Engineering nitrogen use efficient crop plants: the current status

Abstract

SummaryIn the last 40 years the amount of synthetic nitrogen (N) applied to crops has risen drastically, resulting in significant increases in yield but with considerable impacts on the environment. A requirement for crops that require decreased N fertilizer levels has been recognized in the call for a 'Second Green Revolution' and research in the field of nitrogen use efficiency (NUE) has continued to grow. This has prompted a search to identify genes that improve the NUE of crop plants, with candidate NUE genes existing in pathways relating to N uptake, assimilation, amino acid biosynthesis, C ⁄ N storage and metabolism, signalling and regulation of N metabolism and translocation, remobilization and senescence. Herein is a review of the approaches taken to determine possible NUE candidate genes, an overview of experimental study of these genes as effectors of NUE in both cereal and non-cereal plants and the processes of commercialization of enhanced NUE crop plants. Patents issued regarding increased NUE in plants as well as gene pyramiding studies are also discussed as well as future directions of NUE research.

The contents of free amino acids and elements in As-hyperaccumulator Pteris cretica and non-hyperaccumulator Pteris straminea during reversible senescence

“…In the PS fern, the major AAs accumulated in the fronds were Gly after 35 days and Asn, Gln and Glu after 83 days. Asparagine, Gln, Glu and Asp have N remobilization/transport/storage function in senescing leaf cell (McAllister et al 2012). According to Figure 2, AAs were not accumulated after 160 days.…”

Agribiotechnology: Blue-sky rice

“…The International C 4 Rice Consortium (ICRC), headquartered at the International Rice Research Institute (IRRI) in Los Baños, the Philippines, estimates that the supercharged rice could support yield increases of a remarkable 30-50% with the same amount of water and fertilizer used on current C 3 crops.…”

“…While investigating stresses from drought and shortfalls of oxygen, the team discovered that crop plants that over-produce alanine aminotransferase (AlaAT), an enzyme that catalyses the transformation of amino acids, have enhanced nitrogen uptake. The researchers showed 4 that if they insert a barley AlaAT gene, and a promoter -a molecular on-off switch -into canola, the plants use nitrogen more efficiently than control plants. The team has expanded its canola work, inserting AlaAT into rice and other cereal crops.…”

Nitrato modula os teores de cloreto e compostos nitrogenados em plantas de milho submetidas à salinidade

“…Entre os principais elementos essenciais destaca-se o nitrogênio (N), que é constituinte de muitas biomolécu-las, tais como proteínas, ácidos nucleicos e aminoácidos (McAllister et al, 2012), sendo, portanto, requerido em altas concentrações pelas plantas. A deficiência de N inibe rapidamente o crescimento e, consequentemente, a produção vegetal (Williams e Miller, 2001;McAllister et al, 2012).…”

“…A deficiência de N inibe rapidamente o crescimento e, consequentemente, a produção vegetal (Williams e Miller, 2001;McAllister et al, 2012). O N está disponível às plantas principalmente como uma mistura de NH 4 + e NO 3 -, sendo esse último íon a forma predominante (Miller et al, 2007).…”