| According to the World Health Organization(WHO),selenium is one of the 14 trace elements necessary for the human body.Selenium has the functions of detoxification,detoxification,anti-oxidation,strengthening human immunity,anti-cancer and anti-aging in the organism.The Chinese Nutrition Society recommends that adults must supplement 50-250 micrograms of selenium per person per day,which can directly and effectively prevent more than40 diseases including diabetes,cancer and cardiovascular diseases,and indirectly participate in the prevention of more than 400 diseases.Foxtail millet has the characteristics of small genome,wide adaptability,tolerance to barrenness,and rich in various nutrients.It is the first of miscellaneous grains and one of the ideal materials for selenium-rich crops.The selenium content in ordinary foxtail millet is quite different,and the highest total selenium content in the grain is only 44.90μg·kg-1.Therefore,the reasonable application of selenium fertilizer to produce selenium-enriched foxtail millet is one of the important ways to improve the efficiency of foxtail millet planting.This study screened and evaluated the selenium responsiveness of 224 foxtail millet core germplasm resources,and explored the comprehensive mechanism regulating the selenium responsiveness of fontail millet from the phenotype,physiology and candidate genes.The main results are as follows:1.In this study,224 core germplasm resource materials of foxtail millet with basically the same growth period were selected and planted in the molecular breeding base of coarse grains of Shanxi Agricultural University.The leaves of millet were sprayed with 67.84 g·hm-2 at the heading stage and the filling stage.Selenium fertilizer(sodium selenite),use the measured data to analyze the correlation between the indicators,use the membership function method to comprehensively evaluate the measured indicators,and finally use the selenium effect comprehensive index D value clustering to divide 224 materials There are seven grades,of which category I is selenium-efficient varieties with the strongest selenium response capacity,a total of 9copies,and category VII is selenium-inefficient varieties with the weakest selenium response capacity,totaling 32 copies.2.Through preliminary screening and evaluation,50 foxtail millet resources with different selenium effects were selected as materials according to the comprehensive evaluation value(D Value),and their agronomic characteristics,yield,and grain selenium content were further analyzed.The results showed that: 1)the leaf length,leaf width and ear length of some varieties with strong and weak selenium effect changed after applying selenium on the leaf surface;2)the foxtail millet material with strong selenium effect was better than the foxtail millet material with weak selenium effect The yield has increased greatly,with an average increase of 2.97%;3)The total selenium content of the grains of materials with strong selenium effect is higher than that of materials with low selenium efficiency.The average content of the former is 0.279 mg·kg-1,while the latter is only 0.19 mg·kg-1.It further shows that the selenium accumulation water of the cultivars with strong selenium effect is higher than that of the materials with weak selenium effect.3.Analyze the agronomic characteristics(plant height,stem thickness,leaf length,leaf width and leaf number)of 224 millets at heading stage,agronomic characteristics(plant height,stem thickness,leaf length and leaf width)and selenium effect coefficient during grain filling stage Both agronomic traits and selenium effect coefficients showed a wide range of variation,and showed a normal distribution,indicating that these traits are controlled by multiple genes and belong to the inheritance of quantitative traits,which are suitable for GWAS(Genome wide association study)analysis.The 1,410,570 SNP markers covering the whole millet genome were analyzed for association with phenotypic traits,and it was found that at a significant level of P<0.000001,the above traits were associated with 104 significant SNP marker sites.4.The significant SNP marker sites associated with the whole genome are analyzed by the candidate gene prediction software IGV and located on the "Xiao mi" foxtail millet reference genome constructed in the early stage of our laboratory,and the region of 50 kb above and below the extremely significant associated sites Candidate gene prediction is carried out in the internal,and a total of 110 candidate genes have been screened.Among them,there are 75 genes with known functions and 35 genes with unknown functions.The functional annotations involve nitrate transporter,RNA polymerase,ethylene response transcription factor,and hydroxyl.Pyruvate reductase,non-characteristic mitochondrial proteins,monodehydroascorbate reductase,glycoproteins,leucine protein kinases,etc.are related to the functions of selenium metabolism and biosynthetic pathways related to the antioxidant capacity of plants and the hormone regulation system,Sulfur assimilation metabolic pathways,etc.5.Haplotype analysis of genes related to selenium metabolism: According to the annotation of genome-wide association analysis of gene function,the candidate gene association analysis of the two candidate genes Si6g04600 and Si3g15130 was used to establish the relationship between the phenotype and genotype of the trait,and it was found after analysis Some germplasms have one or more haplotypes on Si6g04600 and Si3g15130,and there are both synonymous and nonsynonymous mutations(Synonymous)and nonsynonymous(Nonsynonymous)phenomena.The subsequent identification of favorable haplotypes related to the selenium effect Exploiting high-efficiency selenium materials to provide the molecular basis and germplasm resources for the study of selenium enrichment in foxtail millet is of great significance for in-depth analysis of the molecular response mechanism of selenium sprayed on the leaves of foxtail millet. |
PDF Full Text Request