《植物生理学报》 2018, 54(2): 305-315

不同供氮方式下苹果矮化砧M9T337幼苗生长及内源激素的响应

彭玲, 于波, 陈倩, 葛顺峰^*, 姜远茂^*

作物生物学国家重点实验室, 山东农业大学园艺科学与工程学院, 山东泰安271018

通信作者：葛顺峰；E-mail: geshunfeng210@126.com; ymjiang@sdau.edu.cn

摘　要：

以苹果(Malus domestica)矮化砧M9T337幼苗为试材, 研究了5种不同供氮方式(NO₃^--N浓度由低变高、NO₃^--N浓度由高变低、持续适量供氮、持续低氮及持续高氮, 分别以N1、N2、N3、N4和N5表示)对苹果幼苗生物量、根系形态、内源激素含量及根系硝态氮转运蛋白基因NRT1.1和NRT2.1相对表达量的影响。结果表明, 与N3处理相比, N4处理根冠比增加了11.11%, 而N5处理降低了28.57%。处理第21天, N3处理总根长、总表面积及根长密度最大, 其次为N2处理, 最小的为N5处理, 而叶面积为N3>N5>N2>N1>N4。处理7 d后, N4处理根系吲哚乙酸(IAA)含量显著高于N5处理, 而叶片IAA含量显著低于N5处理。N2处理在NO₃^--N浓度变换11 d内根系IAA含量增加了16.68%, 叶片IAA含量降低了20.90%; N1处理趋势相反。处理21 d内, N5处理根系和叶片玉米素(Z)和玉米素核苷(ZR)含量均显著高于N4处理。各处理根系脱落酸(ABA)含量在处理第21天时无显著差异, 而叶片ABA含量为N4>N2>N1>N5>N3。N4处理根系NRT1.1的相对表达量在处理7 d后显著高于N5处理, 且N4处理1 d后显著诱导了根系NRT2.1的表达。由此推测, 与高氮相比, 低氮下苹果幼苗IAA从地上部向根系极性运输增加, Z和ZR含量降低, 叶片ABA含量积累, 根系NRT1.1和NRT2.1相对表达量提高, 可能是苹果幼苗在不同NO₃^--N浓度下生长差异的重要原因。

关键词：苹果; 根系; 硝态氮; 内源激素; 基因表达

收稿：2017-10-09   修定：2018-01-03

资助：国家重点研发计划项目(2016YFD0201100)、国家自然科学基金项目(31501713)、国家现代农业产业技术体系建设资金项目(CARS-27)、山东省自然科学基金项目(ZR2015PC001)。

Growth response of apple dwarfing rootstock M9T337 seedlings regulated by endogenous hormone under different nitrogen supply

PENG Ling, YU Bo, CHEN Qian, GE Shun-Feng^*, JIANG Yuan-Mao^*

State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, China

Corresponding author: GE Shun-Feng; E-mail: geshunfeng210@126.com; ymjiang@sdau.edu.cn

Abstract:

This experiment was carried out to study the effects of different nitrogen (NO₃^--N) supply on biomass, root morphology, endogenous hormone contents and NRT1.1 and NRT2.1 expression, using apple (Malus domestica) dwarfing rootstock M9T337 seedlings as experiment materials. Five methods for NO₃^--N supply were designed: NO₃^--N concentration varied from deficit to excess (N1), from excess to deficit (N2), keeping appropriate (N3), keeping deficiency (N4) and keeping excess (N5). Results showed that compared with the seedlings under N3 treatment, the ratio of root to shoot was 11.11% higher under N4 treatment and 28.57% lower under N5 treatment. The effect on root length, root surface area and root length density of seedlings was the most significant in N3 treatment, followed by N2 treatment, and least in N5 treatment on the 21th day after treatment, and the leaf area displayed an order of N3>N5>N2>N1>N4. Indole-3-acetic acid (IAA) content was increased significantly in roots but decreased significantly in leaves under N4 treatment after 7 d compared with the seedlings under N5 treatment. Besides, IAA content increased by 16.68% in roots but decreased by 20.90% in leaves under N2 treatment within the 11 d after NO₃^--N concentration variation, while the opposite tendency was showed in N1 treatment. Zeatin (Z) and zeatin riboside (ZR) contents in roots and leaves under N5 treatment were significantly higher than those under N4 treatment within 21 d after treatment. There were no significant differences in abscisic acid (ABA) content in roots across the treatment, while ABA content in leaves displayed an order of N4>N2>N1>N5>N3 on the 21th day after treatment. The relative expression level of NRT1.1 under N4 treatment was significantly higher than that under N5 treatment after 7 d, and the relative expression level of NRT2.1 was increased significantly under N4 treatment on the first day after treatment. It could, therefore, be concluded that compared with high NO₃^--N level, the polar transport of IAA from shoot to root, the decrease in Z+ZR content of roots and leaves, the increase in ABA content of leaves, thus the relative expression of NRT1.1 and NRT2.1 were promoted in the seedlings by nitrogen deficiency. These were important reasons for growth response of apple seedlings to different NO₃^--N levels.

Key words: apple; roots; NO₃^--N; endogenous hormone; gene expression