Meta-analysis of QTLome for grain zinc and iron contents in wheat (Triticum aestivum L.)

Zinc and iron are essential micronutrients for the growth, development, and maintenance of the immune system at high levels. Analysis of genetic control of grain Zn and Fe through identification of QTLs helps to identify linked markers for use in marker- assisted breeding and biofortification of wheat grain in breeding programs. Meta-QTL analysis (MQTL analysis) is a robust method to integrate information on QTLs in independent populations, which is useful for understanding the genetic architecture of quantitative traits. In this meta-analysis, information on QTLs for iron and zinc contents in seven independent segregating populations was used to develop a reference consensus map. The consensus map consisting of 558 DNA markers covered 1028 cM of the wheat genome and seven MQTLs were identified on six wheat chromosomes. The MQTLs identified possessed a narrower (7.03 cM) confidence interval (CI) than the original QTLs with a mean CI of 17.60 cM. Of the MQTLs identified, three MQTLs covering at least four initial QTLs from independent studies were the most important hot spots for the genetic control of grain Zn and Fe traits over different genetic backgrounds and environments. The identified MQTLs were predominantly distributed in the non-telomeric and sub-telomeric chromosomal regions. Functional analysis of the identified MQTLs suggested that the genomic regions of the most identified MQTLs were associated with the position of candidate genes (CGs) for Zn and Fe homeostasis. Overall, the results of the meta-analysis showed that QTLs for Zn and Fe contents were highly co-located (57.1%), suggesting the simultaneous improvement of both micronutrients and biofortification of wheat.