Poster Presentation International Plant Molecular Biology Conference 2024

Activation of the FERRITIN2 gene in rice endosperm by an adjacent 35S enhancer (#153)

Ting-Iun Nieh 1 , Chih-Yun Chen 1 , Shu-Heng Chang 1 , Wilhelm Gruissem 1
  1. National Chung Hsing University, South Dist., TAICHUNG CITY, Taiwan

Rice is one of the most important staple foods. The polished grain contains a high amount of starch, which provides calories for half of the world population. But polished rice lacks micronutrients such as iron or zinc that are essential for human health and can lead to severe malnutrition when missing in the diet. Biofortification is an effective strategy to increase micronutrient content in rice grains. The FERRITIN protein, which can store up to 4500 iron atoms, is often used in iron biofortification. Overexpressing FERRITIN in rice endosperm can increase the iron level in rice grains. We have identified a Taiwan Rice Insertional Mutant (TRIM) line M0096585 with a T-DNA inserted 69 bp downstream of the OsFER2 3’-UTR with the CaMV 35S enhancer in the anti-sense orientation. The mutant line has a similar phenotype as wild type rice. OsFER2 expression is strongly upregulated in the flag leaf and activated in the endosperm of M0096585. Furthermore, the expression of six other genes located within 10 kb up- and downstream of the T-DNA insertion site is upregulated, indicating that the CaMV35S enhancer acts as a cis-activating element. Despite the high level of OsFER2 expression in the M0096585 endosperm tissue, the iron level was not increased compared to wild type endosperm. Since OsFER2 gene expression is increased in other tissues as well, rice iron homeostasis is likely not affected and any surplus iron is sequestered by FER2, which could explain why iron is not increased in the M0096585 endosperm.

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