Location: Children's Nutrition Research CenterTitle: Identification of putative target genes to manipulate Fe and Zn concentrations in rice grains) Author
Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2010
Publication Date: 11/15/2010
Citation: Sperotto, R.A., Boff, T., Duarte, G.L., Santos, L.S., Grusak, M.A., Fett, J.P. 2010. Identification of putative target genes to manipulate Fe and Zn concentrations in rice grains. Journal of Plant Physiology. 167(17):1500-1506. Interpretive Summary: Rice is the staple food of half of the world’s population; unfortunately, it is a poor source of essential micronutrients such as iron and zinc. If we had a better understanding of how these micronutrient metals moved within the plant, from leaf tissues to seeds, we could develop ways to improve the concentration of these nutrients in rice grains. The flag leaf is the uppermost leaf on the plant and is thought to play a major role in delivering mineral nutrients, including iron and zinc, to developing seeds. Because of this, we focused on flag leaves; to study 25 metal-related genes from rice to determine which of these genes were expressed (that is, turned on) in the flag leaves. We showed that the extent to which nine of the 25 genes were turned on in flag leaves was related to the concentration of iron and/or zinc that the diverse cultivars could achieve in their grains. Thus, our study has provided a short list of putative target genes that plant breeders could focus on to manipulate and elevate iron and zinc concentrations in rice grains.
Technical Abstract: Rice is the staple food of half of the world’s population; however, it is a poor source of essential micronutrients such as Fe and Zn. Since flag leaves are one of the sources of remobilized metals for developing seeds, the identification of the molecular players that might contribute to the process of metal transport from flag leaves to the seeds may be useful for biofortification purposes. We analyzed the expression of 25 metal-related genes from rice, including rice homologues for YSLs, NRAMPs, ZIPs, IRT1, VIT1 (coding for known or potential metal transporters), as well as, NASs, FROs and NAC5 (involved in metal homeostasis) in flag leaves of eight rice cultivars (showing contrasting levels of seed Fe and Zn) during panicle exertion (R3) and grain filling stage (R5). The expression level of nine of these genes (OsYSL6, OsYSL8, OsYSL14, OsNRAMP1, OsNRAMP7, OsNRAMP8, OsNAS1, OsFRO1, and OsNAC5) in flag leaves exhibited significant correlations with Fe and/or Zn concentrations in the seeds. In this way, our study has provided a short list of putative target genes to manipulate Fe and Zn concentrations in rice grains.