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【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∶P_2O_5∶K_2O=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m RNA表达量,其中Os RBCSL、Os RBCS2和Os RBCS4表达上调显著,Os RBCS3和Os RBCS5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Os GS1;1和Os GS2基因的转录表达量以及籽粒Os GS1;1基因的转录表达量和整个灌浆过程中Os GS1;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Os RBCL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。
【Objective】 The effects of nitrogen nutrition on transcriptional expression of Rubisco and GS in rice during grain filling were studied. The changes of transcriptional levels of Rubisco and glutamine synthetase Its relationship with different forms of nitrogen content aims to provide a theoretical basis for elucidating the molecular regulation mechanism of nitrogen nutrition on photosynthetic efficiency and grain protein accumulation. 【Method】 Potted experiments were conducted on cold-heading panicle type high-yielding varieties and panicle-type super-high-yielding rice varieties. Fertilization ratio of N: P_2O_5: K_2O = 1: 0.5: 1, nitrogen fertilizer 50% as basal fertilizer, and the rest as tillering and panicle top dressing, tillering and panicle fertilizer ratio of 10%: 40%, 20%: 30% 30%: 20%, 40%: 10%. The transcriptional expression of Rubisco and GS genes and accumulation of different forms of nitrogen during rice grain filling were analyzed. 【Result】 Increasing the N application rate in panicle could significantly increase the content of total nitrogen, ammonium nitrogen and nitrate nitrogen in leaves and kernels during rice grain filling. Increasing the panicle proportion increased Rubisco large subunit and small subunit The mRNA expression of m RNA in OsRBCSL, Os RBCS2 and Os RBCS4 was up-regulated significantly, while the expression of Os RBCS3 and Os RBCS5 was little up-regulated. The increase of panicle fertilization prolonged the duration of high expression of Rubisco subunits, The transcriptional expression of Os GS1; 1 and Os GS2 genes and the transcriptional expression of Os GS1; 1 gene and the transcriptional expression of Os GS1; 3 in the middle and late leaves of the grain. The transcript levels of Rubisco five subunit genes were significantly or very significantly positively correlated with NO3 - N and total nitrogen contents and GS gene transcriptional levels in leaf and grain with NH4 + -N and total nitrogen contents . 【Conclusion】 The changes of Os RBCL gene and GS gene transcription during grain filling did not change qualitatively due to different varieties or nitrogen nutrition. The response of different genes to nitrogen nutrition was not the same. Increasing the NO3- N and total nitrogen, could significantly increase the transcript level of Rubisco gene and increase the content of NH4 + -N and total nitrogen in leaves and kernels during grain filling, and significantly increase the transcriptional expression of GS gene in leaves and grains.