#100-16 Biosynthesis of phytosiderophores in graminaceous plants: divergent functions for their specific environments of iron nutrient

Iron (Fe) is an essential micronutrient to life. Different lives evolved different strategies efficient for its uptake and survival. Graminaceous plants evolved to secrete organic compounds, Phyto-Siderophores (PSs) for Fe uptake. The diversity of PSs in barley, oats, and rye provides plant tolerance to Fe deficiency. Rice, a Fe deficiency sensitive staple crop lacks PS diversity. The dioxygenase enzyme, Iron Deficiency Specific (IDS) catalyzing the reaction was reported almost 20 years ago in barley. In our study, we discovered the IDS homologs in rice. The functional analysis of the gene shows a similar expression and localization of the enzyme as barley. Further, the overexpression transgenic rice plants show tolerance to Fe deficiency and have induced Fe deficiency responsive metabolites content. However, no diverse PSs are observed indicating the rice enzyme plays a different unknown function than the barley enzyme. The results show high Fe accumulation in rice seeds indicating its potential in biofortification programs and breeding. Further study of this enzyme will elucidate the specific metabolic reaction predicted to be downstream in the metabolic pathway. This will help understand the evolutionary mechanism behind the diverse role of the enzyme in different graminaceous plants.

Keywords: Mugineic acids, vesicle-like structure, LC-ESI-Q-TOF-MS/MS