Characterization of flavins in roots of Fe-deficient strategy I plants, with a focus on Medicago truncatula.
The root accumulation and excretion of riboflavin (Rbfl) and Rbfl derivatives have been studied in the model legume species Medicago truncatula, grown in hydroponics in two different Fe deficiency conditions, with and without CaCO(3). Using high resolution mass spectrometry techniques coupled to liquid chromatography, three different flavin derivatives not previously reported in plants, putatively identified as 7-hydroxy-Rbfl, 7α-hydroxy-Rbfl and 7-carboxy-Rbfl, were found along with Rbfl in Fe-deficient M. truncatula roots. In the presence of CaCO(3) most of the flavins were accumulated in the roots, whereas in the absence of CaCO(3) there was partial export to the nutrient solution. The major flavins in roots and nutrient solution were Rbfl and 7-hydroxy-Rbfl, respectively. Flavins were located in the root cortex and epidermal cells, preferentially in a root region near the apex that also exhibited increased ferric chelate reductase (FCR) activity. Six out of 15 different species of horticultural interest showed root increases in both Rbfl (four of them also having Rbfl derivatives) and FCR. No significant correlation was found between Rbfl and either phosphoenolpyruvate carboxylase or FCR activities, whereas the latter two showed a good correlation between them. The possible roles of Rbfl and Rbfl derivatives in roots and nutrient solutions are discussed. Medicago truncatula is proposed as a model system for flavin studies.
Plant Nutrition Department, Aula Dei Experimental Station, E-50080, Zaragoza, Spain.
Jorge
J
Rodríguez-Celma
Saúl
S
Vázquez-Reina
Jesús
J
Orduna
Anunciación
A
Abadía
Javier
J
Abadía
Ana
A
Álvarez-Fernández
Ana-Flor
AF
López-Millán
D000143:Acids / Q000378:metabolism; D001692:Biological Transport; D002851:Chromatography, High Pressure Liquid; D038181:FMN Reductase / Q000378:metabolism; D005415:Flavins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D005453:Fluorescence; D007477:Ions; D000090463:Iron Deficiencies; D013058:Mass Spectrometry; D046913:Medicago truncatula / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D010084:Oxidation-Reduction; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010802:Phylogeny; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000378:metabolism*; D025341:Principal Component Analysis; D012015:Reference Standards; D012256:Riboflavin / Q000378:metabolism; D012996:Solutions; D013045:Species Specificity; D013056:Spectrophotometry, Ultraviolet
D000143:Acids; D005415:Flavins; D007477:Ions; D010936:Plant Extracts; D012996:Solutions; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D010730:Phosphoenolpyruvate Carboxylase; D012256:Riboflavin