低氮胁迫对烟草生物学性状、生长素及NtPINs基因家族的影响

为了探究低氮胁迫下烟株体内生长素的分布对烟草根系发育和腺毛发生的影响，以DR5::GUS转基因烟草为材料，通过沙培试验研究低氮胁迫对烟株生物量、全氮含量、叶片及根系发育、生长素浓度、叶片腺毛密度以及生长素极性运输蛋白NtPINs家族基因表达的影响。结果表明:与对照处理（NH₄NO₃:2.5 mmol/L）相比，低氮胁迫下（NH₄NO₃:0.25 mmol/L）烟草上部叶、茎及根部生物量显著下降，地上部全氮含量降低30%，根系全氮含量降低40.2%，上部叶腺毛密度增加13.9%，中部叶和下部叶腺毛密度分别降低40%和31.9%，上部叶生长素含量增加26%，中部叶和根系生长素分别下降7.1%和13.1%；qRT-PCR结果表明，低氮胁迫下烟草根系中NtPIN1、NtPIN4、NtPIN9的基因表达水平分别降低了40%，55%，65%，与对照相比差异均有统计学意义（P < 0.05）。结论:低氮胁迫下烟草叶片腺毛的发生及根系的构型发生改变与体内生长素从地上部（上部叶、中部叶、下部叶）到根系极性运输减少密切相关。 

Effects of nitrogen deficiency stress on tobacco biological characters,auxin and NtPINs gene family

This paper investigated the regulatory effect of auxin on growth of tobacco root and glandular trichome under nitrogen deficiency stress. Sand culture experiment was designed to study effects of nitrogen deficiency stress on tobacco biomass, nitrogen concentration, leaf and root development, auxin concentration, expression of the family gene NtPINs, and efflux protein of auxin. Results showed that, compared with normal nitrogen supply level (NH₄NO₃: 2.5 mmol/L), the biomass of upper leaves, stems and roots decreased significantly under nitrogen deficiency stress (NH₄NO₃: 0.25 mmol/L). Total nitrogen concentration in shoots decreased by about 30%, and that of roots by about 40.2%. The density of trichome of upper leaves increased by 13.9%, and that of middle and lower leaves decreased by 40% and 31.9% respectively. The content of auxin in upper leaves increased by 26%, while that of middle leaves and root system decreased by 7.1% and 13.1% respectively, and that of lower leaves showed no obvious differences. Results of qRT-PCR showed that the expression of NtPIN1, NtPIN3, NtPIN4 and NtPIN9 genes in tobacco roots under nitrogen deficiency stress was significantly lower than that in the control group (P < 0.05). It was concluded that under nitrogen deficiency tress, the growth of auxin in tobacco leaves from upper part of the ground (upper leaves, middle leaves and lower leaves) to the root system is the key factor for the occurrence of glandular trichome and change of root architecture.