Detection of quantitative trait loci controlling grain zinc concentration using Australian wild rice, Oryza meridionalis, a potential genetic resource for biofortification of rice.

Ryo Ishikawa,Naoya Miyazaki,Yuki Tsujimura,Shusaku Yoshida,Kenta Taniko,Chhourn Orn,Gotaro Monden,Jian Feng Ma,Takashige Ishii,Masahide Iwata

doi:10.1371/journal.pone.0187224

Abstract

Zinc (Zn) is one of the essential mineral elements for both plants and humans. Zn deficiency in human is one of the major causes of hidden hunger, a serious health problem observed in many developing countries. Therefore, increasing Zn concentration in edible part is an important issue for improving human Zn nutrition. Here, we found that an Australian wild rice O. meridionalis showed higher grain Zn concentrations compared with cultivated and other wild rice species. The quantitative trait loci (QTL) analysis was then performed to identify the genomic regions controlling grain Zn levels using backcross recombinant inbred lines derived from O. sativa ‘Nipponbare’ and O. meridionalis W1627. Four QTLs responsible for high grain Zn were detected on chromosomes 2, 9, and 10. The QTL on the chromosome 9 (named qGZn9), which showed the largest effect on grain Zn concentration was confirmed with the introgression line, which had a W1627 chromosomal segment covering the qGZn9 region in the genetic background of O. sativa ‘Nipponbare’. Fine mapping of this QTL resulted in identification of two tightly linked loci, qGZn9a and qGZn9b. The candidate regions of qGZn9a and qGZn9b were estimated to be 190 and 950 kb, respectively. Furthermore, we also found that plants having a wild chromosomal segment covering qGZn9a, but not qGZn9b, is associated with fertility reduction. qGZn9b, therefore, provides a valuable allele for breeding rice with high Zn in the grains.

Highlights

Zinc (Zn) as an essential micronutrient for all living organisms
We found that an Australian wild rice O. meridionalis had a higher grain Zn concentration
We found that the Australian wild accession O. meridionalis W1627 had the highest grain Zn concentration (68.3 ± 6.7 mg kg-1) among the wild and cultivated rice accessions examined

Summary

Introduction

Zinc (Zn) as an essential micronutrient for all living organisms. Zn is involved in many biochemical functions of proteins, lipids, and nucleic acids [1]. An insufficient level of Zn in human body causes multiple clinical manifestations (i.e., impaired immune function, growth retardation, hair loss, eye and skin lesions, and loss of appetite) [2]. Detection of QTLs controlling grain Zn concentration in rice using Oryza meridionalis. The Joint Research Program from the Institute of Plant Science and Resources, Okayama University, supported consumables and travel fee for the collaborative research between R.I and J.F. M. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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Results

Conclusion