Nitrogen Alleviated the Deterioration of Rice Quality by Affecting the Accumulation of Grain Storage Protein Under Elevated Temperature

The adverse effect of future global warming on rice quality is a fact that cannot be ignored. Evidence from our previous field warming experiments confirmed that warming had a significant negative impact on rice appearance and processing quality during the grain-filling stage. Therefore, clarifying the regulation mechanism of cultivation measures on the formation of quality under elevated temperature and formulating countermeasures to ensure the production of high-quality rice are of great significance in the future. As a cultivation measure that is easy to operate in the field, nitrogen has been shown to be effective in mitigating the quality deterioration induced by field warming in our previous study. In this study, results of actual field warming and nitrogen treatments showed that nitrogen mainly dominated grain nitrogen metabolism under elevated temperature, further affecting the composition and proportion of grain storage proteins. Furthermore, nitrogen significantly up-regulated the expression of GluA-1, pro14 and pro17 in protein synthesis and PDIL1-1 in protein processing pathway under elevated temperature, which further alleviated the decrease of prolamin content and enhanced the glutelin content. The transcriptional regulation of storage protein synthesis genes by nitrogen further induced the changes of storage substances, which will help us to further analyze the formation mechanism of rice quality under elevated temperature and provide a basis for the establishment of rational nitrogen regulation pathways for high-quality rice production under global warming in the future.