Development of Casparian strip in rice cultivars

Abstract

Plant roots are in direct contact with the soil environment and thus particularly affected by unfavorable conditions. To withstand the surrounding environment, roots have developed anatomical and physiological adaptations. The development of Casparian strips (CSs) in the root endo-and exodermis is one such strategy. [1][2][3] In roots of most species, the sequence of development of the endo-and exodermis is roughly the same and involves two consecutive developmental stages: (1) formation of CSs in radial and transverse walls impregnating the primary cell wall pores with lipophilic and aromatic substances and (2) deposition of suberin lamellae to the inner surface of anticlinal and tangential cell walls. [4][5][6] A major function of the CS is to block the non-selective apoplastic bypass flow of water and ions into the stele.3 Therefore, the structure, 7-9 chemical nature, [10][11][12] and physiological function 13,14 of endo-and exdodermal CSs in roots have been the focus of many investigations. Although oxygen loss, drought and salinity can influence the development and chemical nature of CSs in different rice cultivars, [15][16][17][18][19] few investigations have considered the development and formation of endo-and exdodermal CSs in the roots of rice cultivars with different salt tolerance under normal growing conditions.In the present paper, light microscopy and Fourier transform infrared (FTIR) spectroscopy were used to examine the cytochemistry and root anatomy of isolated CSs. The aim was to compare anatomical development and chemical characteristics of the endoand exdodermal CSs of three rice (Oryza sativa L.) cultivars having different salt tolerance in north China: the salt-tolerant Liaohan 109 and two widely grown cultivars, Tianfeng 202 and Nipponbare.The development of casparian strips (cSs) on the endo-and exodermis and their chemical components in roots of three cultivars of rice (Oryza sativa) with different salt tolerance were compared using histochemistry and Fourier transform infrared (FTIr) spectroscopy. The development and deposition of suberin lamellae of cSs on the endo-and exodermis in the salt-tolerant cultivar Liaohan 109 was earlier than in the moderately tolerant cultivar Tianfeng 202 and the sensitive cultivar Nipponbare. The detection of chemical components indicated major contributions to the structure of the outer part from aliphatic suberin, lignin and cell wall proteins and carbohydrates to the rhizodermis, exodermis, sclerenchyma and one layer of cortical cells in series (OPr) and the endodermal casparian strip. Moreover, the amounts of these major chemical components in the outer part of the Liaohan 109 root were higher than in Tianfeng 202 and Nipponbare, but there was no distinct difference in endodermal cSs among the three rice cultivars. The results suggest that the exodermis of the salt-tolerant cultivar Liaohan 109 functions as a barrier for resisting salt stress. Development of Casparian strips and suberin lamellae on the endo-and exodermis. Casparian strips in the end...

Direct fluorescence imaging of lignocellulosic and suberized cell walls in roots and stems

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Genotype Variation in Rice (Oryza sativa L.) Tolerance to Fe Toxicity Might Be Linked to Root Cell Wall Lignification

“…The exodermis and the endodermis are the outer- and innermost cortical layers of a root, and serve as filtration sites for the passive movement of ions between the soil solution and the stele (Ma and Peterson, 2003). These are the root tissue layers where rice deposits Casparian strips, which act as apoplastic diffusional barriers (Cai et al, 2011). Interestingly, work in Arabidopsis showed that Casparian strips are entirely made of a lignin polymer without suberin, contrary to what was previously accepted (Naseer et al, 2012).…”

Fourier transform mid infrared spectroscopy applications for monitoring the structural plasticity of plant cell walls

“…The difference FT-MIR spectra revealed that the content of suberin as well as other cell wall component was higher in the resistant rice cultivar than in the two susceptible cultivars (Cai et al, 2011). …”