Effect of high temperature stress on metabolome and aroma in rice grains

Abstract

Heat stress poses a significant challenge to global rice production, affecting yield and grain quality. Elevated temperatures during the flowering and grain-filling stages, both day and night, lead to reduced yield and compromised grain quality. This impact is more pronounced during nighttime high-temperature stress, seriously threatening rice productivity. With global temperatures rising, there is a looming threat to rice production. Aromatic rice, prized for superior aroma and grain quality, is particularly vulnerable to heat. Therefore, the present work has been carried out to investigate how high temperature affects the aromatic metabolites in rice grains among the 15 rice genotypes (fourteen aromatic and one non-aromatic rice i.e., Nagina 22). Results from the present study indicated that the inactive (mutated) BADH2 gene expression was down-regulated under high-temperature stress conditions and no 2-acetyl-1-pyrroline (2-AP) accumulation was detected in the selected rice genotypes. However, the increase in levels of L-proline (precursor molecule for 2-AP) was detected, and due to the down-regulation of inactive BADH2, the oxidation of L-proline into 2-AP was affected. Proline amino acid significantly increased under high temperatures, impacting aroma quality. Metabolome studies revealed variations in compound detection among scented rice genotypes. Understanding these metabolites aids in addressing the loss of aroma in fragrant rice genotypes, offering insights into developing stable aromatic rice varieties under elevated temperature conditions. The study aims to identify metabolites causing aroma loss in aromatic rice. Results will aid in understanding aroma depletion mechanisms in scented rice under high-temperature stress, guiding the development of a stable aromatic rice variety in elevated temperatures.