Genetic variability for the efficiency of nitrogen metabolism among natural and derived Brassica rapa accessions
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
The present situation urgently demands the crop plants with increased nitrogen (N) uptake
and assimilation efficiencies in order to reduce damage caused to the ecosystem due to nitrate
leaching. With this objective, the variation and correlation of N uptake and assimilatory
enzymes with non-enzymatic metabolites and yield parameters was studied at three
developmental stages viz., pre-anthesis, anthesis and post-anthesis in a DArT-genotyped
association panel of 195 Brassica rapa diversity set grown at a recommended dose of 100 kg
N/ha. Among all the growth stages, N-metabolism enzymes were maximally active during
anthesis stage. Correlation study depicted a significant positive relationship between all the
N-metabolism enzymes and biochemical parameters. Out of 195 genotypes, seven promising
genotypes viz., DRBS-56-A5, DRP-31-A5-P5, DRT-80-A5, DRT-59-A1, DRT-66-A2, LTE-
16 and CN107774 recorded highest enzyme activities and nitrogen use efficiency (NUE). Of
these, DRT-59-A1, LTE-16, CN107774 and DRP-31-A5-P5 were higher yielding as well.
The genome wide association study (GWAS) revealed 21 significant SNP’s associated with N
metabolism traits on all the chromosome from A01-A10 except chromosome 4. SNPs that
include A02_1906734 and A03_20450126 individually co-localized with two functional gene
groups that were associated with QTLs for glutamate dehydrogenase, glutamine synthetase
and glutamate synthase. The study helped in identification of genotypes with favorable
combination of traits that could be of interest in Brassica breeding programs. Also, the
identified significant SNPs on further validation could be used for marker assisted selection
and trait introgression in Brassica for raising N uptake and assimilation rates.
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