Impact of elevated temperature stress on aroma and its gene expression in photosensitive Basmati Rice

Abstract

Creation of aromatic rice with prevalent agronomic execution and brilliant fragrance is confounded because of the impacts of ecological elements, social practice and genotypic condition. Among the natural factors, the temperature is one of the most significant elements that can influence development, improvement, and creation of aromatic rice just as the nature of fragrance expression. In this manner, choice of appropriate growth stage and assurance of an appropriate temperature for expression of aroma quality is a significant determinant for great aromatic rice development. This study assessed the effects of different temperatures (early, normal and late sown condition) for relative expression of badh2 and p5cs gene, 2AP (2- acetyl -1- pyrroline) concentration, proline and amylose content as well as morpho-agronomic performance of photosensitive basmati rice variety Basmati 370. The results indicated that higher temperature does not favour rapid the grain filling; favours early maturity; favours 1000 grain weight, reduced the kernel length as well as the grain yield per plant significantly. However the amylose content was higher in the early sown than the normal and late sown condition. The relative expression of the badh2 gene had an inverse relation with the 2AP production so more the down regulation of the badh2 gene higher was the production of the 2AP in all the developmental stages in Basmati 370. In contrast the p5cs gene expression shared a direct relation with the proline production, more the up regulation of the p5cs gene more was the production of the proline content in all the developmental stages. It can also be concluded that the temperature had a tremendous affect on the gene expression of the badh2 and the p5cs genes. The expression of badh2 gene was masked more in the higher temperatures in the seedling and flowering stages. The p5cs gene expression increased when the average temperature was high in the seedling stage, while it was more up regulated when the temperature was low in the flowering and grain filling stages. Consequently, the 2AP concentration increased in the early sown condition than the late sown condition in seedling and flowering stages while it was similar in the grain filling stage. The proline content increased in the early sown condition in the seedling and flowering stages while it was more in the late sown condition than the earl sown condition in the grain filling stage. This investigation also revealed that the relationship between the proline content and 2AP concentration varied in all the developmental stages in the early as well as in the late sown conditions. Temperature affects the agronomic performance, expression of aroma gene, the proline and amylose content, as well as the production of 2AP. Therefore, when the photosensitive basmati rice variety Basmati 370 was sown earlier or later than the normal sown condition then the aroma content was not much variable during the grain filling stage while it was low in the seedling and flowering stages in the late sown condition than the normal sown condition. This can be attributed to more down regulation of the expression of badh2 gene in the gran filling stage and higher expression of p5cs gene in the seedling stage as a consequence the 2AP and proline production varied. In the early and late sown conditions although the aroma content increased but the grain yield, grain weight and the kernel length was compromised.. The obtained information will be helpful for exploring possible reasons for variation in the biochemical composition as well as aroma quality of a genotype which might be used to further improve grain quality of aromatic rice.