Urea in Plants: Metabolic Aspects and Ecological Implications

Matiz, Alejandra; Mioto, Paulo Tamaso; Mercier, Helenice

doi:10.1007/124_2019_29

Cited by 3 publications

(2 citation statements)

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“…It is well known that abiotic stresses, such as drought, induce stomata closure and, consequently, limit uptake of atmospheric CO 2 into the leaf tissue (Chen et al, 2018;Gobara et al, 2020). In this context, urea hydrolysis through foliar urease activity may partially compensate for the CO 2 reduction by providing it, in addition to NH 4 + (Matiz et al, 2017(Matiz et al, , 2019. This mechanism may represent an important physiological adaptation to obtain C and N at the same time.…”

Section: Urea Can Positively Modulate C3-cam Shift Under Water Deficitmentioning

confidence: 99%

“…For G. monostachia, urea and NH 4 + are the preferred N forms of uptake (Gonçalves et al, 2020b). The absorption of urea as a whole molecule took place mainly at the basal region of the leaf through the transporters of low (TIP2.1) and high (DUR 3) affinity and may be stored in the vacuole before the water deficit imposition (Matiz et al, 2019;Gonçalves et al, 2020b). If we consider the CAM-idling photosynthetic mode, whose gas exchange with the atmosphere largely ceases and respiration provides the CO 2 (Winter, 2019), this strategy of using urea as a preferential source of N becomes even more relevant.…”

Section: Urea Can Positively Modulate C3-cam Shift Under Water Deficitmentioning

confidence: 99%

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Transcriptomic and Biochemical Analysis Reveal Integrative Pathways Between Carbon and Nitrogen Metabolism in Guzmania monostachia (Bromeliaceae) Under Drought

Gonçalves

Mercier

2021

Front. Plant Sci.

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Most epiphytes are found in low-nutrient environments with an intermittent water supply. To deal with water limitation, many bromeliads perform crassulacean acid metabolism (CAM), such as Guzmania monostachia, which shifts from C3 to CAM and can recycle CO2 from the respiration while stomata remain closed during daytime and nighttime (CAM-idling mode). Since the absorbing leaf trichomes can be in contact with organic (urea) and inorganic nutrients (NO3−, NH4+) and the urea hydrolysis releases NH4+ and CO2, we hypothesized that urea can integrate the N and C metabolism during periods of severe drought. Under this condition, NH4+ can be assimilated into amino acids through glutamine synthetase (GS), while the CO2 can be pre-fixated by phosphoenolpyruvate carboxylase (PEPC). In this context, we evaluated the foliar transcriptome of G. monostachia to compare the relative gene expression of some genes involved with CAM and the N metabolism when bromeliads were submitted to 7days of drought. We also conducted a controlled experiment with an extended water deficit period (21days) in which bromeliads were cultivated in different N sources (urea, NH4+, and NO3−). Our transcriptome results demonstrated an increment in the expression of genes related to CAM, particularly those involved in the carboxylation metabolism (PEPC1, PPCK, and NAD-MDH), the movement of malate through vacuolar membrane (ALMT9), and the decarboxylation process (PEPCK). Urea stimulated the expression of PEPC1 and ALMT9, while Urease transcripts increased under water deficit. Under this same condition, GS1 gene expression increased, indicating that the NH4+ from urea hydrolysis can be assimilated in the cytosol. We suggest that the link between C and N metabolism occurred through the supply of carbon skeleton (2-oxoglutarate, 2-OG) by the cytosolic isocitrate dehydrogenase since the number of NADP-ICDH transcripts was also higher under drought conditions. These findings indicate that while urea hydrolysis provides NH4+ that can be consumed by glutamine synthetase-cytosolic/glutamate synthase (GS1/GOGAT) cycle, the CO2 can be used by CAM, maintaining photosynthetic efficiency even when most stomata remain closed 24h (CAM-idling) as in the case of a severe water deficit condition. Thus, we suggest that urea could be used by G. monostachia as a strategy to increase its survival under drought, integrating N and C metabolism.

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Section: Urea Can Positively Modulate C3-cam Shift Under Water Deficitmentioning

confidence: 99%

Section: Urea Can Positively Modulate C3-cam Shift Under Water Deficitmentioning

confidence: 99%

Transcriptomic and Biochemical Analysis Reveal Integrative Pathways Between Carbon and Nitrogen Metabolism in Guzmania monostachia (Bromeliaceae) Under Drought

Gonçalves

Mercier

2021

Front. Plant Sci.

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The urea transporter DUR3 is differentially regulated by abiotic and biotic stresses in coffee plants

Santos

Baba

Vieira

et al. 2021

Physiol Mol Biol Plants

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The high costs of N fertilizers in the coffee production emphasizes the need to optimize fertilization practices and improve nitrogen use efficiency. Urea is widespread in nature, characterizing itself as a significant source of nitrogen for the growth and development of several organisms. Thus, the characterization of genes involved in urea transport in coffee plants is an important research topic for the sustainable production of this valuable cash crop. In the current study, we evaluated the expression of the DUR3 gene under abiotic and biotic stresses in coffee plants. Here, we show that the expression of a high-affinity urea transporter gene (CaDUR3) was upregulated by N starvation in leaves and roots of two out of three C. arabica cultivars examined. Moreover, the CaDUR3 gene was differentially expressed in coffee plants under different abiotic and biotic stresses. In plants of cv. IAPAR59, CaDUR3 showed an increased expression in leaves after exposure to water deficit and heat stress, while it was downregulated in plants under salinity. Upon infection with H. vastatrix (coffee rust), the CaDUR3 was markedly up-regulated at the beginning of the infection process in the disease susceptible Catuaı ´Vermelho 99 in comparison with the resistant cultivar. These results indicate that besides urea acquisition and N-remobilization, CaDUR3 gene may be closely involved in the response to various stresses.

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