Abstract
Previous studies showed that wide genotype differences in nitrogen (N) efficiency exists among cultivars of rapeseed (Brassica napus L.), but the mechanisms behind those differences are still unknown. In the present study, our aim was to analyze the adaptability mechanism of N-efficient rapeseed to low-N stress by employing two genotypes of natural variation in N efficiency. Nitrogen-efficient genotype, ‘BG51’, and N-inefficient genotype, ‘BG88’, were grown in a solution culture experiment under conditions of high-N (6.0 mM N) and low-N (0.6 mM N) supply. After growing 30 d, roots and shoots were sampled for the analysis of dry weight, N concentration and accumulation, N use efficiency (NUE), N transport efficiency (NTE), root system vigor parameters, nitrate redutase (NR) activity, and glutamine synthetase (GS) activity. Nitrogen deficiency decreased shoot and root dry weight significantly, but ‘BG51’ exhibited a significantly lower decrease in shoot dry weight and had significantly higher biomass production than ‘BG88’. Under low N supply ‘BG51’ accumulated more N in shoot, root and whole plant than ‘BG88’, and presented higher NUE in both shoot and root. Low-N stress induced an increase in maximum root length by 28.3% for ‘BG88’ and 55.1% for ‘BG51’ compared with the high-N treatment. And ‘BG51’ presented larger root volume, higher root vigor, larger root total absorbing area and root active absorbing area than ‘BG88’ in low-N treatment. Furthermore, ‘BG51’ had significantly higher NR and GS activity in both leaf and root in low N treatment than ‘BG88’, while there was no evident difference between them in high N treatment. These results suggested that N-efficient rapeseed germplasm of natural variation involves an integrated adaptability mechanism responding to low-N stress. Namely, N-efficient genotype could form more developed root system to accumulate more N, and presented efficient N assimilation by higher NR activity and GS activity than N-inefficient genotype. These ultimately resulted in high tolerance of N-efficient genotype to low-N stress and high biomass production.
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Claims 12
Claim · model-written summary
Nitrogen deficiency significantly decreased rapeseed shoot and root dry weight.
Not reportedComparator
Verbatim
e0“Nitrogen deficiency decreased shoot and root dry weight significantly”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 had a significantly smaller shoot dry weight decrease and greater biomass than BG88.
Verbatim
e0“‘BG51’ exhibited a significantly lower decrease in shoot dry weight and had significantly higher biomass production than ‘BG88’”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 produced significantly more biomass than BG88.
Verbatim
e0“‘BG51’ exhibited a significantly lower decrease in shoot dry weight and had significantly higher biomass production than ‘BG88’”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
Under low nitrogen, BG51 accumulated more nitrogen in shoot, root and whole plant than BG88.
Verbatim
e0“Under low N supply ‘BG51’ accumulated more N in shoot, root and whole plant than ‘BG88’”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
Under low nitrogen, BG51 had higher nitrogen use efficiency in shoots and roots than BG88.
Verbatim
e0“presented higher NUE in both shoot and root”
e1“Under low N supply ‘BG51’ accumulated more N in shoot, root and whole plant than ‘BG88’”
e2“rapeseed (Brassica napus L.)”
Claim · model-written summary
Low nitrogen increased maximum root length of BG88 by 28.3% relative to high nitrogen.
Verbatim
e0“Low-N stress induced an increase in maximum root length by 28.3% for ‘BG88’ and 55.1% for ‘BG51’ compared with the high-N treatment”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
Low nitrogen increased maximum root length of BG51 by 55.1% relative to high nitrogen.
Verbatim
e0“Low-N stress induced an increase in maximum root length by 28.3% for ‘BG88’ and 55.1% for ‘BG51’ compared with the high-N treatment”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 had larger root volume and higher root vigor than BG88 under low nitrogen.
Verbatim
e0“‘BG51’ presented larger root volume, higher root vigor, larger root total absorbing area and root active absorbing area than ‘BG88’ in low-N treatment”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 had larger root total and active absorbing areas than BG88 under low nitrogen.
Verbatim
e0“‘BG51’ presented larger root volume, higher root vigor, larger root total absorbing area and root active absorbing area than ‘BG88’ in low-N treatment”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 had significantly higher leaf and root NR activity than BG88 under low nitrogen.
Verbatim
e0“‘BG51’ had significantly higher NR and GS activity in both leaf and root in low N treatment than ‘BG88’”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
BG51 had significantly higher leaf and root GS activity than BG88 under low nitrogen.
Verbatim
e0“‘BG51’ had significantly higher NR and GS activity in both leaf and root in low N treatment than ‘BG88’”
e1“rapeseed (Brassica napus L.)”
Claim · model-written summary
NR and GS activity showed no evident genotype difference at high nitrogen.
Verbatim
e0“while there was no evident difference between them in high N treatment”
e1“‘BG51’ had significantly higher NR and GS activity in both leaf and root in low N treatment than ‘BG88’”
e2“rapeseed (Brassica napus L.)”
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nitrogen · growth · Brassica napus (oilseed rape)Positive and negative results
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- positive
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