Study on Endodermis Development and Apoplast Barrier in Roots of Lycium barbarum L.

doi:10.11924/j.issn.1000-6850.casb2024-0748

Abstract

Abstract:

To investigate the differentiation of the root endodermis and the formation of the apoplast barrier such as Casparian strips and suberin lamella on apoplastic transport pathways in the woody halophyte Lycium barbarum L.(L. barbarum). Using L. barbarum ‘Ningqi No.1’ as experimental material, the development of endodermis and apoplast barrier in the root system of L. barbarum were studied using freehand sectioning combined with fluorescent tracers exploring propidium iodide (PI) and Na⁺ fluorescent probe (CoroNa Green, AM). The results showed that the development of the endodermis structure of L. barbarum can be divided into four developmental phases according to the sequential appearance of Casparian strips and suberin lamella. During the undifferentiated stage, no Casparian strips formation was found in the cell walls, and PI could freely penetrate across both the exodermis and endodermis into the stele. In the first stage, the Casparian strips was observed depositing in endodermal cells and PI could penetrate through exodermis, but was partially blocked its transport at the endodermis, restricting access to the stele. In stage Ⅱ, with well-developed Casparian strips and suberin lamellae, PI penetration to the stele was completely blocked. In stage III, extensive root lignification was observed, accompanied by endodermis degeneration and disappearance of Casparian strips. At the same time, the number of cells associated with the endodermis development showed continuous increasing during root growth, and significant growth was observed from the undifferentiated stage to the appearance of Casparian strips (P<0.05). It indicated that the development of the endodermis in the roots of L. barbarum is divided into four stages. Notably, during the primary growth, the formation of Casparian strips was observed in both endodermis and exodermis of L. barbarum roots, which impeded apoplast flow. However, the exodermis Casparian strips were found lacking apoplastic barrier function.

Key words: Lycium barbarum L., root anatomical structure, endodermis, apoplast barrier, Casparian strips, suberin lamella

MENG Lifang, ZHAO Wangli, JIN Min, MAO Guilian. Study on Endodermis Development and Apoplast Barrier in Roots of Lycium barbarum L.[J]. Chinese Agricultural Science Bulletin, 2025, 41(30): 70-78.

Figures/Tables 10

References 21

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