A Natural Light/Dark Cycle Regulation of Carbon-Nitrogen Metabolism and Gene Expression in Rice Shoots

Abstract

Light and temperature are two particularly important environmental cues for plant survival. Carbon and nitrogen are two essential macronutrients required for plant growth and development, and cellular carbon and nitrogen metabolism must be tightly coordinated. In order to understand how the natural light/dark cycle regulates carbon and nitrogen metabolism in rice plants, we analyzed the photosynthesis, key carbon-nitrogen metabolites, and enzyme activities, and differentially expressed genes and miRNAs involved in the carbon and nitrogen metabolic pathway in rice shoots at the following times: 2:00, 6:00, 10:00, 14:00, 18:00, and 22:00. Our results indicated that more CO2 was fixed into carbohydrates by a high net photosynthetic rate, respiratory rate, and stomatal conductance in the daytime. Although high levels of the nitrate reductase activity, free ammonium and carbohydrates were exhibited in the daytime, the protein synthesis was not significantly facilitated by the light and temperature. In mRNA sequencing, the carbon and nitrogen metabolism-related differentially expressed genes were obtained, which could be divided into eight groups: photosynthesis, TCA cycle, sugar transport, sugar metabolism, nitrogen transport, nitrogen reduction, amino acid metabolism, and nitrogen regulation. Additionally, a total of 78,306 alternative splicing events have been identified, which primarily belong to alternative 5′ donor sites, alternative 3′ acceptor sites, intron retention, and exon skipping. In sRNA sequencing, four carbon and nitrogen metabolism-related miRNAs (osa-miR1440b, osa-miR2876-5p, osa-miR1877 and osa-miR5799) were determined to be regulated by natural light/dark cycle. The expression level analysis showed that the four carbon and nitrogen metabolism-related miRNAs negatively regulated their target genes. These results may provide a good strategy to study how natural light/dark cycle regulates carbon and nitrogen metabolism to ensure plant growth and development.

Nitrogen uptake and assimilation in proliferating embryogenic cultures of Norway spruce—Investigating the specific role of glutamine

“…Assimilation of inorganic N requires a supply of C-skeletons, indicative of the close correlation between C- and N-metabolism [ 61 – 64 ]. In a non-photosynthetic tissue culture system, C-skeletons and energy are commonly provided as sucrose in the media.…”

“…Although NO 3 - -derived N comprised 26% of the total N uptake, NO 3 - -N accounted for only 10% of the free AA pool ( Fig 5 ). This may be the result of NO 3 - remaining in the intercellular space, low capacity for nitrate and nitrite reduction, and/or storage of NO 3 - in vacuole [ 39 , 64 ]. Alternatively, low incorporation of NO 3 - could indicate low GS activity.…”

Heterodera schachtii infection affects nitrogen metabolism in Arabidopsis thaliana

“…It plays an essential role in seedling development and promotes photomorphogenesis in response to light signals (Abbas et al , ). Nitrogen compound (, ) uptake, assimilation, and metabolism are dependent on light, and their behaviour is significantly regulated by the circadian clock (Li et al , ). Interestingly, HY5 positively regulates gene expression of nitrate and nitrite reductases in A. thaliana (Huang et al , ).…”

Biosensor-Mediated In Situ Imaging Defines the Availability Period of Assimilatory Glutamine in Maize Seedling Leaves Following Nitrogen Fertilization

“…The 24 h time-frame of Gln (and nitrate, ammonia) availability at a N sink may have implications for our understanding of N metabolism. It is well known that N uptake and assimilation genes, enzymes and metabolites such as Gln are under circadian control [25,26,33]. However, it may be that plants regulate the availability period of free Gln not because it is an intermediate to build other N-containing molecules-in this role, it may be advantageous for free Gln to persist locally.…”