Natural Variation And Identification Of Microelements Content In Seeds Of Einkorn Wheat (Triticum Monococcum)

Abstract

Micronutrient deficiencies in human beings are common problems, especially in developing world. Among the micronutrient deficiencies, zinc (Zn) and iron (Fe) deficiencies are particularly important affecting severely health of humans. Major reason for the widespread occurrence of micronutrient deficiencies in human beings is the high and monotonous consumption of cereal-based foods with very low content of micronutrients. An increase in concentration of Zn and Fe in grain is, therefore, a high-priority research area. Exploitation of large genetic variation for Zn and Fe existing in cereals germplasm is an important approach to minimize the extent of Zn and Fe deficiencies in developing world. In the present study, the variation for seed content of micronutrients (Zn, Fe, Mn and Cu) in 54 accessions of einkorn wheat (Triticum monococcum) was tested. The accessions have been first grown under same field conditions in 2 locations in Turkey, and the seeds obtained from the field trials were analyzed for micronutrients. In addition, a mapping population with 168 recombinant inbred lines which were grown in 4 locations in Germany, Turkey and Italy has also been tested for the variation of micronutrients in seeds and analyzed for identification of QTLs associated with micronutrient content in seeds The results obtained showed existence of large genotypic variation in content of micronutrients. The contents of Zn and Fe among the 54 einkorn wheat accessions varied from 0.21 to 2.16 μg seed^-1 for Zn with an average of 1.19 μg seed^-1 and from 0.54 to 3.09 μg seed^-1 for Fe with an average of 1.15 μg seed^-1. There was a close positive relationship between seed contents of Fe and Zn. The genetic basis of this variation was elucidated by QTL analysis, using a mapping population comprising 168 recombinant inbred lines that was developed from a cross between 2 cultivated Einkorn genotypes (e.g., ID-362 bread-making quality poor and ID-331 bread-making quality good). From the parents ID-362 had always more Zn than the other parent in all four locations. The four locations presented different mean values, varying from 1.09 to 2.16 μg seed^-1 for Zn content, from 0.83 to 1.97 μg seed^-1 for Fe content, from 1.43 to 1.97 μg/seed^-1 for Mn content and from 0.14 and to 0.24 μg seed^-1 for Cu content. Pooling the results of the four trials, a major QTL, common to all four microelements and explaining from 10 to 30% of the variation (depending on the mineral assayed), was observed only on the chromosome 5, and not on the other chromosomes. The Einkorn germplasm tested had a significant variation for micronutrients, especially Zn and this variation could be exploited inbreeding programs. Chromosome 5 likely carries the genes affecting micronutrient accumulation in Einkorn seeds