氮用量对烤烟成熟期叶片碳氮代谢及萜类代谢相关基因表达的影响

Effects of nitrogen on expression of key genes related to carbon/nitrogen metabolism and terpenoid metabolism in matruing flue-cured tobacco leaves

为探索氮用量对烤烟碳氮代谢的影响,在前期不同氮素营养水平上在成熟期统一调亏,分析烤烟叶片糖代谢、氮代谢、淀粉代谢及萜类代谢相关关键基因的表达水平。结果显示:糖代谢中3个关键基因,胞外蔗糖转化酶(Inv)和蔗糖合成酶(SuS)基因随着烟叶的成熟表达量升高,在不同氮水平处理间表达水平差异无统计学意义。蔗糖磷酸合成酶(SPS)基因表达量在烟叶成熟前期随之前施氮量的降低而降低。淀粉代谢中颗粒结合型淀粉合成酶(GBSSI)基因表达量既不受烟叶成熟时期的影响也不受前期供氮水平的影响。氮代谢中硝酸还原酶(NR)基因在不同成熟时期及不同的供氮处理间表达量均无差异。谷氨酰胺合成酶(GS)基因的表达量在烟叶成熟后期呈降低趋势,且受前期供氮水平的影响较大。萜类代谢途径中3-羟-3甲基戊二酰辅酶A还原酶(HMGR)基因表达量随着烟叶的成熟先升高再降低,在成熟后期表达量随前期供氮水平的降低而降低。表明在前期供氮水平不一致的基础上于成熟期统一调亏,对成熟后期烟叶氮素的同化吸收过程和萜类代谢影响较大。烟叶糖代谢和淀粉代谢受烟叶成熟时期的影响最大。

Expression of key genes involved in sugar, nitrogen, starch and terpenoid metabolism pathways were tested by regulated deficit nitrogen nutrition to study effects of different nitrogen applications on carbon and nitrogen metabolism in flue-cured tobacco. Results indicated that in sugar metabolism pathway Inv and SuS genes’ expression increased when tobacco leaf became more mature while not affected by early nitrogen level. Expression of SPS gene decreased with decline of nitrogen supply at early maturing stage. GBSSI gene in starch metabolism pathway was not affected by either maturity or early nitrogen supply. GS gene expressed at lower level in maturing stage and affected by early nitrogen supply while NR gene expression was not affected. HMGR gene expression in terpenoid metabolism pathway decreased when leaf became more mature and decreased with decline of early nitrogen supply. The assimilation of nitrogen and terpenoid metabolism were significantly affected when regulated deficit of nitrogen was applied at early growing stage. Sugar and starch metabolism were affected mostly at leaf maturing stage.