Export of defensive glucosinolates is key for their accumulation in seeds

• Published in: Nature (London) Vol. 617; no. 7959; pp. 132 - 138
• Main Authors: Xu, Deyang, Sanden, Niels Christian Holm, Hansen, Line Lykke, Belew, Zeinu Mussa, Madsen, Svend Roesen, Meyer, Lasse, Jørgensen, Morten Egevang, Hunziker, Pascal, Veres, Dorottya, Crocoll, Christoph, Schulz, Alexander, Nour-Eldin, Hussam Hassan, Halkier, Barbara Ann
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-05-2023; Nature Publishing Group
• Subjects: 14/19; 42; 42/35; 45/61; 45/70; 45/77; 631/449/2169; 631/449/2667; 631/449/447/2311; 631/449/448/2651; 64/114; 82/58; Accumulation; Amino acids; Apoplast; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Crops; Defense; Efflux; Electrochemistry; Exports; Glucosinolates; Glucosinolates - metabolism; Homeostasis; Humanities and Social Sciences; Localization; Low level; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Metabolites; multidisciplinary; Mutation; Nutritive value; Oilseed crops; Oilseeds; Phloem - metabolism; Reproducibility of Results; Science; Science (multidisciplinary); Seeds; Seeds - metabolism; Translocation
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-023-05969-x

Plant membrane transporters controlling metabolite distribution contribute key agronomic traits
1
–
6
. To eliminate anti-nutritional factors in edible parts of crops, the mutation of importers can block the accumulation of these factors in sink tissues
7
. However, this often results in a substantially altered distribution pattern within the plant
8
–
12
, whereas engineering of exporters may prevent such changes in distribution. In brassicaceous oilseed crops, anti-nutritional glucosinolate defence compounds are translocated to the seeds. However, the molecular targets for export engineering of glucosinolates remain unclear. Here we identify and characterize members of the USUALLY MULTIPLE AMINO ACIDS MOVE IN AND OUT TRANSPORTER (UMAMIT) family—UMAMIT29, UMAMIT30 and UMAMIT31—in
Arabidopsis thaliana
as glucosinolate exporters with a uniport mechanism. Loss-of-function
umamit29
umamit30
umamit31
triple mutants have a very low level of seed glucosinolates, demonstrating a key role for these transporters in translocating glucosinolates into seeds. We propose a model in which the UMAMIT uniporters facilitate glucosinolate efflux from biosynthetic cells along the electrochemical gradient into the apoplast, where the high-affinity H
+
-coupled glucosinolate importers GLUCOSINOLATE TRANSPORTERS (GTRs) load them into the phloem for translocation to the seeds. Our findings validate the theory that two differently energized transporter types are required for cellular nutrient homeostasis
13
. The UMAMIT exporters are new molecular targets to improve nutritional value of seeds of brassicaceous oilseed crops without altering the distribution of the defence compounds in the whole plant.
Arabidopsis thaliana
UMAMIT uniporters facilitate glucosinolate efflux from biosynthetic cells along the electrochemical gradient into the apoplast, in which the high-affinity H
+
-coupled glucosinolate importers GLUCOSINOLATE TRANSPORTERS (GTRs) load them into the phloem for translocation to the seeds.