摘要
【目的】对枳[Poncirus trifoliata(L.)Raf.]与‘资阳香橙’(Citrus junos Sieb.ex Tanaka)在氮胁迫下的无机氮含量、氮同化酶活性与基因表达进行研究,为深入揭示柑橘氮高效利用机制奠定基础。【方法】以采用水培培养的枳与‘资阳香橙’幼苗为试材,进行正常氮水平(10 mmol·L-1,对照)、缺氮(0 mmol·L-1)和高氮(50 mmol·L-1)胁迫处理。【结果】(1)枳与‘资阳香橙’的氮累积量与对照相比,缺氮分别降低了46.6%和51.1%,高氮分别升高了50.4%和81.6%。(2)‘资阳香橙’各处理的硝态氮含量均显著大于枳,枳与‘资阳香橙’叶片中的硝态氮含量以及铵态氮含量各处理均呈高氮>对照>缺氮的趋势。(3)缺氮和高氮处理均显著降低了枳与‘资阳香橙’叶片和根的硝酸还原酶、亚硝酸还原酶、谷氨酰脱氢酶和谷氨酸合成酶活性,而高氮处理时枳叶片中的硝酸还原酶、亚硝酸还原酶、和谷氨酸合成酶的活性与‘资阳香橙’相比被抑制的程度更低。(4)枳和‘资阳香橙’在氮胁迫下叶片中基因NR、NiR、GDH2的相对表达量比对照有明显下降;根系中基因NR、NADH1、NADH3、NADP相对表达量也显著下降。【结论】氮胁迫显著抑制了枳与‘资阳香橙’的氮代谢相关酶活性和氮同化相关酶基因的相对表达量,枳在高氮处理下表现出更高的耐受性‘,资阳香橙’与枳相比有更高的氮吸收能力。
【Objective】’Ziyang Xiangcheng’[Citrus junos Sieb.ex Tanaka]and trifoliate orange[Poncirus trifoliate(L.)Raf.]are widely used as citrus rootstocks in China.There is little information about the physiological and molecular basis of nitrogen utilization in the two citrus rootstocks.In this paper,the content of inorganic nitrogen,and the enzyme activity and gene expression of nitrogen metabolism were studied in the two rootstocks under nitrogen deficiency and excess stresses in order to reveal the mechanism of citrus nitrogen efficient utilization and lay a foundation for further study on the nitrogen transport function of citrus rootstocks.【Methods】The experiment was conducted in the Citrus Research Institute of the Chinese Academy of Agricultural Sciences,Beibei,Chongqing.The seed coats of’Ziyang Xiangcheng’and trifoliate orange were removed,and then seeds germinated in relative humidity of 70%at 27℃under darkness for 7 d.Subsequently,the germinated seedlings were transferred to a modified Hoagland solution(pH 6.0±0.5)at 25℃under a 16 h photoperiod(50μmol·m-2·s-1)for 30 d.The nutrient solution was replaced every 5 d.Three nitrogen(N)levels including normal nitrogen level(10 mmol·L-1,control),N deficiency stress(0 mmol?L-1)and N excess stress(50 mmol?L-1)were used in this experiment.The pots were distributed among a randomized complete block design with nine replicates.After 20 d of nitrogen stress treatments,the roots and leaves were collected and immediately frozen in liquid nitrogen,then stored at-80℃for analyzing the Physiological and biochemical parameters related to nitrogen metabolism.The harvested roots and leaves were rinsed with deionized water 3 times,the water was absorbed with quantitative filter paper,then the samples were dried in a forced draft oven at 80℃for 72 h to a constant weight.The dry weight was measured.Then they were stored in a desiccator for analyzing N content.The activities of NR,NiR,NADH-GDH,and GOGAT were determined according to the method of Experimental guide of modern plant physiology,and the expressison level of nitrogen metabolism relevant genes were analyzed by qRT-PCR.【Results】Compared with the control,nitrogen deficiency significantly reduced the nitrogen accumulation in’Ziyang Xiangcheng’and excess nitrogen significantly increased the nitrogen accumulation in the two citrus rootstocks.The total nitrogen accumulation of’Ziyang Xiangcheng’was significantly higher than that of trifoliate orange.This result might be caused by the higher biomass and root hair density of’Ziyang Xiangcheng’.In the roots and the leaves,the nitrate content of’Ziyang Xingcheng’was significantly higher than that of trifoliate