过量铜在两个柑橘品种幼苗中的分布特征及根细胞壁响应机制  

The distribution pattern of copper and the responses of root cell wall to excessive copper in seedlings of two citrus species

作　　者：李欣钰 林妹兰 卢飞 胡萍萍 陈立松[1] 黄增荣 LI Xin-yu;LIN Mei-lan;LU Fei;HU Ping-ping;CHEN Li-song;HUANG Zeng-rong(College of Resources and Environment,Fujian Agriculture and Forestry University,Fuzhou,Fujian 350002,China)

机构地区：[1]福建农林大学资源与环境学院,福建福州350002

出　　处：《植物营养与肥料学报》2022年第6期1067-1080,共14页Journal of Plant Nutrition and Fertilizers

基　　金：国家自然科学基金项目(31801950);福建农林大学科技创新项目(CXZX2019079S)。

摘　　要：【目的】探究过量铜在两个柑橘品种幼苗组织水平和亚细胞水平上的分布特征以及根细胞壁对铜毒害的响应机制,以揭示柑橘耐铜毒害机理,为优化不同柑橘品种铜养分管理提供科学依据。【方法】以砂培的雪柑(Citrus sinensis)和沙田柚(Citrus grandis)实生苗为试验材料,进行连续18周不同浓度铜处理,即Cu 0.5μmol/L(对照)和300μmol/L (过量铜)。处理结束后,分析铜在柑橘幼苗不同组织水平(主根、侧根、茎和叶)、侧根亚细胞水平(细胞壁、细胞器和可溶性部分)以及侧根细胞壁多糖组分(果胶、半纤维素Ⅰ、半纤维素Ⅱ和纤维素)上的分布特征;采用透射电镜(TEM)以及傅里叶变换红外光谱(FTIR),分析柑橘侧根细胞壁微结构变化(厚度、化学基团构成等)。【结果】1)组织水平上,不论是对照还是过量铜处理的柑橘苗,侧根是铜分布的主要部位,且过量铜处理的沙田柚侧根铜含量显著高于雪柑。对照组的雪柑和沙田柚侧根铜分布率分别为57.32%和51.31%;过量铜处理后,雪柑和沙田柚侧根铜分布率分别提高到90.87%和91.99%。相反,过量铜处理显著降低了两个柑橘品种幼苗茎和叶的铜分布率。2)在侧根亚细胞水平上,细胞器是铜在对照组柑橘苗的主要分布部位。对照组的雪柑和沙田柚侧根细胞器铜分布率分别为58.61%和39.26%;过量铜处理后,雪柑和沙田柚侧根细胞器的铜分布率分别降低到14.34%和11.49%。与对照相比,过量铜处理显著提高了两个柑橘品种幼苗侧根细胞壁和可溶性部分的铜含量,且过量铜处理的沙田柚侧根细胞壁铜含量显著高于雪柑。3)与对照相比,过量铜处理显著提高了两个柑橘品种幼苗侧根细胞壁各多糖组分的铜含量。其中,对照组的雪柑和沙田柚侧根细胞壁果胶铜分布率分别为44.69%和37.15%;过量铜处理后,雪柑和沙田柚侧根细胞壁果胶铜分布率分别提高到98.45%和98.48%。但过【Objectives】We investigated the distribution pattern of excessive copper(Cu) at the tissue and subcellular levels of two citrus species and the responses of the root cell wall to Cu toxicity with the aims of providing theoretical evidence of citrus Cu-tolerance mechanisms and providing scientific instructions for an optimized Cu nutrient management of citrus species.【Methods】Seedlings of ‘Xuegan’ [Citrus sinensis(L.)Osbeck] and ‘Shatian pummelo’ [Citrus grandis(L.) Osbeck] were sandy cultured in 0.5 μmol/L Cu(control) or300 μmol/L Cu(excessive Cu treatment) nutrient solution for 18 weeks.At the end of treatments,the Cu concentration and the distribution pattern at the tissue level(the primary roots,lateral roots,stems and leaves),subcellular level(the cell wall,organells and soluble fractions) of lateral roots and the cell wall polysaccharides(the pectin,hemicellulose Ⅰ,hemicellulose Ⅱ and cellulose) of lateral roots were analyzed.The alterations of cell wall ultrastructure of lateral roots(the thickness and chemical group constituents) were investigated by transmission electron microscopy(TEM) and Fourier Transform Infrared Spectroscopy(FTIR).【Results】1) At the tissue level,the lateral roots of citrus seedlings were the primary sites of Cu distribution of citrus seedlings under control and excessive Cu treatment.Compared to control,the ratio of Cu distributed in the lateral roots increased from 57.32% to 90.87% and from 51.31% to 91.99%.in C.sinensis and C.grandis,respectively.By contrast,the Cu distribution ratio decreased significantly in the stems and leaves of two citrus species by Cu treatment compared to control.2) At the subcellular level of control seedlings,Cu was mainly distributed in the organells fractions of the lateral roots.However,the excessive Cu treatment decreased the Cu ratio of the control organells fractions from 58.61% to 14.34% and from 39.26% to 11.49% in C.sinensis and C.grandis,respectively.Compared to the control,the excessive Cu treatment increased the Cu co

关 键 词：柑橘 铜分布 细胞壁 透射电镜 傅里叶红外光谱 

分 类 号：S666[农业科学—果树学]