Can genetic manipulation of plant nitrogen assimilation enzymes result in increased crop yield and greater N-use efficiency? An assessment

• Published in: Annals of applied biology Vol. 145; no. 1; pp. 25 - 40
• Main Authors: Andrews, M, Lea, P.J, Raven, J.A, Lindsey, K
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2004; Blackwell
• Subjects: ammonium assimilation; ammonium compounds; assimilation (physiology); biochemical pathways; Biological and medical sciences; crop yield; crops; enzyme activity; Fundamental and applied biological sciences. Psychology; genetic engineering; genetic manipulation; glutamate synthase; glutamate synthase (NADH); glutamate-ammonia ligase; glutamine synthetase; literature reviews; nitrate assimilation; nitrate reductase; nitrates; nitrite reductase; nitrogen; Nitrogen assimilation; nitrogen metabolism; nitrogen use efficiency; nutrient use efficiency; Oryza sativa; plant growth; plants; rice; Assimilation; Plant production; genetic manipulation; Carbon-nitrogen ligases; nitrogen use efficiency; Enzyme; Nitrite reductase; Nutrient recovery; Biology; glutamate synthase; Synthase; Nitrogen; Glutamate; Nitrogen assimilation; crop yield; Ligases; Nitrate reductase; glutamine synthetase; Genetic engineering; Yield; Oxidoreductases; Glutamate-ammonia ligase; Applied research
• ISSN: 0003-4746; 1744-7348
• DOI: 10.1111/j.1744-7348.2004.tb00356.x

Summary The literature on the relations between plant nitrogen (N) assimilation enzymes and plant/crop N assimilation, growth and yield is reviewed to assess if genetic manipulation of the activities of N assimilation enzymes can result in increased yield and/or increased N use efficiency. The available data indicate that (I) levels of N assimilation enzymes do not limit primary N assimilation and hence yield; (II) root or shoot nitrate assimilation can have advantages under specific environmental conditions; (III) for cereals, cytosolic glutamine synthetase (GS1) is a key enzyme in the mobilisation of N from senescing leaves and its activity in senescing leaves is positively related to yield; and (TV) for rice (Oryza sativd), NADH‐glutamate synthase (NADH‐GOGAT) is important in the utilisation of N in grain filling and its activity in developing grains is positively related to yield. In our opinion, selection of plants, from either a genetically manipulated population or genetic resources, with expression of nitrate reductase/nitrite reductase primarily in the root or shoot should increase plant/crop growth and hence yield under specific environmental conditions. In addition for cereals the selection of plants with high GS1 in senescing leaves and in some cases high NADH‐GOGAT in developing grains could help maximise the retrieval of plant N in seeds.