To enhance our understanding of the genetic basis of nitrogen use efficiency in maize (Zea mays), we have developed a quantitative genetic approach by associating metabolic functions and agronomic traits to DNA markers. In this study, leaves of vegetative recombinant inbred lines of maize, already assessed for their agronomic performance, were analyzed for physiological traits such as nitrate content, nitrate reductase (NR), and glutamine synthetase (GS) activities. A significant genotypic variation was found for these traits and a positive correlation was observed between nitrate content, GS activity and yield, and its components. NR activity, on the other hand, was negatively correlated. These results suggest that increased productivity in maize genotypes was due to their ability to accumulate nitrate in their leaves during vegetative growth and to efficiently remobilize this stored nitrogen during grain filling. Quantitative trait loci (QTL) for various agronomic and physiological traits were searched for and located on the genetic map of maize. Coincidences of QTL for yield and its components with genes encoding cytosolic GS and the corresponding enzyme activity were detected. In particular, it appears that the GS locus on chromosome 5 is a good candidate gene that can, at least partially, explain variations in yield or kernel weight. Because at this locus coincidences of QTLs for grain yield, GS, NR activity, and nitrate content were also observed, we hypothesize that leaf nitrate accumulation and the reactions catalyzed by NR and GS are coregulated and represent key elements controlling nitrogen use efficiency in maize.

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Fusarium head blight (FHB), primarily caused by Fusarium graminearum in North America can result in significant losses in the yield and quality of wheat (Triticum aestivum L). Resistance sources have been largely limited to Chinese germplasm and, in particular, Sumai 3 or its derivatives. In recent years, resistance has been identified in Europe. Previous studies using the wheat line ‘Bizel’, developed in France, have shown that it has resistance to Fusarium head blight. Pedigree information shows that one of its progenitors is rye. This experiment was conducted to determine if ‘Bizel’ has rye chromatin, with the goal of developing a strategy for mapping FHB resistance genes. Two methods based on repetitive DNA sequences specific to rye were implemented. With both approaches, it was demonstrated that ‘Bizel’ does not contain rye chromatin. Consequently, wheat SSRs can be used to map ‘Bizel’ resistance genes for FHB.

Short Stature Maize (SSM), which carries the brachytic2 (br2) mutation has reduced plant height and increased plant standability. Since a large area of maize (Zea mays L.) is planted for silage, it is important to investigate the forage nutritive value of SSM. Our aim was to evaluate the effect of the br2 mutation alone or its combination with the brown midrib3 (bm3) mutation on feeding value parameters, notably fiber digestibility and lignification. SSM hybrids had forage feeding value equivalent to BMR hybrids and better than that of tall hybrids. The br2 mutation significantly increased fiber digestibility in the sets of near‐isogenic inbreds by 4 percentage units and hybrids by 2.7 percentage units. Those favorable effects could be attributed to reduction in lignin concentration and changes in the distribution of lignin within the stem. Furthermore, the combination of br2 with bm3 resulted in an increase of fiber digestibility, which appeared to be additive. Altogether, our results indicated that SSM has the potential to create fodder of high feeding value and favorable standability.This article is protected by copyright. All rights reserved