Evaluation of antioxidant defense in response to heat in rice cultivars contrasting for thermotolerance.

• Grant number: 24/03165-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2024
• End date: January 31, 2025
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal Investigator: Victória de Carvalho
• Grantee: Luana Ramos dos Santos
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/13158-8 - Transcriptome-wide analysis of rice temperature memory and heat responses, AP.JP

Abstract

The vulnerability of rice (Oryza sativa) to increasing global temperatures induced by climate change is a threat to food security, as it is the main food in the diet of half of the world's population. Basal thermotolerance (BTt) and acquired thermotolerance (ATt) are important defense strategies against heat stress in plants. ATt allows plants to develop tolerance to severe heat when previously exposed to non-lethal heat stress, a process known as priming. The type of thermotolerance varies among different species and cultivars. In the case of rice, the cultivar O. sativa ssp. japonica cv. Nipponbare has lower BTt and higher ATt, while the cultivar O. sativa ssp. aus cv. N22 has higher BTt. Antioxidant response, which includes non-enzymatic compounds (e.g. ascorbic acid and glutathione) and enzymatic (e.g. catalase and ascorbate peroxidase), plays a fundamental role in mitigating oxidative stress induced by heat stress in plants. Thus, evaluating antioxidant defense in response to heat stress in rice cultivars with different levels of thermotolerance is a relevant step in building a solid theoretical knowledge base for the development of heat-tolerant cultivars and maintaining global food security. In this context, this project aims to establish methodologies for the analysis of reactive oxygen species (hydrogen peroxide), enzymatic antioxidants (catalase, ascorbate peroxidase, and glutathione reductase), and non-enzymatic antioxidants (ascorbic acid and glutathione) in the rice cultivars Nipponbare and N22, with the objective of evaluating the effects of ATt and BTt on antioxidant defense and oxidative stress. The results obtained will allow the analysis of the relationship between antioxidant responses and the control of gene expression of the respective genes, which will be determined from the RNA-seq data produced by the "Auxílio Jovem Pesquisador" FAPESP grant (process 19/13158-8), to which this project is linked. Therefore, the generated data may greatly contribute to demonstrating the importance of transcriptional and post-transcriptional control in antioxidant response to heat in rice plants.