摘要：
[目的]氮素营养影响着水稻灌浆过程中核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)和谷氨酰胺合成酶(GS)基因转录表达量,研究其变化动态及其与不同形态氮含量的关系,旨在为阐明氮素营养对光合效率和籽粒蛋白质积累的影响分子调控机理提供理论依据.[方法]选用寒地粳稻穗数型高产品种和穗重型超级稻品种进行盆栽试验.施肥比例为N:P2O5:K2O=1:0.5:1,氮肥50％作为基肥,其余作分蘖肥和穗肥追施,分蘖肥和穗肥比例为10％:40％、20％:30％、30％:20％、40％∶ 10％.分析了水稻灌浆过程中Rubisco和GS基因转录表达量及不同形态氮的积累动态.[结果]增加穗肥氮素施用量可显著提高水稻灌浆过程中叶片和籽粒的全氮、铵态氮、硝态氮含量;增加穗肥比例不同程度的上调了Rubisco大亚基和小亚基基因的mRNA表达量,其中OsRBCSL、OsRBCS2和OsRBCS4表达上调显著,OsRBCS3和OsRBCS5表达上调较小;穗肥比例增加延长了Rubisco各亚基基因高表达持续时间,增加了水稻灌浆中期和后期叶片中OsGS1;1和OsGS2基因的转录表达量以及籽粒OsGS1;1基因的转录表达量和整个灌浆过程中OsGS1;3基因的转录表达量.Rubisco五个亚基基因的转录表达量与叶片NO3--N和全氮含量间以及叶片和籽粒中GS基因的转录表达量与NH4+-N和全氮含量间均呈显著或极显著的正相关.[结论]在灌浆过程中OsRBCL基因和GS基因的转录表达量变化动态不因品种或氮素营养不同而发生质的变化,不同基因对氮素营养的响应程度并不相同,增加叶片NO3--N和全氮含量,可以显著提高Rubisco基因的转录表达量,增加灌浆成熟期叶片和籽粒的NH4+-N和全氮含量,可以显著提高叶片和籽粒的GS基因转录表达量.%[Objectives] Nitrogen nutrition affects the transcription level of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and glutamine synthetase (GS) gene,and studying the relationship between the gene expression and nitrogen supply levels will help understanding mechanism of nitrogen nutrition on rice growth and nitrogen use efficiency at the molecular regulation level.[Methods] In a pot experiment,two rice cultivars of multi-panicle and high yield type and heavy panicle and super japonica cultivar in cold region were used as test materials.The N ∶ P2O5 ∶ K2O input ratio was 1 ∶ 0.5 ∶ 1.HalfofN fertilizer was basal applied,the left was divided into tillering fertilizer and panicle fertilizer,and four ratios of tillering to panicle fertilizers were designed,10％ ∶ 40％,20％ ∶ 30％,30％ ∶ 20％ and 40％ ∶ 10％.The transcription expression of Rubisco and GS gene and the accumulation of different forms of nitrogen in rice leaves at the filling stage were investigated.[Results] The results showed that the contents of total N,NO3-N and NH4+-N of leaves and grains of rice were significantly increased with the increase of the tillering fertilizer rate.Simultaneously,the expression levels of the large and small subunit genes of Rubisco were increased in different extents,among them the expression levels of OsRBCSL,OsRBCS2 and OsRBCS4 were up-regulated significantly,while those of OsRBCS3 and OsRBCS5 were up-regulated to some extent,and the high expression duration of Rubisco subunits gene were extended.The expression level of OsGS1;1 in leaves and grains was enhanced at the middle and late filling stage,while those of OsGS2 gene only showed high expression level in leaves at the middle and late filling stage,and those of OsGS1;3 gene exhibited high expression level during the whole filling stage.The expression levels of five rubisco subunit genes had significant or highly significant positive correlation with the contents of NO3-N and total nitrogen in leaves,and the expression levels of three glutamine synthetase isoenzyme gene had significant or highly significant positive correlation with the contents of NH4+-N and total nitrogen in leaves and grains.[Conclusions] The expression dynamic of OsRBCL and GS genes are not responded to different cultivars or nitrogen supply during the filling stage.High contents of NO3-N and total nitrogen in leaves significantly increased the amount of Rubisco gene transcriptional expression,and high contents of NH4+-N and total nitrogen in leaves and grains significantly increased the amount of GS gene transcriptional expression.
