Abstract

Sucrose was the predominant sugar in seeds of five cultivars of common bean (Phaseolus vulgaris L.) grown under controlled conditions. The concentration of soluble sugars was higher in seeds from nodulated plants than seeds from N-fertilized or control (uninoculated and unfertilized) plants. Trehalose was detected in seeds but only from nodulated plants, and average values ranged from undetectable levels in seeds from control plants to 18 mg kg⁻¹ in seeds from nodulated plants. Nodulated plants also produced larger and heavier seeds of higher quality; sucrose and trehalose contents were highly correlated with germination rate and with the vigor index of artificially aged seeds. Seeds of nine common bean cultivars grown in the field showed soluble sugar contents similar to those observed in seeds from nodulated plants raised in a growth chamber, except that the trehalose levels were significantly higher (23–111 mg kg⁻¹). Trehalose was not detected in seeds from non-nodulating control plants. Seed trehalose level was significantly correlated with germination rate and with the vigor index of artificially aged seeds. Seed glucose concentrations were negatively related to all of the seed quality parameters used. In general terms, the recognition of the natural presence of trehalose in seeds has been limited to reports on the expression of the trehalose biosynthetic genes in a few plants. Our data show that in seeds produced by nodulated bean, plants trehalose occurs at high levels, suggesting that strategies to maximize nodulation may result in improvement of seed quality.

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