不同氮效率芝麻品种苗期氮吸收转运与利用差异

Difference in Nitrogen Absorption,Transportation and Utilization of Sesame Varieties with Contrasting Nitrogen Efficiency at Seedling Stage

为探究芝麻苗期氮吸收、转运及利用规律,以2个氮效率差异芝麻品种郑芝HL05(ZZ,氮高效)和缅甸高产者(MD,氮低效)为材料,通过水培试验设置正常(CK,17.86 mmol/L)和低氮(LN,0.2 mmol/L)2个氮浓度处理,比较不同氮效率芝麻在根系形态、氮吸收转运利用、氮代谢指标及相关基因表达等方面的差异。结果表明,不同氮浓度处理下,氮高效品种ZZ的根系形态指标、生物量、氮积累量、氮代谢相关酶活性、根系氮利用效率总体上均高于MD。低氮胁迫显著降低了芝麻的生物量、氮积累量及叶片氮代谢相关酶活性,提高了植株的根系形态指标、根系活力、根冠比、氮生理利用效率、根系干物质利用效率和氮利用效率。其中,氮高效品种ZZ的生物量、氮积累量、转运系数、根系氮生理利用效率和氮利用效率分别是MD的2.48,1.08,1.73,2.36,2.65倍。实时荧光定量PCR结果显示,低氮胁迫下,氮高效品种中,参与NO 3-吸收、转运和再分配的相关基因SiNPF6.3a/b、SiNPF4.6a、SiNRT2.4a/b、SiNRT2.5、SiNPF7.3a/b和SiNPF2.13在叶片中均上调表达,且基因的表达量均高于氮低效品种。综上所述,低氮胁迫下,氮高效芝麻品种苗期具有较为发达的根系和较高的氮素同化、转运及再分配能力,从而获得较高的氮素积累量和氮利用效率。

In order to explore the law of nitrogen absorption,transport and utilization of sesame at seedling stage,two sesame varieties with different nitrogen efficiency,including Zhengzhi HL05(ZZ,high efficiency)and Myanmar high yielder(MD,nitrogen inefficiency)were used as materials.The differences in root morphology,nitrogen absorption,transportation and utilization,nitrogen metabolism indices and related gene expressions involved were compared between the two accessions through hydroponics,under normal nitrogen(CK,17.86 mmol/L)and low nitrogen(LN,0.2 mmol/L)levels respectively.The results showed that under different nitrogen concentrations,the root morphological indexes,biomass,nitrogen accumulation,enzyme activities related to nitrogen metabolism and root nitrogen use efficiency of ZZ variety were higher than those of MD on the whole.Low nitrogen stress significantly decreased the biomass,nitrogen accumulation,and leaf nitrogen metabolism-related enzyme activities,increased root morphological indexes,root activity,root-shoot ratio,nitrogen physiological use efficiency,root dry matter use efficiency and nitrogen use efficiency.Among them,the biomass,nitrogen accumulation,transport coefficient,root nitrogen physiological use efficiency and nitrogen use efficiency of ZZ were 2.48,1.08,1.73,2.36 and 2.65 folds of MD,respectively.qRT-PCR results showed that under low nitrogen stress,SiNPF6.3a/b,SiNPF4.6a,SiNRT2.4a/b,SiNRT2.5,SiNPF7.3a/b and SiNPF2.13 genes involved in NO 3-absorption,transport and redistribution of the nitrogen efficient variety ZZ in leaves were up-regulated,and the gene expression levels were higher than those of the nitrogen inefficient variety MD.In Conclusion,under low nitrogen stress,nitrogen efficient sesame varieties had more developed roots and higher ability of nitrogen assimilation,transport and redistribution at seedling stage,so as to obtain higher nitrogen accumulation and nitrogen use efficiency.