TY - JOUR

T1 - Loss of decreased-rubisco phenotype between generations of wheat transformed with antisense and sense rbcS

AU - Mitchell, Rowan A. C.

AU - Joyce, Priya A.

AU - Rong, Honglin

AU - Evans, Victoria J.

AU - Madgwick, Pippa J.

AU - Parry, Martin A. J.

PY - 2004/10

Y1 - 2004/10

N2 - The elite UK winter wheat cv. Riband was transformed with constructs containing rbcS in sense and antisense orientations driven by the maize ubiquitin promoter with a transformation efficiency of 1.2%. Of 77 primary transformants 31% of the sense-rbcS transformed lines and 78% of the antisense-rbcS transformed lines had decreased rubisco content compared to wild-type and marker-only controls, with decreases of up to 60%. However, in the T1 progeny which inherited the transgene, only 5% showed significantly decreased rubisco content and these effects were on the margins of significance. Five potential T2 homozygous lines from T1 parents which had transgene segregation consistent with a single locus were identified. There was no significant decrease in rubisco content relative to wild-type in any of these lines (LSD of 8% for P = 0.05). Expression of antisense rbcS transgenes in two of these T2 lines was low but was increased following exposure of the plants to 37°C for 48 h. However this did not induce a significant decrease in rubisco protein content relative to controls. Southern analysis of two antisense lines showed that they had low copy number and 1-2 insertion events. In one of the two lines there was increased methylation of the ubiquitin intron in T2 samples compared to the T0 primary transformant. Further work is required to establish whether methylation occurred in all the lines which lost the phenotype, and therefore the likelihood of this being the cause. The disappearance of the decreased rubisco-content phenotype between generations may therefore be attributable to (1) greater activity of the ubiquitin promoter due to greater stress in the T0 generation plants and/or (2) increased methylation of the transgene promoter region between generations.

AB - The elite UK winter wheat cv. Riband was transformed with constructs containing rbcS in sense and antisense orientations driven by the maize ubiquitin promoter with a transformation efficiency of 1.2%. Of 77 primary transformants 31% of the sense-rbcS transformed lines and 78% of the antisense-rbcS transformed lines had decreased rubisco content compared to wild-type and marker-only controls, with decreases of up to 60%. However, in the T1 progeny which inherited the transgene, only 5% showed significantly decreased rubisco content and these effects were on the margins of significance. Five potential T2 homozygous lines from T1 parents which had transgene segregation consistent with a single locus were identified. There was no significant decrease in rubisco content relative to wild-type in any of these lines (LSD of 8% for P = 0.05). Expression of antisense rbcS transgenes in two of these T2 lines was low but was increased following exposure of the plants to 37°C for 48 h. However this did not induce a significant decrease in rubisco protein content relative to controls. Southern analysis of two antisense lines showed that they had low copy number and 1-2 insertion events. In one of the two lines there was increased methylation of the ubiquitin intron in T2 samples compared to the T0 primary transformant. Further work is required to establish whether methylation occurred in all the lines which lost the phenotype, and therefore the likelihood of this being the cause. The disappearance of the decreased rubisco-content phenotype between generations may therefore be attributable to (1) greater activity of the ubiquitin promoter due to greater stress in the T0 generation plants and/or (2) increased methylation of the transgene promoter region between generations.

KW - Cereal transformation

KW - Nitrogen-use efficiency

KW - Photosynthesis

KW - Transgenic winter wheat

U2 - 10.1111/j.1744-7348.2004.tb00377.x

DO - 10.1111/j.1744-7348.2004.tb00377.x

M3 - Journal article

AN - SCOPUS:19544390102

VL - 145

SP - 209

EP - 216

JO - Annals of Applied Biology

JF - Annals of Applied Biology

SN - 0003-4746

IS - 2

ER -