不同氮效率油菜NO_3~-长距离运输和短途分配差异及其对氮效率的影响机理

发布时间：2018-03-26 06:04

本文选题：油菜　切入点：氮效率(NUE)　出处：《湖南农业大学》2015年博士论文

【摘要】：油菜是我国重要的油料作物,其生长对氮肥的需求较大,施肥量一般在200kg/hm2以上,但其氮效率(NUE)却较低,氮肥利用率不超过40%。在农业生产上,氮肥的过量施用,不仅造成资源的浪费,而且对环境带来不利影响。因此,提高作物的氮效率对我国农业的可持续发展具有重要意义。本文通过对两个不同氮效率油菜品种(氮高效品种H和氮低效品种L)的转录组研究、探究不同氮效率油菜NO3-长距离运输和短途分配的差异及其对氮效率的影响机理,进一步揭示了油菜NUE基因型差异的本质原因,为提高作物N03-的利用能力和氮素利用效率提供科学理论依据。主要研究结果如下：1、通过对两个不同氮效率油菜品种的转录组研究,共发现1444个差异表达基因,这些差异表达基因显著富集在GO数据库的酶活性调节、授粉、外部刺激反应、逆境反应等节点上。对差异基因的KEGG代谢通路分析表明,两个样本在氨基酸代谢(丙氨酸、谷氨酸等)、其他氨基酸代谢(D-谷氨酰胺、谷胱甘肽等)、次级代谢物的生物合成的代谢通路上,其差异均达到了显著水平。这为我们寻找不同氮效率油菜基因型差异的本质原因提供了重要线索。2、正常供氮水平下,H的NRT1.5的相对表达量显著高于L,NRT1.8的相对表达量显著低于L。且H的蒸腾速率在苗期和盛花期均显著高于L,这导致H有更多NO3-被分配在植物的地上部分。H地下部分的NR、GS活性显著低于L,但地上部分的NR、GS活性显著高于L,且H的叶绿素含量、光合速率均显著高于L。这表明H地下部分的氮同化能力弱于L,但地上部分的氮同化能力强于L。与L相比,H有更多的N03-被运输到植物的地上部分参与同化,这是H的氮效率较高的一个重要原因。但在低氮环境中,H与L的N03长距离运输差异不显著,其氮效率差异也不显著。3、油菜植株的气孔导度、蒸腾速率会随着外界环境中(营养液中)氮水平的降低而增加,一方面可以增强植物对N03-的吸收,提高其氮素吸收效率,另一方面,促使N03-向地上部分的运输分配,且并不会显著降低NR、GS的活性。因此,在低氮环境中,植株通过增加蒸腾速率,促进N03运输到叶中参与同化,这是油菜植株在低氮环境中氮效率升高的重要原因。但在低氮环境中增加的蒸腾速率导致了其水分利用效率的降低。4、由于H的V-ATPase (vha-a2)、V-PPase (avpl)基因的相对表达量均显著低于L,导致H的V-ATPase和V-PPase的活性均显著低于L。这是H液泡的N03-内流速度显著低于L、H+外流速度显著高于L的原因。H有更多的NO3-被分配在细胞质中被还原,这是H的氮效率更高的原因之一。相关性分析表明,N03-含量与V-ATPase活性、V-PPase活性之间均呈显著正相关,且N03-含量与V-ATPase活性之间的相关系数小于N03-含量与V-PPase活性之间的相关系数,这表明V-PPase对N03-从细胞质向液泡内运输的能量贡献大于V-ATPase。
[Abstract]:Rapeseed is an important oil crop in China. The growth of rapeseed has a great demand for nitrogen fertilizer. The amount of fertilizer applied is generally above 200kg/hm2, but its nitrogen efficiency is low, and the nitrogen fertilizer utilization ratio is not more than 400.In agricultural production, the excessive application of nitrogen fertilizer is not more than 40%. Not only the waste of resources, but also the adverse impact on the environment. It is important to improve the nitrogen efficiency of crops for the sustainable development of agriculture in China. In this paper, the transcriptome of two varieties of rapeseed with different nitrogen efficiency (nitrogen efficient variety H and low nitrogen efficiency variety L) was studied. The difference of no _ 3- long distance transportation and short distance distribution and its influence mechanism on nitrogen efficiency in rapeseed with different nitrogen efficiency were explored, and the essential reasons of the difference of NUE genotypes in rape were revealed. In order to improve the utilization ability and nitrogen use efficiency of crop N03-, the main results are as follows: 1: 1, 1444 differentially expressed genes were found by transcriptome study of two varieties of rape with different nitrogen efficiency. These differentially expressed genes were significantly enriched in the nodes of go database such as enzyme activity regulation, pollination, external stimulation response, stress response and so on. The KEGG metabolic pathway analysis of the differentially expressed genes showed that the two samples were metabolized in amino acids (alanine, alanine, alanine). Glutamic acid et al., other amino acid metabolites D- glutamine, glutathione, etc., secondary metabolites in the biosynthesis pathway, The differences reached significant level, which provided us with an important clue to find out the essential reasons of genotypic differences in rape with different nitrogen efficiency. The relative expression of NRT1.5 in H was significantly higher than that in LNRT1.8 at normal nitrogen supply level. The transpiration rate of H was significantly higher than that of Lat seedling and flowering stage, which led to the higher activity of NRGs in H than that of Lin in the aboveground part of the plant and the underground part of H, but the activity of NRN GS in the aboveground part of the plant was significantly higher than that in the subsurface part of the plant. And the chlorophyll content of H, The photosynthetic rate was significantly higher than that of L. this indicated that the nitrogen assimilation capacity of the subsurface part of H was weaker than that of L, but the nitrogen assimilation ability of the aboveground part was stronger than that of L.Compared with that of L, more N03- was transported to the aboveground part of the plant to participate in assimilation. This is an important reason for the high nitrogen efficiency of H, but there is no significant difference in long distance transport between H and L in low nitrogen environment, and there is no significant difference in nitrogen efficiency. 3, stomatal conductance of rapeseed plants. The rate of transpiration increases with the decrease of nitrogen level in the outside environment (nutrient solution). On the one hand, it can enhance the absorption of N03- by plants and improve its efficiency of nitrogen absorption, on the other hand, it can promote the transport and distribution of N03- to the aboveground part. Therefore, in low nitrogen environment, plants promoted the transport of N03 to the leaves to participate in assimilation by increasing transpiration rate. This is an important reason for the increase of nitrogen efficiency in rape plants in low nitrogen environment, but the increase of transpiration rate in low nitrogen environment leads to the decrease of water use efficiency. The activities of both V-ATPase and V-PPase of H were significantly lower than those of L, which was the reason that the velocity of N03- inward flow of H vacuole was significantly lower than that of L0. H was significantly higher than that of L. H had more NO3- to be reduced in cytoplasm. This is one of the reasons for the higher nitrogen efficiency of H. Correlation analysis showed that there was a significant positive correlation between N03- content and V-ATPase activity, and the correlation coefficient between N03- content and V-ATPase activity was lower than that between N03- content and V-PPase activity. This indicated that the energy contribution of V-PPase to the transport of N03- from cytoplasm to vacuole was greater than that of V-AT Pase.
【学位授予单位】：湖南农业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：S565.4

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