Nitrogen Fertilizer Regulated Grain Storage Protein Synthesis and Reduced Chalkiness of Rice Under Actual Field Warming

Abstract

Our previous study has shown that nitrogen plays an important role in dealing with significantly increased chalkiness caused by elevated temperature. However, the role of nitrogen metabolites has not been given sufficient attention, and its regulatory mechanism is not clear. This study investigated the effects of high temperature and nitrogen fertilizer on the synthesis of grain storage protein and further explored the quality mechanism under the actual scenario of field warming. Results showed that increased temperature and nitrogen fertilizer could affect the activities of nitrogen metabolism enzymes, namely, glutamate synthetase, glutamine synthetase, glutamic pyruvic transaminase, and glutamic oxaloacetic transaminase, and the expressions of storage protein synthesis factor genes, namely, GluA and GluB, and subfamily genes, namely, pro14, BiP1, and PDIL1, which co-induced the changes of storage protein synthesis in rice grains. Furthermore, the increased temperature changed the balance of grain storage substances which may lead to the significantly increased chalky rate (197.67%) and chalkiness (532.92%). Moreover, there was a significant negative correlation between prolamin content and chalkiness, indicating that nitrogen fertilizer might regulate the formation of chalkiness by affecting the synthesis of prolamin. Results suggested that nitrogen application could regulate the related core factors involved in nitrogen metabolism pathways, which, in turn, affects the changes in the storage protein components in the grain and further affects quality. Therefore, as a conventional cultivation measure, nitrogen application would have a certain value in future rice production in response to climate warming.

Effects of Wx Genotype, Nitrogen Fertilization, and Temperature on Rice Grain Quality

“…This might be due to the different timing and management of nitrogen application (Zhu et al, 2016(Zhu et al, , 2017Zhao et al, 2020;Hu et al, 2021;Ning et al, 2021). A slight improvement in appearance quality in lines with highly expressed Wx alleles was observed with increased nitrogen at higher temperatures, which was consistent with a previous report (Wang et al, 2021). However, this decrease in CR and CD was not found at LT (Figures 3D-F, 5B and Table 3), suggesting the pivotal role of HTs and mutual effect among temperature, nitrogen fertilization, and Wx genotype on chalkiness formation.…”

“…However, this decrease in CR and CD was not found at LT (Figures 3D-F, 5B and Table 3), suggesting the pivotal role of HTs and mutual effect among temperature, nitrogen fertilization, and Wx genotype on chalkiness formation. It is generally agreed that HT induces the formation of chalky grains and reduces appearance and milling qualities (Counce et al, 2005;Zhang et al, 2016;Wang et al, 2021;. In the present study, we found that both CR and CD were higher under the higher temperature conditions and transparency decreased (Figures 4A,I-K).…”

Characteristics of Seed Vigor in Rice Varieties with Different Globulin Accumulations

“…Whether globulin is involved in the regulation of seed development is still unclear. Previously, it has been reported that protein content is negatively correlated with grain chalkiness [ 21 , 22 , 23 ]. The negative correlation between globulin content and chalkiness was also observed in this study.…”

Grain Quality Affected by Introducing Photorespiratory Bypasses into Rice

“…Carbon and nitrogen metabolisms are crucial to both the yield and quality of rice grains, and their products contained in starch and proteins account for nearly 87% of the dry matter in brown rice [16]. Nitrogen is a crucial nutrient, and applying nitrogen fertilizers is an important management factor that affects both grain yield and quality [17][18][19]. However, more than 50% of nitrogen fertilizers applied to the field have not been absorbed and utilized by crops and consequently cause soil acidification and environmental pollution, which seriously threaten humans' health [20].…”