| Rice is one of the most important food crops in the world,China is also the largest consumer of rice.However,due to increased emissions of industrial wastes,sewage irrigation,atmospheric subsidence and heavy use of phosphorus fertilizers,the paddy field is severely polluted by heavy metals.Among them,cadmium pollution is the most serious.Cadmium is unnecessary elements in our body and is one of the most toxic heavy metal elements,and rice has a strong ability to absorb cadmium,so in recent years there have been media exposure "cadmium rice" event,it poses a serious threat to human health.Therefore,the study of cadmium accumulation and QTL mapping in rice has important guiding significance for the cultivation of low cadmium varieties in rice.Single segment substitution line(SSSL)eliminates the interference of the genetic background and is an important material for the localization and aggregation of Quantitative Trait Loci(QTL).In this study,the identification of cadmium accumulation QTL was carried out by using 21 SSSL with low cadmium content.Simultaneously,molecular marker detection was conducted for 37 samples of polymeric materials with different grain cadmium accumulation QTL in the late season of 2015,to select the homozygous material and to detect the cadmium content in grain,analyzing the aggregation effect of cadmium accumulation QTL in grain.In this paper,the cadmium content of grain was tested in homozygous plant,and the aggregation effect of cadmium accumulation QTL was analyzed.In addition,the main agronomic characters of 21 single segment substitution line and 37 homozygous polymer materials were investigated in the late season of 2017.The main results are as follows:1、In the early and late season of 2016 and 2017,the content of cadmium in grain in single segment substitution substitution was tested.The results showed that there was obvious variation in phenotype of different genotypes of rice,and is vulnerable to environmental factors,but overall grain cadmium content is shown as: shaoguan heavymetal pollution field > the school teaching experimental base.2 、 In this study,11 QTLs that control the accumulation of cadmium in grain were detected,and they were located on chromosome 1,2,3,4,5,6,7,8 and 11.10 QTLs with low cadmium accumulation,respectively qCd-1-1,qCd-2-1,qCd-3-1,qCd-3-2,qCd-4-1,qCd-5-1,qCd-6-1,qCd-8-1,qCd-8-2 and qCd-11-1.Another QTL qCd-7-1 shows the opposite effect due to different donor sources,and may be different alleles of the same QTL.3、From the early season in 2016 to the late season in 2017,a total of four seasons in two years,the molecular marker detection of 37 polymer materials was conducted to select the homozygote,planting in shaoguan pollution field and the experimental field of our school,testing the cadmium content of grains,analyzing different aggregation effect of QTL of cadmium accumulation in grain.Study found that with the increase of polymerization on the number of QTL,cadmium content in rice grain showed a trend of decrease of the overall,moreover,the content of cadmium in the grain of the heavy metal pollution field in shaoguan has a large decreasing than that in our school experimental base,the aggregation effect is more apparent.Through the analysis of the polymerization effect,the real existence of these microeffect QTLs was further confirmed,and the low cadmium QTL could be detected more easily under high cadmium conditions.These excellent single-segment substitution and polymeric materials provide a theoretical basis for the identification and aggregation breeding of cadmium accumulation QTL in rice.4、The main agronomic characters of 21 SSSL and 37 homozygous polymer materials were investigated in the late season of 2017.The results indicated that the cadmium content of rice was low,which could be affected by the short heading stage,and provide guidance for the cultivation of low cadmium accumulation cultivars in rice.Based on the identification of cadmium accumulation QTL of rice grain,this study polymerized Cd low accumulation QTL.The results indicate that these micro-effects QTL are real,and the new varieties of rice with lower cadmium content can be obtained by polymerization.It provides a theoretical basis for the low accumulation of gene polymerization in rice.At the same time,the relationship between cadmium accumulationand heading stage was studied in this experiment,which also provided a reference for the selection and breeding of low accumulation of cadmium in rice. |
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