Abstract
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.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 10
Claim · model-written summary
Physiological traits varied significantly among maize genotypes.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A significant genotypic variation was found for these traits”
e1“nitrate content, nitrate reductase (NR), and glutamine synthetase (GS) activities”
e2“maize (Zea mays)”
e3“recombinant inbred lines of maize”
Claim · model-written summary
Leaf nitrate content correlated positively with yield and its components.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a positive correlation was observed between nitrate content, GS activity and yield, and its components”
e1“maize (Zea mays)”
Claim · model-written summary
Glutamine synthetase activity correlated positively with yield and its components.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a positive correlation was observed between nitrate content, GS activity and yield, and its components”
e1“maize (Zea mays)”
Claim · model-written summary
Nitrate reductase activity correlated negatively with yield.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NR activity, on the other hand, was negatively correlated.”
e1“yield, and its components”
e2“maize (Zea mays)”
Claim · model-written summary
The authors attribute increased maize productivity to leaf nitrate accumulation and remobilization.
- Compound
- nitratee0
- Outcome
- increased productivitye0
- Qualifier
- efficiently remobilize this stored nitrogen during grain fillinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
Claim · model-written summary
QTL for agronomic and physiological traits were mapped in maize.
- Outcome
- Quantitative trait loci (QTL) for various agronomic and physiological traitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Quantitative trait loci (QTL) for various agronomic and physiological traits were searched for and located on the genetic map of maize.”
Claim · model-written summary
Yield QTL coincided with cytosolic GS genes and enzyme activity.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Coincidences of QTL for yield and its components with genes encoding cytosolic GS and the corresponding enzyme activity were detected.”
e1“maize (Zea mays)”
Claim · model-written summary
The chromosome 5 GS locus was proposed as a partial explanation for variation in yield or kernel weight.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the GS locus on chromosome 5 is a good candidate gene that can, at least partially, explain variations in yield or kernel weight”
e1“maize (Zea mays)”
Claim · model-written summary
QTL for grain yield, GS activity, NR activity and nitrate content coincided at the locus.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at this locus coincidences of QTLs for grain yield, GS, NR activity, and nitrate content were also observed”
e1“maize (Zea mays)”
Claim · model-written summary
The authors hypothesize that nitrate accumulation and NR and GS reactions are coregulated and control nitrogen use efficiency.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”