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为了探索前期不同烟株营养状况协同成熟期氮素调亏对烟叶质体色素代谢影响,筛选出表达水平与氮素水平密切相关的色素转化降解基因。运用盆栽试验,在前期不同氮素营养水平协同后期同量调亏的条件下对烤烟NC297的质体色素含量、成熟期光合速率、叶片超微结构和相关基因表达进行了研究。结果表明:移栽后30～60 d,各时期质体色素含量随着施氮量的增加而增加。随着施氮量的增加,成熟期烟株净光合速率增加;细胞内的嗜锇颗粒、叶绿体和类囊体片层数量增加,衰老特异性半胱氨酸蛋白酶基因CP1的表达逐渐减弱,细胞衰老降解速度减慢。高氮处理N1的脱镁叶绿酸a加氧酶基因PAO在发育后期表达水平高于其他处理;ζ-胡萝卜素脱氢酶基因ZDS、类胡萝卜素裂解双氧合酶基因CCDs和9-顺式环氧类胡萝卜素双加氧酶基因NCED对施氮水平反应敏感,随着施氮量增加其表达高峰向后推移。综上,基因PAO、ZDS、CCDs和NCED表达高峰的出现时间可作为反映后期氮素调亏条件下烟株氮素营养状况是否适宜的有效指标。
In order to explore the effect of nitrogen deficit on the plastid pigment metabolism in tobacco leaves under different nutritional status and synergistic maturity stages, we screened the pigment degradation and degradation genes whose expression level is closely related to the nitrogen level. Pot experiments were carried out to study the plastid pigment content, photosynthetic rate, leaf ultrastructure and related gene expression of flue-cured tobacco NC297 under the condition of the same amount of N uptake and the same amount of regulated loss. The results showed that the contents of plastid pigments increased with the increase of nitrogen application rates at 30-60 days after transplanting. With the increase of nitrogen application rate, net photosynthetic rate of matured tobacco plants increased; the number of intracellular osmiophilic granules, chloroplasts and thylakoids increased, the expression of CP-1, an aging-specific cysteine protease gene, Degradation of aging slowed down. The expression level of pheophorbide a-oxygenase gene PAO in high-nitrogen treatment N1 was higher than that in other treatments at the late developmental stages; Zeta-carotene dehydrogenase gene ZDS, carotenoid cleavage dioxygenase gene CCDs and 9-cis The NCED gene of epicyclic carotenoid dioxygenase was sensitive to nitrogen application and its expression peak shifted backwards with the increase of nitrogen application rate. In summary, the appearance time of peak expression of genes PAO, ZDS, CCDs and NCED could be used as an effective index to reflect the nitrogen nutrition status of tobacco plant under nitrogen-deficient condition.