Preprint Article Version 1 This version is not peer-reviewed

Populus trichocarpa EXPA6 Increases Salt Sensitivity by Facilitating Radial and Longitudinal Transport of Sodium Ions in Poplars

Zhe Liu
,
Kexin Yin
,
Ying Zhang
,
Caixia Yan
,
Ziyan Zhao
,
Jing Li
,
Yi Liu
,
Bing Feng
,
Rui Zhao
,
Jian Liu
,
Kaiyue Dong
,
Jun Yao
,
Nan Zhao
,
Xiaoyang Zhou
,
Shaoliang Chen
*
Version 1 : Received: 10 August 2024 / Approved: 12 August 2024 / Online: 12 August 2024 (14:52:09 CEST)

How to cite: Liu, Z.; Yin, K.; Zhang, Y.; Yan, C.; Zhao, Z.; Li, J.; Liu, Y.; Feng, B.; Zhao, R.; Liu, J.; Dong, K.; Yao, J.; Zhao, N.; Zhou, X.; Chen, S. Populus trichocarpa EXPA6 Increases Salt Sensitivity by Facilitating Radial and Longitudinal Transport of Sodium Ions in Poplars. Preprints 2024, 2024080833. https://doi.org/10.20944/preprints202408.0833.v1 Liu, Z.; Yin, K.; Zhang, Y.; Yan, C.; Zhao, Z.; Li, J.; Liu, Y.; Feng, B.; Zhao, R.; Liu, J.; Dong, K.; Yao, J.; Zhao, N.; Zhou, X.; Chen, S. Populus trichocarpa EXPA6 Increases Salt Sensitivity by Facilitating Radial and Longitudinal Transport of Sodium Ions in Poplars. Preprints 2024, 2024080833. https://doi.org/10.20944/preprints202408.0833.v1

Abstract

Expansins are cell wall (CW) proteins that mediate the CW loosening and regulate salt tolerance in a positive or negative way. The transcription of Populus trichocarpa expansin A6 (PtEXPA6) was downregulated upon prolonged duration of salt stress (48 h) after a transient increase induced by NaCl (100 mM). The role of PtEXPA6 in salt tolerance was determined by transferring the PtEXPA6 gene into the hybrid species Populus alba × P. tremula var. glandulosa clone 84K (84K) and Populus tremula × P. alba INRA '717-1B4' (717-1B4). The PtEXPA6-transgenic poplars of 84K and 717-1B4 showed a greater reduction in photosynthesis, stem height and diameter growth under salt stress and a reduced capacity for ROS scavenging by antioxidant enzymes, which is associated with excessive Na+ accumulation in roots and shoots. NMT flux recordings showed that the radial translocation of Na+ salt into the root xylem and real-time Na+ translocation from roots to leaves were greater in PtEXPA6-transgenic poplars than in wild-type poplars. Analysis of comparative contractility and comparative extensibility of intact root tips indicated that PtEXPA6 increased the CW loosening in the transgenic poplars of 84K and 717-1B4. Noteworthy, the PtEXPA6-promoted CW loosening was shown to facilitate radial and longitudinal transport of Na+ in transgenic poplars. We conclude that overexpression of PtEXPA6 leads to CW loosening that facilitates radial translocation of Na+ into the root xylem and subsequent Na+ translocation from roots to leaves, resulting in excessive Na+ accumulation and consequently reduced salt tolerance in transgenic poplars.

Keywords

Populus; expansin; cell wall loosening; comparative contractility, comparative extensibility, Na+ fluxes; photosynthesis; SOD; POD; CAT

Subject

Biology and Life Sciences, Plant Sciences

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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