RESUMEN
Nitrogen (N) is a critical input for plant growth and development. A better understanding of N uptake and utilization is important to develop plant breeding strategies for improving nitrogen use efficiency (NUE). With that objective in mind, we assayed a SNP-genotyped association panel comprising 92 inbred lines for the activities of nitrate reductase (NR), nitrite reductase (NIR), glutamine synthetase (GS) and glutamate synthase (GOGAT). All these enzymes are associated with N assimilation. The experiments were carried out at two levels of N application: no added N (N0) and agrnomically recommened dose (100 kg/ha) of N application (N100). Genome wide association studies (GWAS) helped to identify several marker-trait associations (MTAs), involving chromosomes A01, A06, A08, B02, B04, B05 and B08. These explained high phenotypic variation (up to 32%). Annotation of the genomic region(s) in or around significant SNPs allowed prediction of genes encoding high affinity nitrate transporters, glutamine synthetase 1.3, myb-like transcription factor family protein, bidirectional amino acid transporter 1, auxin signaling F-box 3 and oxidoreductases. This is the first attempt to use GWAS for identification of enzyme QTLs to explain variation for nitrogen assimilation enzymes in Brassica juncea.
Asunto(s)
Planta de la Mostaza/enzimología , Planta de la Mostaza/genética , Nitrógeno/metabolismo , Proteínas de Transporte de Anión/genética , Transporte Biológico/genética , Estudio de Asociación del Genoma Completo/métodos , Glutamato Sintasa/genética , Glutamato Sintasa/metabolismo , Glutamato-Amoníaco Ligasa/genética , Glutamato-Amoníaco Ligasa/metabolismo , Nitrato-Reductasa/genética , Nitrato-Reductasa/metabolismo , Transportadores de Nitrato , Nitrito Reductasas/genética , Nitrito Reductasas/metabolismoRESUMEN
A study was conducted under irrigated conditions to test the performance of improved cultivars of Indian mustard (B. juncea), Gobhi sarson (B. napus) and African sarson (B. carinata) under changing climatic conditions. The effect of cultivar, environment and their interactions were significant in mustard and canola gobhi sarson. Environment had significant impact on all the studied traits except for leaf area index (LAI). Cultivar x Year (G x Y) interaction was significant for flowering behavior, days to maturity, SPAD, photosynthetic active radiations (PAR), growth parameters, yield components and yield except photosynthesis photochemical efficiency, relative water content (RWC) and LAI. Cultivar RLC1 surpassed other B. juncea cultivars for yield and had low erucic acid ('0') while GSL1 (non canola), Hyola PAC401 (hybrid canola) and GSC6 (canola) of B. napus were superior in performance for seed yield and possessed low erucic and glucosinolate content ('00'). Higher seed yield was associated with more number of total siliquae/plant, seed weight, biomass, seeds/siliqua, SPAD and RWC. Correlation coefficient revealed high positive association for seed yield with days to maturity (0.639**), plant height (0.982**), secondary branches (0.826**), total siliquae/plant (0.913**), seed weight (0.761**) andbiomass (0.891**).