Meta-analysis For Grain Zinc And Iron Concentration In Crops And QTL Mapping In Maize

A long-term lack of micronutrient such as zinc and iron in daily diet would bringabout serious health problem. Enhancing the amount of such micronutrients in ediblepart of major crops and then improving the usual intake of the body throughbiofortification is an effective approach to overcome the global hidden hunger.Therefore, breeding new cultivars with enriched micronutrient, especially zinc andiron, would be of great significance.To dissect the genetic basis of grain zinc and iron concentration in crops, thepresent study conducted meta-analysis first for such traits related QTL published inthree staple food crops, that is maize, rice and wheat, to tease the available data andreach the consensus QTL. Comparative mapping of genomes at molecular markerlevel through the method of comparative genomics on the basis of meta-analysis wasperformed then to evaluate the conservation of synteny about grain zinc and ironconcentration in species as well as to deduce the candidate genomic regions or genes.In maize RIL population, QTL mapping for grain zinc and iron concentration wascarried out finally to verify the above supposed genomic regions and to identify newloci. The main results were as follows:1. A total of10mMQTL for maize were found distributed on chromosome2,3,4,5,9and10accounting for8.75%~28.30%of phenotypic variance with the confidenceinterval ranging from9.53cM to212.71cM; and a total of22rMQTL for rice werefound distributed on chromosome1,2,3,4,5,6,7,8,9and12accounting for6.72%~24.30%of phenotypic variance with the confidence interval ranging from7.68cM to20.66cM; and a total of13wMQTL for wheat were found distributed onlinkage group2A,3D,4A,4D,5A,6B and7A accounting for4.56%~40.62%ofphenotypic variance with the confidence interval ranging from1.05cM to46.38cM.Among these, mMQTL2.2and mMQTL2.3for maize, rMQTL1.2, rMQTL6.2andrMQTL8.2for rice, and rMQTL7A.1and rMQTL7A.3for wheat synthesizedmulti-QTL initialed responsible for a high phenotypic variance with a narrowedconfidence interval were likely to candidate MQTL for zinc and iron concentration ingrains.2. Eight of10mMQTL for maize had homologous chromosome regions in riceor wheat genomes containing corresponding MQTL. Among these, mMQTL5/mMQTL9.2for maize, rMQTL7.3for rice and wMQTL2A.2for wheat kept syntenic.3. The gene named Nramp3encoding metal transporter protein in maize located in the homologous MQTL regions about mMQTL9.2for maize and rMQTL3.1for rice may be responsible for the accumulation of zinc and iron in maize grains.4. A total of16and3QTL for grain zinc and iron concentration were detected using498maize RILs at three environments, respectively. There were6stable QTL distributed on chromosome6,7and8, and the QTL mapped on bin6.02linked to marker umc1178explained a relatively higher phenotypic variance,15.86%and9.98%, respectively.5. qZnB2(bin2.08) linked to marker umc1230mapped on chromosome2and qFeX9(bin9.07) linked to marker bnlg1525mapped on chromosome9co-located with mMQTL2.3and mMQTL9.2for maize, respectively, demonstrating that the results of meta-analysis and QTL mapping were consistent.