提供了理论依据。

Research on the Differential Physiological Responses in Different Flue-cured Tobacco Lines Under Drought Stress

In order to develop the new elite flue-cured tobacco varieties with strong resistance to drought and to research on its mechanisms, flue-cured tobacco lines LY1306, zhongyan100 and Hongda varieties were used to research the changes of antioxidant enzyme activity, malonaldehyde(MDA) and proline contents in leaves under both 25% PEG-6000 and water shortage stress. Under 25%PEG-6000 treatment,the flue-cured tobacco line LY1306 could keep perfect leaf status, much higher superoxide dismutase (SOD) activity and stronger capability of osmoregulation. Several leaves of zhongyan100 were wilted. The activities of SOD were lower than that in leaf of LY1306. Compared with the contrast treatment, the activities of POD and CAT in the leaf of zhongyan100 were decreased after drought stress while the accumulation of MDA increased. The leaves of Hongda were seriously wilted, the activity of CAT decreased significantly while the accumulation of proline increased. Under the water shortage stress treatment which could induce the repeated drought stress the LY1306 tobacco line could also keep higher catalase (CAT) activity, less accumulation of MDA, higher water use efficiency and lower transpiration rate to finally reduce the water loss through leaf. After repeated drought stress, the LY1306 line could also keep the normal morphology of chloroplasts without obvious decreasing of the number of chloroplasts in the leaf. The activity of POD and content of proline increased significantly in the leaf of Hongda but still accumulated more MDA and the number of chloroplasts decreased as well as the structure was damaged. Zhongyan 100 had higher activities of POD, more proline accumulation and good chloroplast structure. Results showed that the LY1306 line is a very good candidate tobacco variety which has a strong drought resistance and had the good ability to scavenge reactive oxygen species and osmotic adjustment capacity under drought conditions. Researches on the mechanisms of the resistance to drought of LY1306 line will provide clues for the development of drought resistant flue-cured tobacco varieties.