Purine permease 5 contributes to riboflavin distribution in Arabidopsis reproductive organs
Shibata, R.; Kuwata, H.; Sugimoto, T.; Kikuchi, M.; Ishikawa, T.; Ogawa, T.
Plant Signaling
Watching a silique swell on your radish or mustard plant, you're witnessing a molecular tug-of-war over nutrients — and this discovery names one of the proteins deciding how much vitamin B2 those seeds actually receive, a first step toward understanding why some seeds are more nutritionally packed than others.
Plants need vitamin B2 to power their cells, but scientists didn't know how plants move it from place to place. This study found a specific protein that acts like a doorman for riboflavin at the cell surface, controlling how much gets into flowers and seeds. When researchers disabled that protein, vitamin B2 piled up abnormally in the plant's reproductive parts — proof that plants deliberately manage where this nutrient travels rather than letting it wander on its own.
Key Findings
AtPUP5, a plasma membrane protein, transports riboflavin and (less efficiently) FMN into cells, but struggles to move FAD, suggesting selectivity among related vitamin B2 forms.
Plants lacking AtPUP5 accumulate excess riboflavin specifically in reproductive organs — flowers, seed pods, and seeds — regardless of whether extra riboflavin was supplied externally.
AtPUP5 is not required for whole-plant riboflavin uptake, showing its role is spatially specific: local redistribution within reproductive tissues, not global absorption.
chevron_right Technical Summary
Scientists discovered a protein in Arabidopsis (thale cress) that acts as a traffic controller for riboflavin (vitamin B2), steering how much of it reaches flowers, seed pods, and seeds. Without this protein, riboflavin over-accumulates in reproductive organs — revealing that plants actively regulate where this essential nutrient goes, rather than letting it diffuse freely.
Abstract Preview
Riboflavin (vitamin B{square}; RF) and its derivatives flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are indispensable cofactors for redox reactions in plants. While higher plan...
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Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed.