Low-nitrogen stress reduces cell flux and cell elongation rate in maize leaf via reducing GA synthesis
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ABSTRACT:
ORGANISM(S): Zea mays
PROVIDER: GSE99638 | GEO | 2020/06/01
REPOSITORIES: GEO
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Project description:One strategy for plants to adapt to low nitrogen (LN) stress is to reduce shoot growth and allocate more N and carbon for root growth. The physiological mechanism underlying the response of leaf growth to LN stress remains largely unknown. In this study, we investigated cell division and elongation in maize leaf growth in response to LN stress using an integrated approach including kinematic growth analysis, tissue-specific RNA-seq dissection and hormone determination.
2021-02-24 | GSE111425 | GEO
Project description:IntroductionIndividual leaves in the image are partly veiled by other leaves, which create shadows on another leaf. To eliminate the interference of soil and leaf shadows on cotton spectra and create reliable monitoring of cotton nitrogen content, one classification method to unmanned aerial vehicle (UAV) image pixels is proposed.MethodsIn this work, green light (550 nm) is divided into 10 levels to limit soil and leaf shadows (LS) on cotton spectrum. How many shadow has an influence on cotton spectra may be determined by the strong correlation between the vegetation index (VI) and leaf nitrogen content (LNC). Several machine learning methods were utilized to predict LNC using less disturbed VI. R-Square (R 2), root mean square error (RMSE), and mean absolute error (MAE) were used to evaluate the performance of the model.Results(i) after the spectrum were preprocessed by gaussian filter (GF), SG smooth (SG), and combination of GF and SG (GF&SG), the significant relationship between VI and LNC was greatly improved, so the Standard deviation of datasets was also decreased greatly; (ii) the image pixels were classified twice sequentially. Following the first classification, the influence of soil on vegetation index (VI) decreased. Following secondary classification, the influence of soil and LS to VI can be minimized. The relationship between the VI and LNC had improved significantly; (iii) After classifying the image pixels, the VI of 2-3, 2-4, and 2-5 have a stronger relationship with LNC accordingly. Correlation coefficients (r) can reach to 0.5. That optimizes monitoring performance when combined with GF&SG to predict LNC, support vector machine regression (SVMR) has the better performance, R 2, RMSE, and MAE up to 0.86, 1.01, and 0.71, respectively. The UAV image classification technique in this study can minimize the negative effects of soil and LS on cotton spectrum, allowing for efficient and timely predict LNC.
| S-EPMC11362076 | biostudies-literature
Project description:In terms of tillering potential, the aboveground portions of rice are significantly influenced by the nitrogen level (NL) and transplant density (TD). To obtain a suitable combination of NL and TD, five NLs (0, 90, 180, 270 and 360 kg ha-1) and two TDs [high density (HD), 32.5×104 hills ha-1; low density (LD), 25.5×104 hills ha-1] were used in the rice experiments during 2012 to 2014, in Jiangsu, China. The results showed the highest grain yield of rice obtained at HD and LD when N supply was 180 and 270 kg ha-1, respectively. That's because there are more tillers per unit area, a larger leaf biomass fraction of total aboveground biomass, a larger leaf area index (LAI) and a larger canopy photosynthesis potential (CPP) at HD. It can be concluded that, higher rice planting densities resulted in less N inputs, while more N is needed to improve single plant actual tiller ability under low density to offset the reduced planting density. When the NL was more than 180 kg ha-1, the actual tillering ability of a single plant at LD was 20% more than that at HD. Based on these results, the supply of 1 kg N can be replaced by adding approximately 1000 planting hills per hectare. Therefore, adjusting the transplant density could be an efficient method to reduce the amount of nitrogen fertilizer and increase the nitrogen fertilizer use efficiency, which is very conducive to the sustainable development of agriculture.
| S-EPMC5540556 | biostudies-literature
Project description:Arabidopsis leaf blades were sampled throughout development from meristematic through expanding to mature state at 10 different timepoints. The transcript data can be compared to a kinematic and flowcytometric characterisation of the system.
2004-09-20 | E-MEXP-144 | biostudies-arrayexpress
Project description:Plasticity of plant functional traits plays an important role in plant growth and survival under changing climate. However, knowledge about how leaf functional traits respond to the multi-level N addition rates, multiple N compound and duration of N application remains lacking. This study investigated the effects of 2-year and 7-year N addition on the leaf functional traits of Leymus chinensis and Thermopsis lanceolata in a meadow grassland. The results showed that the type of N compounds had no significant effect on leaf functional traits regardless of duration of N application. N addition significantly increased the leaf total N content (LN) and specific leaf area (SLA), and decreased the leaf total P content (LP) and leaf dry matter content (LDMC) of the two species. Compared with short-term N addition, long-term N addition increased LN, LP, SLA, and plant height, but decreased the LDMC. In addition, the traits of the two species were differentially responsive to N addition, LN and LP of T. lanceolata were consistently higher than those of L. chinensis. N addition would make L. chinensis and T. lanceolata tend to "quick investment-return" strategy. Our results provide more robust and comprehensive predictions of the effects of N deposition on leaf traits.
