植物根系质外体屏障研究进展

doi:10.11983/CBB21054

摘要/Abstract

摘要： 根是植物吸收水分和矿质营养以维持生命活动的重要器官。根系的构型和超微结构具有物种特异性, 对水分和矿质营养的吸收有不同程度的影响。其中, 内、外皮层的木栓层和凯氏带是2种重要的质外体屏障, 可非定向地阻断水分和离子运输, 在植物生长发育及响应逆境胁迫中发挥重要作用。尽管如此, 植物根系质外体屏障的结构、化学组成、生理功能、生物合成及其调控仅在模式植物拟南芥(Arabidopsis thaliana)中被广泛研究。近年来, 关于作物大麦(Hordeum vulgare)、水稻(Oryza sativa)以及部分牧草的根系质外体屏障研究报道逐渐增多。该文系统比较了拟南芥、大麦、水稻以及部分牧草根系质外体屏障的异同, 提出今后的研究方向, 以期为深入探索禾本科作物和牧草根系质外体屏障在生长发育和逆境适应中的作用奠定理论基础, 并为作物和牧草育种工作提供新思路。

关键词: 质外体屏障, 凯氏带, 根解剖结构, 木栓层

Abstract: Root is the most important organ of plants to absorb water and mineral nutrients for maintaining life activities. The architecture and ultrastructure of roots are species specific with different effects on the water and mineral nutrients absorption. Among them, suberin lamellae and Casparian strip in the endodermis and exodermis are two important apoplast barriers, which block water and ions transport nondirectionally and play important roles in the plant growth and response to stress. However, the structure, chemical composition, physiological functions, biosynthesis and regulation of root apoplast barriers are only studied in Arabidopsis thaliana. In recent years, studies of root apoplast barriers in barley (Hordeum vulgare), rice (Oryza sativa) and some forages have just been reported. In this review, the research progress of root apoplast barriers in A. thaliana, barley, rice and some forages in recent years are compared, and the future research direction is put forward in order to provide a theoretical basis for further exploring the roles of apoplastic barriers of gramineous crops and forages in growth, development and stress adaptation, and provide new ideas for crop and forage breeding.

Key words: apoplast barriers, Casparian strip, root anatomical structure, suberin lamellae

刘鑫, 王沛, 周青平. 植物根系质外体屏障研究进展. 植物学报, 2021, 56(6): 761-773.

Xin Liu, Pei Wang, Qingping Zhou. Research Progress on Apoplast Barriers of Plant Roots. Chinese Bulletin of Botany, 2021, 56(6): 761-773.

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链接本文: https://www.chinbullbotany.com/CN/10.11983/CBB21054

https://www.chinbullbotany.com/CN/Y2021/V56/I6/761

图/表 3

表1 不同植物中木栓质化学组分和含量对比

Table 1 Comparison of chemical constituents and contents of suberin in different plant species

物种	含量单位	脂肪酸	醇	ω-羟基酸	α,ω-二酸	脂肪族	芳香族	总木栓质	参考文献
拟南芥	µg∙cm^-2	0.18	0.14	0.65	0.32	1.30	-	-	Ranathunge and Schreiber, 2011
	µg∙mg^-1DR	2.04	0.81	3.68	1.46	7.99	0.23	8.22	Wang et al., 2020
	µg∙mg^-1DW	2.66	1.86	11.70	5.59	21.81	0.40	22.21	Baxter et al., 2009
大麦	µg∙cm^-2	1.90	0.30	3.20	1.15	6.55	9.55	16.10	Ranathunge et al., 2017
水稻(IR64)	µg∙cm^-2	6.12	1.23	6.69	2.89	17.82	154.29	172.11	Kreszies et al., 2018 Schreiber et al., 2005
水稻(IR64)	µg∙mg^-1DW	3.30	1.25	7.20	1.55	14.19	110.00	124.19	Kreszies et al., 2018 Schreiber et al., 2005
小花碱茅	µg∙mg^-1DR	0.22	0.06	2.14	0.29	2.71	7.47	10.18	杨海莉, 2019

图1 根系质外体屏障的形成及其对根系养分径向运输途径的影响示意图(改自Andersen et al., 2015) 在内皮层未分化阶段, 3种径向运输途径(质外体途径、共质体途径和跨细胞途径)都存在。当发育到阶段I时, 凯氏带形成阻断养分的质外体屏障。当发育到阶段II时, 在次生细胞壁上会沉积木栓质, 凯氏带和木栓层形成阻断养分的质外体屏障和跨细胞屏障。

Figure 1 Schematic view of the formation of root apoplastic barriers and the effects of the radial transport of nutrients in roots (modified from Andersen et al., 2015) In the undifferentiated endodermis, three radial transport pathways (apoplastic, symplastic and coupled trans-cellular) were observed. In stage I, the formation of the Casparian strip blocks the apoplastic pathway of nutrients. In stage II, suberin lamellae was deposited on the secondary cell wall, and the formation of Casparian strip and suberin lamellae blocks the apoplastic pathway and coupled trans-cellular pathway of nutrients.

