Transformation of maize with the p1 transcription factor directs production of silk maysin, a corn earworm resistance factor, in concordance with a hierarchy of floral organ pigmentation

The maize p1 gene encodes an R2R3-MYB transcription factor that controls the biosynthesis of red flavonoid pigments in floral tissues of the maize plant. Genetic and quantitative trait locus analyses have also associated the p1 gene with the synthesis of maysin, a flavone glycoside from maize silks that confers natural resistance to corn earworm. Here, we show directly that the p1gene induces maysin accumulation in silk tissues. Transformation of maize plants that had low or no silk maysin with p1 transgenes elevated silk maysin concentrations to levels sufficient for corn earworm abiosis. The p1 transgenes also conferred red pigment to pericarp, cob, husk and tassel tissues, as expected; however, different subsets of these tissues were pigmented within individual transgenic plants. Statistical analysis shows that the pigmentation patterns observed amongst the p1 transgenic plants conform to a hierarchy that is similar to the temporal ordering of floral organ initiation. We propose that the observed hierarchy of pigmentation patterns is conferred by variation due to epigenetic control of the p1 transgenes. The production of plants with improved traits through genetic engineering can depend in large part on the achievement of tight organ-specific expression of the introduced transgenes. Our results demonstrate that the production of transgenic plants using a promoter with well-defined tissue specificity, such as the p1 promoter, can result in unexpected variation in tissue specificity amongst the resulting transgenic plants

clinical and psychometric validation of the bresas questionnaire for symptom assessment among breast cancer survivors

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Genomic comparisons reveal biogeographic and anthropogenic impacts in the koala (Phascolarctos cinereus): a dietary-specialist species distributed across heterogeneous environments

The Australian koala is an iconic marsupial with highly specific dietary requirements distributed across heterogeneous environments, over a large geographic range. The distribution and genetic structure of koala populations has been heavily influenced by human actions, specifically habitat modification, hunting and translocation of koalas. There is currently limited information on population diversity and gene flow at a species-wide scale, or with consideration to the potential impacts of local adaptation. Using species-wide sampling across heterogeneous environments, and high-density genome-wide markers (SNPs and PAVs), we show that most koala populations display levels of diversity comparable to other outbred species, except for those populations impacted by population reductions. Genetic clustering analysis and phylogenetic reconstruction reveals a lack of support for current taxonomic classification of three koala subspecies, with only a single evolutionary significant unit supported. Furthermore, similar to 70% of genetic variance is accounted for at the individual level. The Sydney Basin region is highlighted as a unique reservoir of genetic diversity, having higher diversity levels (i.e., Blue Mountains region; AvHe(corr)-0.20, PL% = 68.6). Broad-scale population differentiation is primarily driven by an isolation by distance genetic structure model (49% of genetic variance), with clinal local adaptation corresponding to habitat bioregions. Signatures of selection were detected between bioregions, with no single region returning evidence of strong selection. The results of this study show that although the koala is widely considered to be a dietary-specialist species, this apparent specialisation has not limited the koala's ability to maintain gene flow and adapt across divergent environments as long as the required food source is available

Fluctuation of phytoecdysteroids in developing shoots of Taxus cuspidata

Phytoecdysteroids from the vegetative shoots of Taxus cuspidate, an evergreen shrub, were found to fluctuate at different developmental stages during shoot growth. The quantity of ecdysterone (2β,3β,14α,20R,22R,25-hexahydroxy-5β-cholest-7-en-6-one) was 47±5 mg/kg fresh weight, while the quantity of ponasterone A (2β,3β,14α,20R,22R-pentahydroxy-5β-cholest-7-en-6-one) was 23 mg/kg from leaves of one- to two-year-(52-104 week) old shoots. One-, four-, 18- and 37-week-old leaves and soft shoots contained, on a fresh weight basis, respectively, 56, 52, 114 and 127 mg/kg of ecdysterone and 2, 2, 23 and 15 mg/kg of ponasterone A. These results indicate that ecdysteroid accumulation is dynamic and possibly driven by cycles of synthesis, transport, and degradation. © 1990