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Title: Glutamine synthetase in durum wheat: Genotypic variation and relationship with grain protein content

item NIGRO, D - University Of Bari
item FORTUNATE, S - University Of Bari
item GIOVE, S.L. - University Of Bari
item PARADISO, A. - University Of Bari
item Gu, Yong
item BLANCO, A - University Of Bari
item CONCETTA DE PINTO, M - University Of Bari
item GADALETA, A. - University Of Bari

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2016
Publication Date: 7/13/2016
Citation: Nigro, D., Fortunate, S., Giove, S., Paradiso, A., Gu, Y.Q., Blanco, A., Concetta de Pinto, M., Gadaleta, A. 2016. Glutamine synthetase in durum wheat: genotypic variation and relationship with grain protein content. Frontiers in Plant Science. doi: 10.3389lfpls.2016.00971.

Interpretive Summary: Agricultural production has increased in recent decades through the diffusion of modern crop production practices, such as the spread of high-yielding crop varieties and a heavier use of mineral fertilizers. Nitrogen (N) is the most important nutrient for plant growth. In the last 40 years, the amount of nitrogen fertilizers supplied to crops has risen dramatically from 12 to 104 teragrams per year. This excess in synthetic N supply significantly increased yields, but also negatively impacted the environment. One of the most valuable agronomic and physiological indicators of how plants respond and use available N is Nitrogen Use Efficiency (NUE). Glutamine synthase (GS), an enzyme with an essential role in the assimilation of inorganic N, has been proposed as a key candidate for improving NUE. In this study, the total GS expression and activity were examined in relation to grain protein concentration (GPC) in 10 different wheat genotypes. The results show that N treatment doesn’t affect GS expression and activity or the final GPC. The GS activity is genotype-dependent. Therefore, breeding cultivars with high NUE is important for efficient N management and for sustainability of agricultural production.

Technical Abstract: Nitrogen Use Efficiency (NUE), one of the most valuable indicators for nitrogen use in crops, both in terms of yield and final grain protein content (GPC), is a very complex trait. The identification of wheat varieties with high NUE, as well as the characterization of central enzymes involved in these processes, is important for more sustainable agricultural practices. In this study we focused on Glutamine synthetase (GS) as a candidate to study NUE and GPC in wheat. We analyzed GS expression and its enzymatic activity in different tissues and phenological stages in ten durum wheat genotypes with different GPC. Although each genotype performed quite differently from the others, both because of their genetic variability and their adaptabilities to specific environmental conditions, an higher average activity and expression were found in genotypes with higher GPC compared to low GPC ones. Moreover, GS behaved differently in roots and leaves of genotypes with contrasting GPC growth at different nitrogen regimes. High nitrogenous supplement increased GS expression and activity in roots in all genotypes, highlighting the key role of GS in root nitrogen assimilation and ammonium detoxification. Otherwise, the nitrogenous treatments did not affect GS expression and activity in leaves, nor the final GPC in all analyzed genotypes. These data highlighted that GS activity is a genotype-dependent parameter, the enzyme playing an important role in NUE processes. Breeding cultivars with high NUE is of primary importance for more efficient nitrogen management and for sustainability of agricultural production.