Using a model-based framework for analysing genetic diversity during germination and heterotrophic growth of Medicago truncatula.

BACKGROUND AND AIMS: The framework provided by an emergence model was used: (1) for phenotyping germination and heterotrophic growth of Medicago truncatula in relation to two major environmental factors, temperature and water potential; and (2) to evaluate the extent of genetic differences in emergence-model parameters. METHODS: Eight cultivars and natural accessions of M. trunculata were studied. Germination was recorded from 5 to 30 degrees C and from 0 to -0.75 MPa, and seedling growth from 10 to 20 degrees C. KEY RESULTS: Thermal time to reach 50 % germination was very short (15 degrees Cd) and almost stable between genotypes, while base temperature (2-3 degrees C) and base water potential for germination (-0.7 to -1.3 MPa) varied between genotypes. Only 35 degrees Cd after germination were required to reach 30 mm hypocotyl length with significant differences among genotypes. Base temperature for elongation varied from 5.5 to 7.5 degrees C. Low temperatures induced a general shortening of the seedling, with some genotypes more responsive than others. No relationship with initial seed mass or seed reserve distribution was observed, which might have explained differences between genotypes and the effects of low temperatures. CONCLUSIONS: The study provides a set of reference values for M. trunculata users. The use of the ecophysiological model allows comparison of these values between such non-crop species and other crops. It has enabled phenotypic variability in response to environmental conditions related to the emergence process to be identified. The model will allow simulation of emergence differences between genotypes in a range of environments using these parameter values. Genomic tools available for the model species M. trunculata will make it possible to analyse the genetic and molecular determinants of these differences.

Chemical composition and antioxidant potential of Ruta montana L. essential oil from Algeria.

The essential oil of aerial parts of Ruta montana L. growing in the Oran region in the west of Algeria was obtained by hydrodistillation with a 1.63% yield on a dry weight basis. Gas chromatography (GC) and GC/mass spectrometry (MS) analyses were carried out to identify the chemical composition of R. montana essential oil. Moreover, spectrophotometric analyses were employed to highlight the scavenger capacity of this oil using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. Twenty compounds were identified by GC and CG/MS analyses, and the bulk of the compounds of the oil were undecan-2-one (32.8%), nonan-2-one (29.5%), nonanol-2-acetate (18.2%), and psoralen (3.5%). The results obtained using the DPPH test show that R. montana essential oil possesses antiradical activity in a concentration-dependent manner. Thus, a linear correlation (correlation coefficient R(2) = 0.971, P < .001) was found between the reduction of DPPH stable free radical and the concentration of R. montana essential oil.