甘蓝型油菜响应低氮胁迫的表达谱分析

Expression profile analysis of low nitrogen stress in Brassica napus

随着人们对作物产量的需求不断提高,氮肥被过量施用,而作物的氮素利用率(NUE)却在不断降低。本研究从低氮胁迫下油菜的生理变化入手,结合高通量的数字基因表达谱测序技术,分析了油菜在低氮0、3、72 h下的转录组差异响应,鉴定了氮的吸收﹑转运﹑分配和转录因子等方面的差异表达基因。结果表明,甘蓝型油菜在低氮处理后,氮优先分配到地上部,硝酸还原酶(NR)活性显著降低,而谷氨酞胺合成酶(GS)活性升高,油菜植株总氮浓度降低,NUE升高。基因基因本位论(GO)功能与京都基因和基因组百科全书(KEGG)代谢通路分析表明,地上部差异表达基因主要是参与代谢过程、蛋白结合、离子结合、阴离子结合等,根中差异表达基因主要是参与分子功能、初级代谢过程、离子结合、阴离子结合等。基因表达谱分析表明,低氮胁迫72 h后,根中BnaGLNs家族基因表达大部分升高;根中BnaWRKY33s和BnaWRKY70s的基因表达量降低;BnaMYB4s、BnaMYB44s和BnaMYB51s亚家族中的大部分基因的表达量降低;BnaNIAs家族中的大部分基因表达上调;在BnaNRT2.1s和BnaNRT3.1s亚家族中,根中BnaA6NRT2.1(BnaA06g04560D)、BnaA6NRT2.1(BnaA06g04570D)、BnaA2NRT3.1(BnaA02g11760D)、BnaC2NRT3.1(BnaC02g16150D)的表达上调。同时,地上部和根发生外显子跳跃(SE),外显子选择性跳跃(MXE)类型的可变剪接积极加强对低氮的适应。总而言之,在低氮处理下,甘蓝型油菜可以通过调控BnaNRTs、BnaGLNs、BnaNIAs家族基因提高NUE,以及调控BnaMYBs、BnaWRKYs家族和可变剪接积极适应低氮胁迫。

The nitrogen fertilizer was overapplied with people’s increased demand for crop yield,but the nitrogen utilization efficiency(NUE)of crops was decreasing.In this study,the differentially expressed genes(DEGs)including the nitrogen absorption,transport,distribution and transcription factors were screened under low nitrogen treatment of 0,3,and 72 h by the physiological changes and RNA-Seq in rapeseed.The results showed that nitrogen were preferentially allocated to the shoots with the increased glutamine synthetase(GS)and NUE activities and the decreased nitrate reductase(NR)activity and the total nitrogen concentration under low nitrogen treatment.The analysis of Gene Ontology(GO)enrichment and the Kyoto encyclopedia of genes and genomes(KEGG)metabolic pathway showed that DEGs of the shoots were mainly involved in metabolic process,protein binding,ion binding,and anion binding,while DEGs of the roots were mainly involved in molecular function,primary metabolic process,ion binding,and anion binding.The gene expression profile analysis indicated that after low nitrogen treatment for 72 h,the expression of most genes in BnaGLNs increased;the expression of BnaWRKY33s and BnaWRKY70s showed significantly decreased in roots;the expression of most genes in BnaMYB4s,BnaMYB44s,and BnaMYB51s decreased in the roots;the expression of most genes in BnaNIAs family was up-regulated in roots;and in the subfamily of BnaNRT2.1s and BnaNRT3.1s,the expression of BnaA6NRT2.1(BnaA06g04560D),BnaA6NRT2.1(BnaA06g04570D),BnaA2NRT3.1(BnaA02g11760D),and BnaC2NRT3.1(BnaC02g16150D)increased significantly in roots.At the same time,skipped exon(SE)and mutually exclusive exons(MXE)type occurred in shoots and roots in order to have a better adaptation under low nitrogen stress.In conclusion,the NUE activity was increased by regulating BnaNRTs,BnaGLNs and BnaNIAs genes,and the BnaMYBs,BnaWRKYs genes and alternative splicing favored Brassica napus to adapt the low nitrogen stress.