Development, Function, and Environmental Plasticity of the Root Endodermal Diffusion Barrier: from the Casparian Strip to the Suberin Lamellae

doi:10.7525/j.issn.1673-5102.2026.04.003

Abstract

Abstract:

When confronted with complex soil environments such as drought， salinity， and nutrient imbalance， terrestrial plant roots have to achieve a dynamic trade-off between efficient acquisition of water and nutrients， effective blockage of solute leakage， and selective exclusion of harmful ions. The endodermis， a key structural layer in the roots of vascular plants， forms a continuous apoplastic barrier through the Casparian strip and suberin lamellae， thereby maintaining ionic and water homeostasis at the physiological level by regulating radial transport pathways. This review synthesized current knowledge on the biosynthesis， deposition， and structural characteristics of the Casparian strip and suberin lamellae. It further discussed their plasticity under the coordinated regulation of the MYB36 pathway and the Schengen surveillance pathway. Recent advances in understanding the roles of these barrier structures in maintaining mineral nutrient homeostasis， enhancing stress resistance， and mediating rhizosphere interactions were examined. Finally， future research directions were proposed from the perspectives of evolutionary adaptation and crop improvement. This review provided novel insights for a deeper understanding of the adaptive evolution of plant roots and stress-resistant breeding.

Key words: endodermis, Casparian strip, suberin lamellae, diffusion barrier, environmental plasticity

CLC Number:

Hongxia LIN, Jinyuan XIONG, Yuqian ZHANG, Qian NIU, Jiangming WANG, Xi ZHANG, Yuanyuan ZHAO. Development, Function, and Environmental Plasticity of the Root Endodermal Diffusion Barrier: from the Casparian Strip to the Suberin Lamellae[J]. Bulletin of Botanical Research, 2026, 46(4): 599-612.

Figures/Tables 4

Fig.1

Fig.2

Table 1

Summary of factors related to the plasticity of the Casparian strip and suberin lamellae in plant root systems

物种 Species	基因/蛋白名称 Gene/protein name	分子类别/定位 Molecular category/localization	功能注释 Function notes
拟南芥 Arabidopsis thaliana	SHR^［44］	GRAS转录因子/细胞核；可移动信号	促进内皮层分化与径向组织模式建立，为后续屏障结构形成奠定基础；shr突变体内皮层缺失或结构异常
	SCR^［45］	GRAS转录因子/细胞核	调控内皮层与皮层之间的不对称分裂；scr突变体缺失组织、内皮层分化受损
	PER64^［13］	过氧化物酶/细胞壁	催化凯氏带位点木质素聚合，促进凯氏带快速形成与强化；功能缺陷导致木质素聚合不足或形成延迟
	SGN1^［46］	RLCK类激酶/质膜内侧	连接受体与ROS/木质化输出模块，介导Schengen通路信号传递并促进缺口处修复性木质化沉积；sgn1突变体检测信号输出能力减弱
	ABCG2/6/20^［47］	ABCG类半转运体/质膜	介导木栓质前体跨膜输出以构建有效屏障；abcg2/6/20三重突变体木栓质含量降低、屏障通透性升高
	CYP86A1/B1、KCS、GPAT5^［48-49］	脂肪酸合成相关酶/内质网等	决定脂肪族单体的组成谱及供给水平，影响木栓质沉积强度与屏蔽能力；突变改变单体组成并削弱屏障特性
水稻 Oryza sativa	MYB41/53/92/93^［50］	转录因子/细胞核	调控水稻根内皮层木栓质片层形成与非局部木质化；4个基因敲除导致木栓质片层缺失，过表达可诱导提早木栓化并增强盐耐受性
	OsMYB36a/b/c^［51］	转录因子/细胞核	调控根内皮层凯氏带形成，直接激活OsCASP1、OsESB1等凯氏带形成相关基因；3个基因敲除导致突变体内皮层凯氏带缺失并扰乱矿质元素选择性吸收
	OsCASP1^［27］	膜结构域蛋白/凯氏带膜结构域	定位于凯氏带膜域，是水稻根内皮层凯氏带形成所必需的支架蛋白；缺失导致凯氏带发育异常，并影响Ca、Si等矿质元素的选择性吸收
	OsDIR55^［28］	细胞壁相关蛋白/细胞壁	参与根扩散屏障形成与重塑；盐和ABA诱导其表达，过表达可增强根屏障并提高耐盐性
	OsCIF1/2-OsSGN3^［52］	小肽/中柱 LRR受体激酶/内皮层质膜	构成水稻Schengen型小肽-受体激酶监测通路，调控内皮层及非内皮层细胞的凯氏带形成，并协调多种凯氏带形成相关基因表达
	OsGAPLESS1^［23］（GAPLESS家族）	细胞壁定位蛋白（与支架蛋白OsCASP1复合）	介导CSD处膜-壁连接，提高“类紧密连接”密封能力并影响养分稳态；缺失削弱栓系与屏障功能
	ONAC005^［53］	NAC转录因子/根中柱与内皮层	在根中柱和内皮层高表达，直接上调OsTPS8，促进根内皮层木栓质沉积和凯氏带发育；缺失突变体Na⁺积累增加、盐敏感，过表达则增强根疏水屏障形成并提高耐盐性
玉米 Zea mays	ZmSTL1/ZmESBL^［29］	引导蛋白/细胞壁	编码定位于凯氏带域的引导蛋白，调控凯氏带厚度与木质素沉积；突变导致Na⁺经质外体跨内皮层运输增加并降低盐耐性
高粱 Sorghum bicolor	SbCASP-LP1C1^［54］	CASP-like蛋白/根内皮层质膜	于拟南芥异源表达后可降低中柱碘化丙啶染料的渗透、减少根和地上部Na⁺积累，并提高MYB36和ESB1编码基因的表达，提示其参与凯氏带木质素聚合与质外体屏障增强

Table 1

Fig.3

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