Abstract
BackgroundThe crop growth compensation effect is a naturally biological phenomenon, and nitrogen (N) is essential for crop growth and development, especially for yield formation. Little is known about the molecular mechanism of N deficiency and N compensation in rice. Thus, the N-sensitive stage of rice was selected to study N deficiency at the tillering stage and N compensation at the young panicle differentiation stage. In this study, a proteome analysis was performed to analyze leaf differentially expressed proteins (DEPs), and to investigate the leaf physiological characteristics and yield under N deficiency and after N compensation.ResultsThe yield per plant presented an equivalent compensatory effect. The net photosynthetic rate, optimal/maximal quantum yield of photosystem II (Fv/Fm), soil and plant analyzer development (SPAD) value, and glutamic pyruvic transaminase (GPT) activity of T1 (N deficiency at the tillering stage, and N compensation at the young panicle differentiation stage) were lower than those of CK (N at different stages of growth by constant distribution) under N deficiency. However, after N compensation, the net photosynthetic rate, Fv/Fm, SPAD value and GPT activity were increased. Using an iTRAQ-based quantitative approach, a total of 1665 credible proteins were identified in the three 4-plex iTRAQ experiments. Bioinformatics analysis indicated that DEPs were enriched in photosynthesis, photosynthesis-antenna proteins, carbon metabolism and carbon fixation in the photosynthetic organism pathways. Moreover, the photosynthesis-responsive proteins of chlorophyll a-b binding protein, ribulose bisphosphate carboxylase small chain and phosphoglycerate kinase were significantly downregulated under N deficiency. After N compensation, chlorophyll a-b binding protein, NADH dehydrogenase subunit 5, NADH dehydrogenase subunit 7, and peroxidase proteins were significantly upregulated in rice leaves.ConclusionThrough physiological and quantitative proteomic analysis, we concluded that a variety of metabolic pathway changes was induced by N deficiency and N compensation. GO and KEGG enrichment analysis revealed that DEPs were significantly associated with photosynthesis pathway-, energy metabolism pathway- and stress resistance-related proteins. The DEPs play an important role in the regulation of N deficiency and the compensation effect in rice.
Highlights
The crop growth compensation effect is a naturally biological phenomenon, and nitrogen (N) is essential for crop growth and development, especially for yield formation
The “Tri-control” fertilization technology system emphasizes the proportion of N fertilizer and delaying the application time at the tillering stage should be reduced and the proportion of N fertilizer at the panicle differentiation stage should be increased to ensure high and stable yield of rice [35]
Using the criteria of Score Sequest HT > 0 and Unique peptides ≥1 and removing the blank value, the results showed that 2016 credible proteins were screened from Isobaric tags for relative and absolute quantification (iTRAQ) the results of experiment 1, 2134 credible proteins were screened from iTRAQ the results of experiment 2, and 2168 credible proteins were screened from iTRAQ the results of experiment 3
Summary
The crop growth compensation effect is a naturally biological phenomenon, and nitrogen (N) is essential for crop growth and development, especially for yield formation. Elemental nitrogen (N) is one of the main elements of amino acids, chlorophyll, nucleic acids, lipids and many intermediate metabolites. It plays an important role in plant growth and agricultural production [1, 2]. The irrational use of N fertilizer increases the cost of production and has negative effects on soil microorganisms, plants, animals and the environment itself [8]. The yield formation mechanism of N deficiency and the compensation effect in rice is worthy of in-depth research. This subject has important significance for balancing ecological environment protection, high yield and stable yield of crops
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