Exploiting genetic variation in nitrogen use efficiency for cereal crop improvement

Highlights

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  A statement on the critical importance of this area of plant science in terms of food security and sustainability.

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  An outline of the critical NUE processes and example studies of identified variation in the complex trait of nitrogen use efficiency.

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  Reference to number of critical single key genes/alleles which have major impacts on NUE.

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  A description of the most useful genetic approaches being utilised to breed for NUE in cereals.

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  Future prospects on the most important areas and approaches likely to have impact.

Abstract

Cereals are the most important sources of calories and nutrition for the human population, and are an essential animal feed. Food security depends on adequate production and demands are predicted to rise as the global population rises. The need for increased yields will have to be coupled to the efficient use of resources including fertilisers such as nitrogen to underpin the sustainability of food production. Although optimally performing crops with high yields require a balanced mineral nutrition, nitrogen fundamentally drives growth and yield as well as requirements for other nutrients. It is estimated that globally only 33% of applied nitrogen fertiliser is recovered in the harvested grain, indicative of a huge waste of resource and potential major pollutant and is thus a major target for crop improvement. Both agronomy and breeding will contribute to improved nitrogen use efficiency (NUE) and an important component of the latter is harnessing germplasm variation. This review will consider the key traits involved in NUE, the potential to exploit genetic variation for these specific traits, and the approaches to be utilised.