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Development of a Cabbage Protoplast System for Studying Hypoxia Tolerance in Brassica
Published on: September 20, 2024
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Brassinolide sustains photosynthesis during high-light stress by modulating mitochondrial electron transport and
Kandarpa Mahati1, Agepati S Raghavendra, Kollipara Padmasree
1Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500 046, India.
Journal of Biosciences
|July 11, 2025
Summary
Brassinolide enhances plant stress tolerance by boosting photosynthesis under high light. It optimizes the mitochondrial electron transport chain (mETC) via the alternative oxidase (AOX) pathway, ensuring plant survival.
Area of Science:
- Plant Physiology
- Molecular Biology
- Biochemistry
Background:
- Plant hormones like abscisic acid and brassinosteroids are known to improve stress tolerance.
- Brassinosteroids, particularly brassinolide, play a crucial role in plant responses to environmental stress.
- High light (HL) stress can impair photosynthetic efficiency in plants.
Purpose of the Study:
- To investigate the role of brassinolide in maintaining photosynthesis under high light (HL) conditions.
- To elucidate the effects of brassinolide on the mitochondrial electron transport chain (mETC) under HL stress.
- To understand how brassinolide influences cellular reactive oxygen species (ROS) levels and their impact on photosynthesis.
Main Methods:
- Treatment of mesophyll protoplasts with brassinolide under high light conditions.
- Analysis of mitochondrial electron transport chain (mETC) activity, including the alternative oxidase (AOX) and cytochrome oxidase (COX) pathways.
- Measurement of gene expression for key mETC components (e.g., AOX1A, COX15).
- Quantification of cellular reactive oxygen species (ROS) levels.
Main Results:
- Brassinolide treatment activated the mETC, particularly the AOX pathway, under HL stress.
- Photosynthesis and PSII activity were sustained under HL with brassinolide addition.
- Brassinolide enhanced AOX pathway capacity while decreasing COX pathway capacity.
- Upregulation of AOX1A transcripts and a marginal increase in cellular ROS were observed.
- Total respiration was enhanced, but with differential modulation of mETC components.
Conclusions:
- Brassinolide enhances plant tolerance to high light stress by optimizing the mETC, specifically through the AOX pathway.
- The modulation of mETC by brassinolide ensures optimal cellular ROS levels, which are crucial for sustaining photosynthesis.
- The study highlights the significant role of mETC in plant stress response and the potential of brassinolide as a tool for improving plant stress tolerance.
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