A method of modifying the amount of at least one biochemical component in a plant comprising expressing Qua-Quine Starch (QQS) in the plant, the wild-type of which does not express QQS; a transgenic plant, or part thereof, which comprises and expresses QQS as a transgene and in which the amount of at least one biochemical component is modified; a tissue culture of regenerable cells of the transgenic plant; a vector comprising a nucleotide sequence, which encodes the coding sequence of QQS, operably linked to a non-native promoter, which promotes expression of the nucleotide sequence in a plant, which is other than Arabidopsis; and a method of producing a food or industrial product from a plant.