Effects of Salinity and Abscisic Acid on Lipid Transfer Protein Accumulation, Suberin Deposition and Hydraulic Conductance in Pea Roots.

Guzel R Akhiyarova,Igor I Ivanov,Tatiana V Ovchinnikova,Daria N Melnikova,Ekaterina I Finkina,Tatyana Nuzhnaya,Ruslan S Ivanov,Dmitriy S Veselov,Guzel R Kudoyarova,Ivan V Bogdanov

doi:10.3390/membranes11100762

Guzel R Akhiyarova, Igor I Ivanov + Show 8 more

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https://doi.org/10.3390/membranes11100762

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Journal: Membranes	Publication Date: Oct 1, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: Institute of Bioorganic Chemistry

Abstract

Lipid transfer proteins (LTPs) participate in many important physiological processes in plants, including adaptation to stressors, e.g., salinity. Here we address the mechanism of this protective action of LTPs by studying the interaction between LTPs and abscisic acid (ABA, a “stress” hormone) and their mutual participation in suberin deposition in root endodermis of salt-stressed pea plants. Using immunohistochemistry we show for the first time NaCl induced accumulation of LTPs and ABA in the cell walls of phloem paralleled by suberin deposition in the endoderm region of pea roots. Unlike LTPs which were found localized around phloem cells, ABA was also present within phloem cells. In addition, ABA treatment resulted in both LTP and ABA accumulation in phloem cells and promoted root suberization. These results suggested the importance of NaCl-induced accumulation of ABA in increasing the abundance of LTPs and of suberin. Using molecular modeling and fluorescence spectroscopy we confirmed the ability of different plant LTPs, including pea Ps-LTP1, to bind ABA. We therefore hypothesize an involvement of plant LTPs in ABA transport (unloading from phloem) as part of the salinity adaptation mechanism.

Highlights

Lipid transfer proteins (LTPs) belong to a family of small, ubiquitous proteins that reversibly bind phospholipids and fatty acids within their hydrophobic cavity [1]
Using immunohistochemistry we show for the first time NaCl induced accumulation of LTPs and abscisic acid (ABA) in the cell walls of phloem paralleled by suberin deposition in the endoderm region of pea roots
We reported that salt treatment simultaneously increased both LTPs and ABA abundance accompanied by increased deposition of suberin in roots of pea plants [14]

Summary

Introduction

Lipid transfer proteins (LTPs) belong to a family of small, ubiquitous proteins that reversibly bind phospholipids and fatty acids within their hydrophobic cavity [1]. Preferential LTP localization on the outside of the plasmalemma [4] suggests their involvement in transfer of monomers required for the assembly of water impermeable lipid barriers such as suberin lamellae deposited in the root endodermis. Involvement of LTPs in suberin deposition remains speculative and requires further investigation. Apoplastic barriers such as suberin lamellae protect against uncontrolled flow of water and solutes under abiotic stresses [1]. Responsiveness of LTP genes to drought and salinity stress [5,6] implies an involvement in stress adaptation. In this report deposition of apoplast barriers was not considered as possible mechanism for excluding the sodium

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