Journal of Agronomy and Field Innovations

Background: The productivity of wheat (Triticum aestivum L.) continues to be in danger because of terminal heat ultimatums that can damage photosynthesis, membrane integrity, and grain growing. Heat shock proteins (HSPs), and especially HSP70 and HSP90 proteins, are highly important in their effect of protein protection and thermotolerance development.
Objectives: In the present study, the expression patterns of HSP70 and HSP90 in wheat under terminal heat stress were compared and their transcriptional responses correlated with physiological determinants of heat tolerance.
Materials and Methods: Two contrasting wheat genotypes were subjected to terminal heat stress (42/28 °C day/night) during anthesis for 6, 24 and 48 hours with unstressed controls kept at 24/18 °C. Transcript abundance of HSP70 and HSP90 was analyzed by qRT-PCR in flag leaf samples. Physiological parameters such as chlorophyll content, membrane stability, relative water content and accumulation of ROS were also analyzed.
Results: HSP70 and HSP90 were significantly induced by heat stress, with HSP70 being induced earlier and stronger than HSP90. At 24 hours of stress, the maximal expression of HSP70 was increased about 9-10-fold and HSP90 was increased about 5-6-fold. Increased membrane damage and ROS accumulation reduced physiological performance under prolonged stress. The heat tolerant genotype showed higher HSP expression and better physiological stability as compare to heat sensitive genotype.
Conclusion: HSP70 and HSP90 play complementary roles in thermotolerance in wheat; HSP70 as an early stress responding protein and HSP90 as a sustained stress regulating protein. Their expression patterns can be used as potential molecular markers for heat-tolerance breeding and development of climate-resilient wheat variety.