QTL Identification And Mapping Of Grain Cadmium Accumulation Based On Segment Substitution Lines Of 9311 In Rice(Oryza Sativa L.)

Soil pollution caused by heavy metal pollution is a hot spot and a major problem for food safety and soil remediation because of its heavy pollution,wide area,and difficult governance.Among them,heavy metal cadmium(Cd)pollution is the most prominent.Rice is one of the most important food crops in the world.The content of heavy metals in rice is an important indicator that affects the quality and safety of rice.Cd as a toxic heavy metal element seriously affects food safety.In order to analyze the genetic mechanism of Cd transport and accumulation in rice,a low-Cd rice cultivar was selected.In this study,the Indica rice 9311,japonica rice variety Nip,and9311 as recurrent parents,and Nip as donor parents constructed chromosome segment substitution lines(CSSLs)were selected.137 populations were used as research subjects,9311 and Nip for indoor hydroponic experiments.Indica rice 9311 of different growth stages and tissues were used.9311,Nip,and chromosome segment substitution lines were planted in the Cd polluted field in Mianzhu.Grains of mature materials were collected.Determination of Cadmium Content in Water Cultured Samples and Brown Rice by Inductively Coupled Plasma Mass Spectrometry to Analyze the Differences in Cadmium Content between Parents,Combining Cadmium Content in Brown Rice and the Method of Reducing Representation Genome Sequencing(RRGS)The QTLs for reducing rice Cd content in segment substitution populations were initially located.Get the following result:1.The parental 9311 and Nip were treated with a 1 ?M cadmium solution,and the Cd content of samples from 9311 and Nip was determined.It was found that the seedling stage underground 9311 was significantly higher than Nip,the aerial part 9311 was slightly lower than Nip,the transfer coefficient(S/R)9311 was 0.38,and Nip was 0.71,9311 <Nip;9311 and Nip were in the flood season to grain filling stage The Cd content continued to increase,and 9311 was consistently significantly higher than Nip.It reached a peak at the grain-filling stage,accounting for 22.7 mg/kg at 9311,19.01 mg/kg at Nip,in mature period 9311 fall 18.90% 9,and Nip fall 0.79%,in the glume 9311 Higher,Nip grows faster.This indicates that Nip's ability to transport Cd is stronger than that of 9311,but more Cd is retransported in the leaves of 9311 during the mature period,which may be one of the reasons for the difference in Cd content between the two rice varieties.2.In the parental and chromosomal segment substitution populations planted in the Mianzhu Experimental Field,Nip brown rice has the lowest Cd content.The Cd content of brown rice was relatively low in the two-year substitution population(r=-0.33).By comparing the differences(?)in the relative values of Cd content in the brown rice of the population,25 brown rice Cd contents were found to be stable(?<0.01)of the lines,of which CSSLs2-7 brown rice had the lowest Cd content,0.84 mg/kg in 2016 and 0.57 mg/kg in 2017.3.Six QTLs with reduced Cd content in rice were found on chromosomes 4,6,and 8 using the method of fragment overlap and Reducing Representation Genome Sequencing.The qCd-6-2 localization interval contained qCd-6-1 and OsHMA2,qCd-8-1 was detected in 2 years.It was speculated that qCd-6-2 and qCd-8-1 may have major QTLs that reduce Cd content in rice.