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GrainGenes Reference Report: PNA-99-16325

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Reference	PNA-99-16325
Title	Transgenic barley grain overexpressing thioredoxin shows evidence that the starchy endosperm communicates with the embryo and the aleurone
Journal	Proceedings of the National Academy of Sciences, USA
Year	2002
Volume	99
Pages	16325-16330
Author	Wong JH [ Show all 8 ]
Abstract	Summary: Homozygous lines of barley overexpressing a wheat thioredoxin h transgene (up to 30-fold) were generated earlier by using a B1-hordein promoter with a signal peptide sequence for targeting to the protein body and found to be enriched in starch debranching enzyme (pullulanase). Here, we describe the effect of biochemically active, overexpressed thioredoxin h on germination and the onset of alpha-amylase activity. Relative to null segregant controls lacking the transgene, homozygotes overexpressing thioredoxin h effected (i) an acceleration in the rate of germination and appearance of alpha-amylase activity with a 1.6- to 2.8-fold increase in gibberellin A1 (GA1) content; (ii) a similar acceleration in the appearance of the alpha-amylase activity in deembryonated transgenic grain incubated with gibberellic acid; (iii) a 35% increase in the ratio of relative reduction (abundance of SH) of the propanol soluble proteins (hordein 1 fraction); and (iv) an increase in extractable and soluble protein of 5-12% and 11-35%, respectively. Thioredoxin h, which was highly reduced in the dry grain, was degraded in both the null segregant and homozygote after imbibition. The increase in alpha-amylase activity and protein reduction status was accompanied by a shift in the distribution of protein from the insoluble to the soluble fraction. The results provide evidence that thioredoxin h of the starchy endosperm communicates with adjoining tissues, thereby regulating their activities, notably by accelerating germination of the embryo and the appearance of alpha-amylase released by the aleurone
External Databases	Pubmed: 12456891
Keyword	acid [ Show all 28 ]

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