图2 不同植物根系质外体屏障的超微结构(Ranathunge et al., 2003, 2011a; Lee et al., 2013; Kreszies et al., 2019; Wang et al., 2019; Li et al., 2020; Cohen et al., 2020) (A), (B) 拟南芥初生根的悬置荧光及染色 (A) 拟南芥根凯氏带, 在不同发育阶段, 凯氏带网状结构的自发荧光; 图示从表面到内部纵向的多层共聚焦图像投影, 显示凯氏带的网状结构, 明亮的荧光螺旋结构是木质部导管; (B) 激光共聚焦扫描显微图像, 显示拟南芥根轴上木栓层的积累模式(Z投影), 根细胞壁用碘化丙啶(PI, 红色)突出显示, 而木栓质(黄色)用荧光黄(FY)染色并进行组织化学检测; (C) 大麦根凯氏带, 用小檗碱-苯胺蓝染色, 在阶段II出现完整的绿色荧光, 标志凯氏带完整形成(箭头); (D) FY088染色在阶段II出现完整的黄色环, 表明大麦木栓层完整形成(箭头); (E), (F) 羊草根系凯氏带和木栓层的形成 (E) 用半硫酸小檗碱染色的凯氏带(亮黄蓝色信号, 箭头); (F) FY088染色的木栓层沉积(强烈的黄色信号, 箭头); (G)-(J) 水稻内、外皮层凯氏带及内、外皮层木栓层的形成 (G) 用抗绿色荧光蛋白(GFP)抗体(1:1 000稀释)染色, 绿色荧光显示内皮层凯氏带的形成(箭头); (H) 用小檗碱-苯胺蓝染色, 黄绿色荧光示外皮层凯氏带完整形成(箭头); (I), (J) FY088染色, 黄绿色荧光示木栓层的形成(箭头)。(A), (B) Bars=10 μm; (C)-(F), (H)-(J) Bars=50 μm; (G) Bars=100 μm

Figure 2 Ultrastructure of the root apoplast barriers in different plants (Ranathunge et al., 2003, 2011a; Lee et al., 2013; Kreszies et al., 2019; Wang et al., 2019; Li et al., 2020; Cohen et al., 2020) (A), (B) Suspension fluorescence and staining of primary roots of Arabidopsis thaliana (A) In Arabidopsis thaliana roots, the reticulum of the Casparian strip shows autofluorescence at different developmental stages; the image is a longitudinal, confocal image projection from the surface to the center that visualizes the network structure of the Casparian strip, the bright fluorescent spiral structure of the xylem conduit; (B) Confocal laser scanning micrograph shows the accumulation pattern of suberin lamellae on the root axis of Arabidopsis thaliana (Z projection), the root cell wall is high-lighted with propidium iodide (PI, red), the suberin (yellow) was detected by histochemistry with fluorescence yellow (FY) staining; (C) Barley root Casparian strip, dyeing in berberine-aniline blue at stage II appeared a complete green fluorescent Casparian strip complete form (arrows); (D) FY088 dyeing can appear complete yellow ring in stage II, showed that barley suberin lamellae formed complete (arrows); (E), (F) Formation of Casparian strip and suberin lamellae of Leymus chinensis root system (E) Casparian strip stained with berberine semisulfate (bright yellow blue signal, arrows); (F) Suberin lamellae deposits stained with FY088 (strong yellow signal, arrows); (G)-(J) The formation of the endodermis and exodermis Casparian strip, the endodermis and exodermis suberin lamellae of rice (G) Stained with anti-GFP antibody (1:1 000 dilution), and green fluorescence indicated the formation of the endodermis Casparian strip (arrows); (H) Berberine-aniline blue stain, and the yellow-green fluorescence indicates the complete formation of the exodermis Casparian strip (arrows); (I), (J) Stained with FY088, and the yellow-green fluorescence indicates the formation of the suberin lamellae (arrows). (A), (B) Bars=10 μm; (C)-(F), (H)-(J) Bars=50 μm; (G) Bars=100 μm

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