Jürgen Odermatt

Influence of over-expression of the FLOWERING PROMOTING FACTOR 1 gene (FPF1) from Arabidopsis on wood formation in hybrid poplar (Populus tremula L. × P. tremuloides Michx.)

Constitutive expression of the FPF1 gene in hybrid aspen (Populus tremula L. × P. tremuloides Michx.) showed a strong effect on wood formation but no effect on flowering time. Gene expression studies showed that activity of flowering time genes PtFT1, PtCO2, and PtFUL was not increased in FPF1 transgenic plants. However, the SOC1/TM3 class gene PTM5, which has been related to wood formation and flowering time, showed a strong activity in stems of all transgenic lines studied. Wood density was lower in transgenic plants, despite significantly reduced vessel frequency which was overcompensated by thinner fibre cell walls. Chemical screening of the wood by pyrolysis GC/MS showed that FPF1 transgenics have higher fractions of cellulose and glucomannan products as well as lower lignin content. The latter observation was confirmed by UV microspectrophotometry on a cellular level. Topochemical lignin distribution revealed a slower increase of lignin incorporation in the developing xylem of the transgenics when compared with the wild-type plants. In line with the reduced wood density, micromechanical wood properties such as stiffness and ultimate stress were also significantly reduced in all transgenic lines. Thus, we provide evidence that FPF1 class genes may play a regulatory role in both wood formation and flowering in poplar.

Approaches to applying internal standards for the quantification of paper additives by Py-GC/MSD

Abstract In the present study, five different methods of internal standard (IS) application with different IS substances were used for the quantification of typical chemical additives in paper such as wet strength or sizing agents by the combination of analytical pyrolysis with gas chromatographic separation and mass selective detection (Py-GC/MSD). The advantages and disadvantages are described. One approach only followed variations of the response of the MSD. A further approach, the injection of an IS solution within the pyrolyzer interface, compensated for variations only in the GC/MSD part. In the other three approaches the IS followed the whole analytical pathway. When different IS applications in the same run were used, sources for variations could be identified. The best reproducibility with relative standard deviations (RSDs) of 4–8% for the paper additives was obtained by using degradation products from the cellulosic matrix as internal standards. The shortcoming of this approach is that the matrix has to be known. Solutions to solve this problem are demonstrated.