Over-expression of the rice OsAMT1-1 gene increases ammonium uptake and content, but impairs growth and development of plants under high ammonium nutrition

Hoque, Mohammad Shamsul; Masle, Josette; Udvardi, Michael K.; Ryan, Peter R.; Upadhyaya, Narayana M.

doi:10.1071/fp05165

Cited by 80 publications

(36 citation statements)

References 33 publications

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“…3C). A recent analysis of transgenic rice (Oryza sativa) plants overexpressing OsAMT1;1 reported an increased rate of ammonium depletion from the nutrient solution and increased ammonium concentrations in roots and shoots when expressed per unit fresh weight (Hoque et al, 2006). These indications for increased ammonium uptake, however, were accompanied by lower biomass production, so that it remained unclear whether roots of these lines really possess an enhanced capacity for ammonium uptake.…”

Section: Discussion Ectopic Expression Of Atamt1;1 In Tobacco Confersmentioning

confidence: 99%

Nitrogen-Dependent Posttranscriptional Regulation of the Ammonium Transporter AtAMT1;1

et al. 2006

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Ammonium transporter (AMT) proteins of the AMT family mediate the transport of ammonium across plasma membranes. To investigate whether AMTs are regulated at the posttranscriptional level, a gene construct consisting of the cauliflower mosaic virus 35S promoter driving the Arabidopsis (Arabidopsis thaliana) AMT1;1 gene was introduced into tobacco (Nicotiana tabacum). Ectopic expression of AtAMT1;1 in transgenic tobacco lines led to high transcript levels and protein levels at the plasma membrane and translated into an approximately 30% increase in root uptake capacity for 15 N-labeled ammonium in hydroponically grown transgenic plants. When ammonium was supplied as the major nitrogen (N) form but at limiting amounts to soil-grown plants, transgenic lines overexpressing AtAMT1;1 did not show enhanced growth or N acquisition relative to wild-type plants. Surprisingly, steady-state transcript levels of AtAMT1;1 accumulated to higher levels in N-deficient roots and shoots of transgenic tobacco plants in spite of expression being controlled by the constitutive 35S promoter. Moreover, steady-state transcript levels were decreased after addition of ammonium or nitrate in N-deficient roots, suggesting a role for N availability in regulating AtAMT1;1 transcript abundance. Nitrogen deficiency-dependent accumulation of AtAMT1;1 mRNA was also observed in 35S:AtAMT1;1-transformed Arabidopsis shoots but not in roots. Evidence for a regulatory role of the 3#-untranslated region of AtAMT1;1 alone in N-dependent transcript accumulation was not found. However, transcript levels of AtAMT1;3 did not accumulate in a N-dependent manner, even though the same T-DNA insertion line atamt1;1-1 was used for 35S:AtAMT1;3 expression. These results show that the accumulation of AtAMT1;1 transcripts is regulated in a N-and organ-dependent manner and suggest mRNA turnover as an additional mechanism for the regulation of AtAMT1;1 in response to the N nutritional status of plants.

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Section: Discussion Ectopic Expression Of Atamt1;1 In Tobacco Confersmentioning

confidence: 99%

Nitrogen-Dependent Posttranscriptional Regulation of the Ammonium Transporter AtAMT1;1

et al. 2006

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“…It has been reported that OsAMT1;1, showing a higher expression level in roots under ammonium supply, contributes to NH 4 + uptake and plays an important role in NK homeostasis [48,[50][51][52]. OsAMT1;2 showed root-specific expression, is induced by ammonium, and may function as a nitrogen assimilator [49,53].…”

Section: Nitrogen Acquisitionmentioning

confidence: 95%

Nitrogen Use Efficiency in Rice

Huang¹,

Zhao²,

Zhang³

et al. 2018

Nitrogen in Agriculture - Updates

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Food security is a major global issue because of the growing population and decreasing land area. Rice (Oryza sativa L.) is the most important staple cereal crop in the world. Application of nitrogen (N) fertilizer has improved crop yield in the world during the past five decades but with considerable negative impacts on the environment. New solutions are therefore urgently needed to simultaneously increase yields while maintaining or preferably decreasing applied N to maximize the nitrogen use efficiency (NUE) of crops. Plant NUE is inherently complex with each step (including N uptake, translocation, assimilation, and remobilization) governed by multiple interacting genetic and environmental factors. Based on the current knowledge, we propose some possible approaches enhancing NUE, by molecular manipulation selecting candidate genes and agricultural integrated management practices for NUE improvement. Developing an integrated research program combining approaches, mainly based on whole-plant physiology, quantitative genetics, forward and reverse genetics, and agronomy approaches to improve NUE, is a major objective in the future.

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“…To date, the three OsAMT1 genes have been most studied, and found to be significantly or predominantly expressed in the roots (Kumar et al 2003;Sonoda et al 2003a). Overexpression of OsAMT1.1 sometimes resulted in an enhanced NH 4 + influx in the roots, depending on genotype background and experimental conditions, thus supporting its role in NH 4 + acquisition by the plant (Hoque et al 2006;Kumar et al 2006). However, OsAMT1.1 overexpressors often show reduced growth as compared to wildtype plants when supplied with NH 4 + as sole N source, possibly indicating toxicity effects of excessive NH 4 + intake (Hoque et al 2006;Kumar et al 2006).…”

Section: Ammonium Transportersmentioning

confidence: 99%

Nitrogen acquisition by roots: physiological and developmental mechanisms ensuring plant adaptation to a fluctuating resource

2013

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Background Nitrogen (N) is one of the key mineral nutrients for plants and its availability has a major impact on their growth and development. Most often N resources are limiting and plants have evolved various strategies to modulate their root uptake capacity to compensate for both spatial and temporal changes in N availability in soil. The main N sources for terrestrial plants in soils of temperate regions are in decreasing order of abundance, nitrate, ammonium and amino acids. N uptake systems combine, for these different N forms, high-and low-affinity transporters belonging to multige families. Expression and activity of most uptake systems are regulated locally by the concentration of their substrate, and by a systemic feedback control exerted by whole-plant signals of N status, giving rise to a complex combinatory network. Besides modulation of the capacity of transport systems, plants are also able to modulate their growth and development to maintain N homeostasis. In particular, root system architecture is highly plastic and its changes can greatly impact N acquisition from soil.Scope In this review, we aim at detailing recent advances in the identification of molecular mechanisms responsible for physiological and developmental responses of root N acquisition to changes in N availability. These mechanisms are now unravelled at an increasing rate, especially in the model plant Arabidopsis thaliana L.. Within the past decade, most root membrane transport proteins that determine N acquisition have been identified. More recently, molecular regulators in nitrate or ammonium sensing and signalling have been isolated, revealing common regulatory genes for transport system and root development, as well as a strong connection between N and hormone signalling pathways. Conclusion Deciphering the complexity of the regulatory networks that control N uptake, metabolism and plant development will help understanding adaptation of plants to sub-optimal N availability and fluctuating environments. It will also provide solutions for addressing the major issues of pollution and economical costs related to N fertilizer use that threaten agricultural and ecological sustainability.

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Over-expression of the rice OsAMT1-1 gene increases ammonium uptake and content, but impairs growth and development of plants under high ammonium nutrition

Cited by 80 publications

References 33 publications

Nitrogen-Dependent Posttranscriptional Regulation of the Ammonium Transporter AtAMT1;1

Nitrogen-Dependent Posttranscriptional Regulation of the Ammonium Transporter AtAMT1;1

Nitrogen Use Efficiency in Rice

Nitrogen acquisition by roots: physiological and developmental mechanisms ensuring plant adaptation to a fluctuating resource

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