Abstract: Disclosed are stable recombinant multi-gene nucleic acid constructs, such as plant binary vectors, comprising (i) a gene encoding &ggr;-glutamylcysteine synthetase and (ii) a gene encoding glutathione synthetase, plus preferably at least one, preferably two, genes which encode enzymes involved in the redox cycling of glutathione between its reduced and its oxidised forms e.g. glutathione reductase and/or glutathione peroxidase. Preferably the promoters linked to the genes are different and of different strengths, and may optionally be inducible. Also provided are related materials and corresponding methods and uses e.g. in plants to improve oxidative stress tolerance enhance root development, or to increase the post-harvest shelf life of the plant or part thereof.

Abstract: Plant cells are transformed by:(i) transforming a plant cell whose growth is sensitive to inhibition by a sulfonamide or a salt thereof with a chimaeric gene comprising (a) a plant promoter, (b) a sulfonamide resistance gene having a sequence encoding a transit peptide fused to the 5'-end of the resistance gene and (c) a plant polyadenylation/terminator sequence;(ii) selecting a transformed plant cell whose growth is resistant to inhibition by a sulfonamide or salt thereof;(iii) optionally, regenerating from the transformed plant cell a genetically transformed plant which exhibit the said resistance;(iv) optionally, obtaining seed from the regenerated plant; and(v) optionally, propagating plants from the seed.The growth of weeds can be controlled at a locus where a transgenic plant obtained as above is being cultivated by applying to the locus an effective amount of a herbicide, such as asulam, which acts by inhibiting dihydropteroate synthase.