| Potassium (K) is an essential macroelement for plant growth and development. Many reports showed significant difference in responses to to K deficiency among crops. Screening of K efficient cultivars and sdudy the genetic molecular mechanism of K efficiency would provide materials and gene information for breed high K efficient cultivars with conventional breeding and/or gene engineering, and it will be an economical and sustainable way for the B. napus production.In this study, TN DH population, a double haploid population derived from a cross between NY-7(N) and Tapidor (T), were used to investigate seedling growth, K uptake and accumulation, K utilization efficiency with hydroponics, and seed yield and seed yield components at mature stage with two years field trials at low K and normal K. Genetic analysis for these traits were conducted and quantitative trait loci (QTL) for these traits were mapped on the TN DH map. The main results are as follows:1Effect of K deficiency on the plant growth and seed yield of NY-7and TapidorPlant vegetative and reproductive growth of Tapidor and NY-7were inhibited at K deficiency. The plants showed poor growth vigor and shoot biomass, and K concentration and accumulation at low K of them were lower than those of them at normal K, while the K translocation coefficient (KTC) of them at low K were higher than that of them at normal K. Biomass and grain yield of NY-7were higher than that of Tapidor at low K whether with pot culture or field experiments. Comparing with NY-7, silique number per plant of Tapidor significantly decreased at low K. At the seedling stage, the K utilization efficiency of Tapidor was lower than NY-7.2Phenotypic difference of TN DHpolulation at low and normal KThe significant decline in biomass, K concentration, K accumulation and increased K utilization of TN DH population were observed under low K treatment during hydroponic culture. K insufficient decreased plant height, pod number per plant, seed number per pod and seed yield in two years field experiments. The frequency distributions of all the traits showed continuous phenotypic variation for the TNDH population under different K levels, and significant transgressive segregation was massively observed, suggesting multiple genes involved in action these phenotypic variation. 3QTL detection and analysis for the seedling traits at low and normal KA total of37putative QTLs were identified for dry weight, K concentration, K accumulation, K efficiencies at seedling stage. LOD values of the detected single QTLs ranged from3.3to7.2, and the explained phenotypic variation of these QTL ranged from7.0%to20.5%..Favorable alleles from both NY-7or Tapidor contributed to increase biomass accumulation, and more alleles from Tapidor act on increase effects on traits associated with K uptake, and more alleles from NY-7act on increase K utilization, respectively.4QTL detection and analysis for seed yield and seed yield components at low and high KPlant height (PH), First primary branch height (FPH), Branch number (BN), Pod number per plant (PN), Seed number per pod (SN), Seed weight (1000seed)(SW) and Seed yield (SY) of the TN DH population were investigated at low and high K under field trials. A total of96putative significant QTL for these traits were detected on16of the19chromosomes of Brassica napus, including44and51QTL under normal and low K conditions, respectively. In addition, QTLnetwork2.0, based on a Mixed-Model-based composite interval mapping, was used to detect loci involved in epistatic interactions and Q×E interactions. These pairs of epistatic loci and their different interactions between QTL and non-QTL loci indicated that the K efficiencies for plants were also influenced by the environment factors. |
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