RESUMO
Genetic improvement is the fundamental basis for improving nitrogen-use efficiency. A better understanding of genetic factors controlling nitrogen uptake and utilization is required for crop genetic improvement. In this study, we identified the quantitative trait loci (QTLs) associated with traits of nitrogen uptake and utilization by using the single-sequence repeat marker method and a recombinant inbred line (RIL) population derived from a super hybrid Xieyou9308. All the traits investigated were inherited quantitatively by continuous variation and showed normal distribution in phenotype with transgressive segregation in the RIL population. Most of the traits were significantly correlated with each other except for nitrogen absorption ability (NAA) with nitrogen harvest index (NHI) and NHI with agricultural nitrogen-absorption efficiency (ANAE). At logarithmic odds value of 2.3, total 13 candidate QTLs, including 4 for NAA, 2 for NHI, 2 for physiological nitrogen-use efficiency, 1 for agricultural nitrogen-use efficiency (ANUE), and 4 for ANAE, were detected and mapped on chromosomes 2, 3, 4, 5, 8, 9, 10, and 12. Significant pleiotropic effect or neighboring expression of QTLs was observed among traits. At position 64.8 cM on chromosome 4 near the marker RM5757, there was a QTL cluster of NAA, ANUE, and ANAE, and at chromosome 5 near the marker RM5968, there was a QTL cluster of NAA and ANUE. The QTL clusters might provide partial explanation and genetic mechanism for the observed correlations between nitrogen uptake and utilization efficiency traits and might form a basis for future breeding programs.
Assuntos
Quimera/genética , Fertilizantes/análise , Nitrogênio/metabolismo , Oryza/genética , Locos de Características Quantitativas , Transporte Biológico , Quimera/metabolismo , Mapeamento Cromossômico , Cromossomos de Plantas/química , Ligação Genética , Marcadores Genéticos , Pleiotropia Genética , Genótipo , Repetições de Microssatélites , Família Multigênica , Oryza/metabolismo , Fenótipo , Plantas Geneticamente ModificadasRESUMO
Elymus sibiricus L. is an important forage grass widely distributed in Asia and is usually a dominant species on Tibetan Plateau alpine grasslands. Here, we used the seed development indices of 1000 seed weight, seed moisture content, and seed viability to compare the seed characteristics at 10, 20, 30, 40, 50, and 60 days after anthesis (DAA) in five populations of E. sibiricus growing in Gannan, China. Additionally, seeds collected at 60 DAA were air-dried for one month, and the primary germination percentage (GP) was determined in the laboratory. Treatment of seeds with 0.2% KNO3, 100 mg/L cytokinin, and 500 mg/L GA3 were tested for their effects on dormancy. A primary GP of 16% was found after 12 d of 15/25°C incubation, with no differences among the five populations. The 1000 seed weight and seed viability steadily increased and moisture content continuously fell with DAA. The optimal harvest time for E. sibiricus in an alpine pasture was 50 DAA. No effect on dormancy was found after treating seeds with 0.2% KNO3 or 100 mg/L cytokinin; however, a low concentration of GA3 induced a prompt and synchronized germination. Freshly matured E. sibiricus seeds were classified to be in non-deep physiologically dormant. Treatment of seeds with GA3 before sowing enhanced the emergence speed and seedling uniformity in E. sibiricus.