中国农业科学 ›› 2017, Vol. 50 ›› Issue (9): 1684-1693.doi: 10.3864/j.issn.0578-1752.2017.09.014

• 园艺 • 上一篇    下一篇

硝态氮影响菊花根系形态结构变化的分子基础

郭芸珲,于媛媛,温立柱,孙翠慧,孙宪芝,王文莉,孙霞,郑成淑   

  1. 山东农业大学园艺科学与工程学院/山东省中日韩菊花国际合作研究中心,山东泰安 271018
  • 收稿日期:2016-10-27 出版日期:2017-05-01 发布日期:2017-05-01
  • 通讯作者: 郑成淑,Tel:0538-8246139;E-mail:zcs@sdau.edu.cn
  • 作者简介:郭芸珲,E-mail:2550031106@qq.com
  • 基金资助:
    国家科技支撑计划(2011BAD10B07)

Molecular Basis of the Effects of Nitrate Signal on Root Morphological Structure Changes of Chrysanthemum

GUO YunHui, YU YuanYuan, WEN LiZhu, SUN CuiHui, SUN XianZhi, WANG WenLi, SUN Xia, ZHENG ChengShu   

  1. College of Horticulture Science and Engineering, Shandong Agricultural University/Chrysanthemum Research Center of China, Japan and Korea in Shandong Province, Tai’an 271018, Shandong
  • Received:2016-10-27 Online:2017-05-01 Published:2017-05-01

摘要: 【目的】通过观察硝态氮处理下菊花根系外观形态和解剖结构、根系和叶片中硝态氮含量、内源激素水平以及根系硝态氮转运蛋白基因和侧根发育特异基因表达量的变化,揭示硝态氮对菊花根系发育的影响及其分子基础,为氮素高效利用的菊花分子育种提供依据。【方法】利用菊花扦插生根苗的水培试验,用10 mmol·L-1 KNO3处理(对照为不含N元素的Hogland营养液)后,分别在第0、1、3、7、14、21和28天观察菊花根系外观形态和解剖结构,测定根系和叶片硝态氮(NO3-)、吲哚-3-乙酸(IAA)和细胞分裂素(CTK)含量,克隆菊花根系硝态氮转运蛋白基因CmNRT1.1、CmNRT2.1、CmNAR2.1和侧根发育特异转录因子基因CmANR1的cDNA保守序列片段,并用实时荧光定量PCR技术检测它们在根系中的相对表达量。【结果】与对照相比,处理的根系总根长、平均直径、总表面积、总体积和根尖数至处理第3天均没有显著差异,但第7天时均显著增加,且随着处理时间的延长,增加的幅度增大。显微观察第28天时的根横切面表明,与对照相比,1级根、2级根和3级根的维管束直径和维管束占根横切面的比值均出现了不同程度的增加。处理的根系和叶片的NO3-含量分别在处理第7天和第14天时达到高峰(峰值分别为0.45和0.35 mg·g-1 FW),之后虽有所回落,但与对照相比始终处于较高水平(对照的根系和叶片硝态氮含量分别保持在0.17—0.27 mg·g-1 FW和0.16—0.22 mg·g-1 FW)。处理的根系、叶片的IAA和CTK含量与对照相比均显著增加,根系IAA和CTK含量高峰在第7天出现,叶片的在第14天出现,而对照的IAA和CTK含量无明显变化。处理的根系硝态氮信号感应和低亲和型转运蛋白基因CmNRT1.1的相对表达量高峰出现在第1天(对照也为第1天);高亲和型硝态氮转运蛋白基因CmNRT2.1和二者的互作蛋白基因CmNAR2.1的相对表达量高峰均出现在第3天(对照在第3天稍微增加后保持相对稳定);菊花侧根发育基因CmANR1的相对表达量在第7天达到高峰(对照为第14天)。硝态氮处理后这4个基因的相对表达量与对照相比始终处于较高水平,表达趋势也相似,都是先升高后降低再保持相对稳定,表明它们均受硝态氮信号诱导。【结论】菊花根系能通过硝态氮转运蛋白基因和侧根发育基因的表达来响应生长介质中的硝态氮信号,进而调控根系构型的改变,来提高菊花根系对硝态氮的吸收和利用。

关键词: 菊花, 根系, 硝态氮, 内源激素, 基因表达

Abstract: 【Objective】 In order to reveal the root morphology and molecular basis of the response of nitrate nitrogen to root development of chrysanthemum, and provide a basis for chrysanthemum breeding to improve the efficiency of nitrogen, this study was carried to investigate the changes of root morphology and structure, the contents of nitrate nitrogen and endogenous hormones, the nitrate nitrogen transport genes and root formation gene of chrysanthemum. 【Method】 The rooted cuttings of chrysanthemum were used in water-culture system in this experiment, then treated by 10 mmol·L-1 KNO3 while control was treated with Hogland nutrient solution without nitrogen. On the day 0, 1, 3, 7, 14, 21 and 28 after treatment, anatomical structures were observed, the contents of NO3-, IAA and CTK in the roots and leaves were measured, the cDNA conserved sequence fragments of CmNRT1.1, CmNRT2.1, CmNAR2.1 which were identified as the NO3- transport protein genes and CmANR1 which were identified as the lateral root differentiation gene of the roots were cloned, and the relative expression levels of them were observed using quantitative real-time PCR. 【Result】The results showed that: There were no significant differences were observed in the overall length, average diameter, total surface area and total volume of roots between NO3- treatment and control within the first 3 days, they were increased significantly after 7 days compared with those of control. The cross sections of roots were also observed on the day 28 after treatments. The vascular bundle diameter of the 1st root, 2nd root and 3rd root after NO3- treatments were increased significantly compared with those of control. The ratios of vascular bundle to root diameter of the 1st root, 2nd root and 3rd root were significantly increased compared with those of controls. The NO3- contents of chrysanthemum reached the peak on the day 7 (0.45 mg·g-1 FW) in the roots and on the day 14 (0.35 mg·g-1 FW) in the leaves, respectively, then both of them decreased slightly, but they were maintained higher level compared with those of control on all days. Compared with those of control, the contents of IAA and CTK in roots and leaves in the NO3- treatments were significantly increased. The peaks of the contents of IAA and CTK in the roots appeared on the day 7 and those of in the leaves appeared on the 14 day after treatments, while the IAA and CTK contents of controls showed no significant change. The relative expression levels of CmNRT1.1 gene’s peak were appeared on the 1 day after treatment (the control also on the day 1). The relative expression levels of CmNRT2.1 and CmNAR2.1’s peaks were appeared on the day 3 after treatment (the control slightly increased on the day 3 and remained relatively stable). While the relative expression levels of CmANR1 reached the peak on the day 7 after treatment (the control on the day 14), and the relative expression levels of the 4 genes maintained higher levels than those of control throughout the experiment. The results showed that the 4 genes were induced by nitrate, and their expression trends were similar, which were increased at first, decreased later and then remained relatively stable. 【Conclusion】 The roots of chrysanthemum could respond to nitrate signal in the growth medium. The response is realized through the expression of nitrate transporter genes and lateral root development gene, and then adjust the configuration of the roots to improve the absorption and utilization of nitrate in chrysanthemum roots.

Key words: Chrysanthemum morifolium, root, NO3-, endogenous hormones, gene expression