Challenges to develop nitrogen-fixing cereals by direct nif-gene transfer

CURATTI L; RUBIO LM

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2014

0168-9452

Some regions of the developing world suffer low cereal production yields due to low fertilizer inputs,among other factors. Biological N2fixation, catalyzed by the prokaryotic enzyme nitrogenase, is an alter-native to the use of synthetic N fertilizers. The molybdenum nitrogenase is an O2-labile metalloenzymecomposed of the NifDK and NifH proteins, which biosyntheses require a number of nif gene products. Achallenging strategy to increase cereal crop productivity in a scenario of low N fertilization is the directtransfer of nif genes into cereals. The sensitivity of nitrogenase to O2and the apparent complexity ofnitrogenase biosynthesis are the main barriers identified so far. Expression of active NifH requires theproducts of nifM, nifH, and possibly nifU and nifS, whereas active NifDK requires the products of nifH,nifD, nifK, nifB, nifE, nifN, and possibly nifU, nifS, nifQ, nifV, nafY, nifW and nifZ. Plastids and mitochondriaare potential subcellular locations for nitrogenase. Both could provide the ATP and electrons requiredfor nitrogenase to function but they differ in their internal O2levels and their ability to incorporateammonium into amino acids.