Plant Growth Promoting Rhizobacteria Protect Wheat Plants Against Temperature Stress Through Antioxidant Signalling and Reducing Chloroplast and Membrane Injury
In India and other tropics, wheat plants suffer from exposure to high temperature with heat increase above 35 °C causing stress-like conditions. Hence, the present study was aimed to determine a means of suitable eco-friendly temperature stress alleviation for growth of wheat. Seeds of two wheat (Triticum aestivum L.) cultivars were primed with two potential plant growth promoting rhizobacteria (PGPR), Bacillus safensis and Ochrobactrum pseudogrignonense, and 1-month-old young seedlings were subjected to heat treatment for different time periods. PGPR priming improved the heat stress tolerance level of wheat seedlings. Among the two, B. safensis was more effective for improving thermotolerance. High temperature induced the accumulation of ROS and was responsible for membrane injury and chloroplast ultrastructure damage. As a defense reaction, plants in turn activated antioxidant signalling which increased redox enzyme activity and accumulated osmolytes like proline and glycine betaine. However, PGPR priming, especially B. safensis, not only maintained cell viability and restored chloroplast structure thus reducing photosynthetic damage but also improved the antioxidative response significantly which was quite low in uninoculated plants after heat challenge. PGPR-mediated amelioration of heat stress seems to be associated with less ROS production, membrane damage, maintenance of chloroplast structure and enhanced chlorophyll content, increased expression of an array of redox enzymes and accumulation of osmolytes which improved overall thermotolerance. This study revealed a future prospective of eco-friendly and low-cost seed priming technique for amelioration of abiotic stresses.
KeywordsHigh temperature stress Wheat Bacillus safensis Ochrobactrum pseudogrignonense Priming Stress amelioration Thermotolerance
Financial help received from Department of Science and Technology (DST) Govt. of India and assistance from SAIF, AIIMS, New Delhi for transmission electron microscopy are gratefully acknowledged.
Compliance with Ethical Standards
Conflict of interest
The authors declare no conflict of interest.
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