Antisense suppression of deoxyhypusine synthase by vacuum‐infiltration of Agrobacterium enhances growth and seed yield of canola

Abstract

Deoxyhypusine synthase (DHS; EC 2.5.1.46) mediates the first of two enzymatic reactions that convert inactive eukaryotic translation initiation factor‐5A (eIF‐5A) to an activated form, thought to facilitate translation. A full‐length cDNA clone encoding canola (Brassica napus cv. Westar) DHS was isolated from a cDNA‐expression library prepared from senescing leaves. Transgenic canola lines with suppressed DHS expression were obtained by introducing a transgene expressing antisense 3′‐UTR canola DHS cDNA under the regulation of the constitutive cauliflower mosaic virus 35S (CaMV‐35S) promoter. Transformed seed was obtained by vacuum infiltration of canola inflorescences using the protocol developed for Arabidopsis with modifications. The resultant transgenic plants had reduced levels of leaf DHS protein and exhibited delayed natural leaf senescence. Suppression of DHS also increased leaf size by 1.5‐ to two‐fold and resulted in increases in seed yield of up to 65%. Moreover, the enhanced performance of transgenic plants reflected increased tolerance to chronic sublethal stress. When wild‐type and transgenic plants were grown in 6‐inch pots, the increase in seed yield accruing from suppression of DHS was approximately 4.5‐fold greater than when the plants were grown in 12‐inch pots. Thus, suppression of DHS appears to ameliorate the effects of sublethal stress engendered by growth in small containers.