Genetic engineering of plant architecture in wheat
Particle bombardment of immature scutella was used to generate multiple lines of transgenic wheat with either PHY A, PHYB or PHYC from Arabidopsis or PHY A from oat.;Responses of segregating transgenic seedlings to cFR light were used as a screen for biologically active lines. The 'short coleoptile' phenotype under cFR was shown to segregate with the oat PHYA transgene and rtPCR detection of transcript. All of the transgenic lines containing the Arabidopsis PHYA and several oat PHYA lines demonstrated phenotypes indistinct to wild-type, possibly demonstrating transcriptional silencing.;Biologically active lines with Mendelian segregation ratios of 3:1 were selected for further analysis and homozygous individuals for each identified by PCR. Southern analysis of selected lines demonstrated that all originated from a distinct transformation event and harboured at least a single intact copy of the transgene. The complexity of gene integration was related to observed gene dosage and silencing effects.;Adult transgenic plants under white light with high R:FR ratio, demonstrated an increased chlorophyll content, a reduced production of superfluous tillers, a reduction in sensitivity to shortened day-length and an increased developmental rate leading to a reduction in days to heading.;The transgenic lines demonstrated an altered response to shade. In addition to the phenotypes observed under white light, plant height was significantly reduced and harvest index increased compared to the nulls, these responses were distinct to the those observed under white light and suggest an altered response to reduced R:FR.;The results suggest that oat PHYA is biologically active in transgenic wheat and that over-expressing PHYA alters the responses of etiolated seedlings to cFR, the light grown morphology and development of adult plants, and the responses of the plants to shade.