| Wild rice has been subjected to natural environment selection of the long-term evolution process,which has some high-quality genes that are not cultivated in rice.Breeders have excavated many excellent traits and genes from wild rice,such as cold tolerance,disease resistance,and high yield.In recent years,Cd pollution of cultivated land in southern China has become increasingly serious,and rice has a strong cadmium enrichment characteristic,resulting in serious exceeding of Cd content of rice grains,which further affect the quality of rice.It is significantly important for rice variety improvement that excavating and utilizing cadmium uptake genes of wild rice and mapping their QTLs.In this study,Chaling wild rice(Oryza rufipogon Griff.)was used as donor parent and indica rice 9311 as the recurrent parent.High-generation backcrossing substitution lines obtained by hybridization and backcrossing were used as materials.Using cadmium content in brown rice as an evaluation index,and then to the identification of cadmium content in brown rice.61 cadmium low-absorption and 20 cadmium-high-absorption lines were selected from1045 substitution lines to form extreme phenotypic lines.The extreme phenotypic lines were analyzed by 1124 SNP microarray markers for rice genome,and affecting the QTL which affecting cadmium absorption.The main results are as follows:(1)The cadmium content of brown rice of 1045 substitution lines was0.193-3.440 mg/kg.The cadmium content of brown rice of recipient parent 9311 was1.77±0.21 mg/kg.(2)According to the identification results of cadmium accumulation in brown rice in 2017,61 extreme cadmium low absorption and 20 extreme cadmium high absorption lines were selected from the substitution line.All of those brown rice of 81 extreme phenotypic lines which reappraisal the cadmium content in 2018.There were significant or extremely significant differences in phenotype between 46 lines and recipient parents 9311 in 61 extreme cadmium low absorption lines,3 strains and recipient parents 9311 in 20 extreme cadmium high absorption strains in two-year identification test.(3)Correlation analysis of Cd content and SNP loci in brown rice of extreme phenotypic lines,combined with graphic genotype method and QTL Naming Method.In 2017,a low cadmium uptake QTL(qCd1-1)was located on chromosome 1,and its size was 895.1kb.The contribution rate was 24.48%,a low cadmium uptake QTL(qCd7-1)was located on chromosome 7,with a size of 528.1 kb and a contribution rate of 32.14%.Only one low cadmium uptake QTL was detected on chromosome 7in 2018.Compared with qCd7-1 detected on chromosome 7 in 2007,the contribution rate of qCd7-1 was 24.76%.Both 2017 and 2018 were detected as a stable QTL.This study provides a basis of making full use of the wild rice resources of Chaling and cultivating low cadmium uptake varieties. |
