Distribution, accumulation and speciation of selenium at the different growth stages of four garlic clones

Selenium (Se) is an essential micronutrient for humans. Garlic (Allium sativum L.) metabolises Se into important Se-amino acids like Se-methylselenocysteine (Se-MetSeCys), precursor of methylselenol, an active species for cancer prevention. Therefore, the Se accumulation and speciation in garlic were studied to evaluate their relations with growth stages and types of plant clones. Four garlic clones (Nieve INTA, Union FCA, Gostoso INTA and Rubí INTA) were fortified with a Se solution (169 g Se L^-1). The association of Se to different molecular weight fractions was evaluated by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS) detection. Also, anion exchange chromatography (AEC-ICP-MS) was used for the determination of Se-amino acids, while their identification was performed by ESI-MS/MS. The Se was incorporated into high (7-5 kDa) and low (2-4 kDa) molecular weight fractions. The presence of Se-MetSeCys was observed mostly. Se-MetSeCys increased in bulbs to a maximum value but increased, then decreased, in leaves and roots. The Se-organic species were mostly found in bulbs in the last growth stage. Garlic showed a significant ability to accumulate and metabolise Se, specially, the red clones (Gostoso INTA and Rubí INTA). Also, this work suggests that this plant may become an attractive source of Se-amino acids with important biological properties.