orange.The highest nitrate content in the leaves of trifoliate orange and’Ziyang Xiangcheng’,was found when they were treated with high nitrogen,followed by the control and low nitrogen treatment.Similar results were obtained for the ammonium content.We further measured the expression of nitrogen metabolism-related genes.The relative expression levels of genes such as FdGOGAT,NR,NiR and GDH2 in the leaves of trifoliate orange under N deficiency condition were significantly lower than those of the control,and nitrogen stresses significantly increased the relative expression of genes such as NADH-GOGAT1,NADH-GOGAT2 and NADH-GOGAT3.Meanwhile,the relative expression levels of genes such as NR,NiR,GDH1,GS and GDH2 in’Ziyang Xiangcheng’leaves under nitrogen stresses were significantly lower than those of the control.the relative expression levels of NR,NADH-GOGAT1,NADH-GOGAT3 and NADP-GDH genes were significantly lower than those of the control,while there was almost no change in expression levels of genes such as Fd-GOGAT and GDH1.Similarly,the relative expression level of the genes Fd-GOGAT,NR,NiR,NADH-GOGAT1,NADH-GOGAT2,NADH-GOGAT3 and NADP-GDH in the roots of’Ziyang Xiangcheng’under nitrogen stresses were significantly lower than those of the control.The relative expression of the gene GDH2 was not significantly different from that of the control.We also found that the nitrogen deficiency and high nitrogen treatment significantly reduced nitrate reductase,nitrite reductase,glutamyl dehydrogenase and glutamate synthase in the leaves and the roots of’Ziyang Xiangcheng’and trifoliate orange.The trends in the activities of NR,NiR,NADH-GDH,and GOGAT were consistent with those of NR,NiR,NADH-GDH and GOGAT transcription,respectively.All above results showed that nitrogen stresses significantly reduced the activities of nitrogen-related enzymes in trifoliate orange and’Ziyang Xiangcheng’,resulting in the reduction of nitrate absorption and ammonium production.【Conclusion】Nitrogen deficiency significantly reduced the nitrogen content and the activity of nitrogen-related enzymes and the expression of nitrogen-related genes in the roots and the leaves of trifoliate orange and’Ziyang Xiangcheng’.Trifoliate oranget showed higher tolerance under high nitrogen treatment compared with’Ziyang Xiangcheng’,and’Ziyang Xiangcheng’had higher nitrogen absorption capacity compared with trifoliate orange.
作者
朱礼乾
沈鑫健
周上铃
曾瑶
彭良志
付行政
凌丽俐
淳长品
ZHU Liqiana;SHEN Xinjiana;ZHOU Shangling;ZENG Yao;PENG Liangzhi;FU Xingzheng;LING Lili;CHUN Changpin(Citrus Research Institute of Southwest University/Citrus Research Institute of Chinese Academy of Agricultural Sciences,Chongqing 400712,China;College of Horticulture and Landscape Architectrue,Southwest University,Chongqing 400712,China)
出处
《果树学报》
CAS
CSCD
北大核心
2020年第4期449-458,共10页
Journal of Fruit Science
基金
国家重点研发计划课题(2018YFD0201507,2017YFD0202006)
重庆市社会民生科技创新专项(cstc2017shms-xdny80028)。
关键词
枳
'资阳香橙’
砧木
氮代谢
氮胁迫
相关基因表达
Trifoliate orange
’Ziyang Xiangcheng’
Rootstock
Nitrogen metabolism
Nitrogen stress
Expression of related genes
作者简介
共同第一作者:朱礼乾,男,在读硕士研究生,主要从事果树栽培与生理研究。Tel:15520087835,E-mail:1172023107@qq.com;共同第一作者:沈鑫健,男,在读硕士研究生,主要从事果树栽培与生理研究。Tel:13047310296,E-mail:1129971502@qq.com;通信作者:淳长品,Tel:13883396612,E-mail:chuncp@cric.cn。