| S-EPMC8918929 | biostudies-literature
Project description:Plants have mutualistic symbiotic relationships with rhizobia and fungi by the common symbiosis pathway, of which Ca(2+)/calmodulin-dependent protein kinase (encoded by CCaMK) is a central component. Although Oryza sativa CCaMK (OsCCaMK) is required for fungal accommodation in rice roots, little is known about the role of OsCCaMK in rice symbiosis with bacteria. Here, we report the effect of a Tos17-induced OsCCaMK mutant (NE1115) on CH4 flux in low-nitrogen (LN) and standard-nitrogen (SN) paddy fields compared with wild-type (WT) Nipponbare. The growth of NE1115 was significantly decreased compared with that of the WT, especially in the LN field. The CH4 flux of NE1115 in the LN field was significantly greater (156 to 407% in 2011 and 170 to 816% in 2012) than that of the WT, although no difference was observed in the SN field. The copy number of pmoA (encodes methane monooxygenase in methanotrophs) was significantly higher in the roots and rhizosphere soil of the WT than in those of NE1115. However, the mcrA (encodes methyl coenzyme M reductase in methanogens) copy number did not differ between the WT and NE1115. These results were supported by a (13)C-labeled CH4-feeding experiment. In addition, the natural abundance of (15)N in WT shoots (3.05‰) was significantly lower than in NE1115 shoots (3.45‰), suggesting greater N2 fixation in the WT because of dilution with atmospheric N2 (0.00‰). Thus, CH4 oxidation and N2 fixation were simultaneously activated in the root zone of WT rice in the LN field and both processes are likely controlled by OsCCaMK.
| S-EPMC3957643 | biostudies-literature
Project description:Early leaf growth is sustained by cell proliferation and subsequent cell expansion that initiates at the leaf tip and proceeds in a basipetal direction. Using detailed kinematic and gene expression studies to map these stages during early development of the third leaf of Arabidopsis thaliana we showed that the cell cycle arrest front did not progress gradually down the leaf, but rather was established and abolished abruptly. Interestingly, leaf greening and stomatal patterning followed a similar basipetal pattern, but proliferative pavement cell and formative meristemoid divisions were uncoordinated in respect to onset and persistence. Genes differentially expressed during the transition from cell proliferation to expansion were enriched in genes involved in cell cycle, photosynthesis, and chloroplast retrograde signaling. Proliferating primordia treated with norflurazon, a chemical inhibitor of retrograde signaling, showed inhibited onset of cell expansion. Hence, differentiation of the photosynthetic machinery is important for regulating the exit from proliferation.
2012-01-17 | GSE33936 | GEO
Project description:Coordinated functioning of the cob and florets of the maize ear confers grain yield. However, comprehensive molecular differentiation of the cob and florets and their responses to low nitrogen (LN) stress remain elusive. We compared transcriptional profiles of the cob and peripheral florets of a maize hybrid at the silking stage at two N levels in the field and found 1,864 differentially expressed genes between the cob and florets, with 1314 genes up-regulated in the cob and 550 genes up-regulated in florets. The cob was featured by preferential expression of 161 genes, with striking enrichment of genes that are involved in transport facilitation and energy metabolism, consistent with the physiological role of the cob in C/N storage and transfer during ear development. The florets were characteristic of preferential expression of 108 genes, with enrichment of genes that are involved in the cellular process and lipid biosynthetic process. LN caused differential expression of 588 genes in the cob and only 195 genes in florets, indicating that the cob dominated the response of the ear to LN at the transcriptional level. Differentially expressed genes under LN were involved in C/N metabolism, transcriptional regulation, development, cell rescue and defense, and signal transduction in the cob and/or florets. The expression level of 106 genes was regulated by LN in both tissues, suggesting a common regulatory network in these two functionally distinct tissues under LN. Compared with P or K deficiency, LN specifically caused differential expression of 14 genes, revealing unique biological consequences in the ear caused by N limitation at a critical reproductive stage. Collectively, our studies identified unique transcriptomic signatures of the cob and florets, revealed the dominance of the cob in response to LN at the silking stage, and provided molecular markers for N nutritional diagnosis and N efficient maize breeding.
2015-07-19 | GSE59613 | GEO
Project description:Elucidating the effects of atmospheric nitrogen (N) deposition on the photosynthetic capacity of plants is critical to understand forest growth and conservation under global change. However, studies on this topic generally consider only understory N addition, which ignores the effect of canopy interception. In this study, we conducted a field experiment in a subtropical forest to compare the effects of canopy vs. understory N addition on the photosynthetic rate of canopy and understory species. We found that canopy N addition enhanced the photosynthetic rate of canopy species by increasing leaf hydraulic conductivity and shortening the distance of CO2 transportation. In contrast, understory N addition had non-significant effects on the photosynthetic rate of canopy species. Moreover, the photosynthetic rate of understory species was not affected by canopy or understory N addition. Interestingly, changes in hydraulic conductivity contributed more to accelerating the photosynthetic rate than changes in CO2 transport distance. Our results provide important insights into the dissimilar effects of canopy and understory N addition on the photosynthetic rates of species in subtropical forests. Based on our findings, we highlighted the urgent need to consider canopy processes in future studies on N deposition.
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Project description:Reactive nitrogen (N) is created in order to sustain food production, but only a small fraction of this N ends up being consumed as food, the rest being lost to the environment. We calculated that the total N input (TN) of global food production was 171 Tg N yr(-1) in 2000. The production of animal products accounted for over 50% of the TN, against 17% for global calories production. Under current TN per unit of food production and assuming no change in agricultural practices and waste-to-food ratios, we estimate that an additional TN of 100 Tg N yr(-1) will be needed by 2030 for a baseline scenario that would meet hunger alleviation targets for over 9 billion people. Increased animal production will have the largest impact on increasing TN, which calls for new food production systems with better N-recycling, such as cooperation between crop and livestock producing farms. Increased N-use efficiency, healthier diet and decreased food waste could mitigate this increase and even reduce TN in 2030 by 8% relative to the 2000 level. Achieving a worldwide reduction of TN is a major challenge that requires sustained actions to improve nitrogen management practices and reduce nitrogen losses into the environment.
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