氮素营养协同成熟期同量调亏对烤烟质体色素和相关基因表达的影响

Effects of Nitrogen Nutrition and Equal Nitrogen Deficiency at Maturing Stage on Plastid Pigment Metabolism and Related Key Genes Expression in Flue-cured Tobacco

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 influence of different nitrogen levels and equal nitrogen deficiency at maturing stage on plastid pigment metabolism in flue-cured tobacco and select the key genes closely related to nitrogen levels of plastid pigment transform and degradation metabolism,pot experiment was conducted.The ultrastructure,net photosynthetic rate and the plastid pigment contents were compared in flue-cured tobacco NC297.The expression levels of several key genes related to plastid pigment metabolism were also analyzed.The results showed that on the 30 d and 60 d after transplanting,the contents of plastid pigment in tobacco leaves increased with the rising of the nitrogen level.The net photosynthetic rates were consistent with the variation of plastid pigment contents.The contents of osmiophilic granule and thylakoid lamella of chloroplast were improved,while the aging and degradation rates delayed with the rising of nitrogen level during the maturity period.The expression of nicotiana tabacum senescence-specific cysteine protease（CP1） was gradually decreased.The expression of pheophorbide a monooxygenase（PAO） in super high nitrogen treatment N1 was siginificantly higher than other treatments at the end of the mature stage.Expression peaks of ζ-carotene desaturase（ZDS）,carotenoid cleavage dioxygenases,CCDs and 9-cis-epoxy carotenoid dioxygenase（NCED） were postponed with the rising of the nitrogen level.In conclusion,the timing of expression peak of gene PAO,ZDS,CCDs and NCED can be used as the index for the evaluation of nitrogen nutrition conditions of the tobacco plants.