Abstract:

Brassinolide (BL) mediates various physiological processes and improves plant tolerance to abiotic stresses. However, the effects and mechanism of exogenous BL on the salt tolerance of apple seedlings remain unclear. Herein, we investigated the role of BL in the salt stress response of Malus hupehensis Rehd., a widely grown apple rootstock. Salt-stressed apple seedlings showed significant decline in chlorophyll content and photosynthetic rate, and the application of 0.2 mg/L exogenous BL alleviated salt stress and maintained photosynthetic capacity. Exogenous BL application can strengthen the activities of superoxide dismutase and catalase and thereby eliminates reactive oxygen species (ROS) production induced by salt stress and promote the accumulation of proline and soluble sugar, thus maintaining osmotic balance. Furthermore, exogenous BL application decreased Na⁺ accumulation and increased K⁺ content in shoots and roots under salt stress by regulating the expression levels of Na⁺(K⁺)/H + antiporter genes (MhNHXs). MhBZR1 and MhBZR2, which are the key transcription factors in the BR signal transduction pathway, can directly bind to the promoter of MhSOS1 and MhNHX4-1, respectively, and inhibit their expression. Our findings would provide a theoretical basis for analyzing the mechanism of exogenous BL application on the salt tolerance of apples.

Open in

PUBMED | DOI | PMC | Google Scholar | Wikipedia

Relations:

Content

Citations

(5)

Drugs

(2)

Chemicals

(10)

Organisms

(1)

Processes

(6)

Anatomy

(1)

Exogenous Brassinolide Alleviates Salt Stress in Malus hupehensis Rehd. by Regulating the Transcription of NHX-Type Na+(K+)/H+ Antiporters

Click here for additional data file.^{(450K, pdf)}

^{College of Horticulture, Qingdao Agricultural University, Qingdao, China}

^{Qingdao Key Laboratory of Genetic Improvement and Breeding in Horticulture Plants, Qingdao Agricultural University, Qingdao, China}

Edited by: Jayakumar Bose, University of Adelaide, Australia

Reviewed by: Kamrun Nahar, Sher-e-Bangla Agricultural University, Bangladesh; Changhai Liu, Northwest A&F University, China

*Correspondence: Caihong Wang, moc.621@8606whc

This article was submitted to Plant Abiotic Stress, a section of the journal Frontiers in Plant Science

†These authors have contributed equally to this work

Edited by: Jayakumar Bose, University of Adelaide, Australia

Reviewed by: Kamrun Nahar, Sher-e-Bangla Agricultural University, Bangladesh; Changhai Liu, Northwest A&F University, China

Received 2019 Jun 19; Accepted 2020 Jan 13.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Abstract

Brassinolide (BL) mediates various physiological processes and improves plant tolerance to abiotic stresses. However, the effects and mechanism of exogenous BL on the salt tolerance of apple seedlings remain unclear. Herein, we investigated the role of BL in the salt stress response of Malus hupehensis Rehd., a widely grown apple rootstock. Salt-stressed apple seedlings showed significant decline in chlorophyll content and photosynthetic rate, and the application of 0.2 mg/L exogenous BL alleviated salt stress and maintained photosynthetic capacity. Exogenous BL application can strengthen the activities of superoxide dismutase and catalase and thereby eliminates reactive oxygen species (ROS) production induced by salt stress and promote the accumulation of proline and soluble sugar, thus maintaining osmotic balance. Furthermore, exogenous BL application decreased Na^{accumulation and increased K}^{content in shoots and roots under salt stress by regulating the expression levels of Na}^(K^)/H⁺ antiporter genes (MhNHXs). MhBZR1 and MhBZR2, which are the key transcription factors in the BR signal transduction pathway, can directly bind to the promoter of MhSOS1 and MhNHX4-1, respectively, and inhibit their expression. Our findings would provide a theoretical basis for analyzing the mechanism of exogenous BL application on the salt tolerance of apples.

Keywords: brassinolide, oxidative stress, plant hormone, ion homeostasis, MhNHXs

Abstract

Click here for additional data file.^{(450K, pdf)}

Collaboration tool especially designed for Life Science professionals.Drag-and-drop any entity to your messages.

Learn More

Exogenous Brassinolide Alleviates Salt Stress in <em>Malus hupehensis</em> Rehd. by Regulating the Transcription of NHX-Type Na<sup>+</sup>(K<sup>+</sup>)/H<sup>+</sup> Antiporters

Abstract