Ecological and evolutionary drivers of phenotypic and genetic variation in the European crabapple [Malus sylvestris (L.) Mill.], a wild relative of the cultivated apple.

BACKGROUND AND AIMS: Studying the relationship between phenotypic and genetic variation in populations distributed across environmental gradients can help us to understand the ecological and evolutionary processes involved in population divergence. We investigated the patterns of genetic and phenotypic diversity in the European crabapple, Malus sylvestris, a wild relative of the cultivated apple (Malus domestica) that occurs naturally across Europe in areas subjected to different climatic conditions, to test for divergence among populations. METHODS: Growth rates and traits related to carbon uptake in seedlings collected across Europe were measured in controlled conditions and associated with the genetic status of the seedlings, which was assessed using 13 microsatellite loci and the Bayesian clustering method. Isolation-by-distance, isolation-by-climate and isolation-by-adaptation patterns, which can explain genetic and phenotypic differentiation among M. sylvestris populations, were also tested. KEY RESULTS: A total of 11.6 % of seedlings were introgressed by M. domestica, indicating that crop-wild gene flow is ongoing in Europe. The remaining seedlings (88.4 %) belonged to seven M. sylvestris populations. Significant phenotypic trait variation among M. sylvestris populations was observed. We did not observe significant isolation by adaptation; however, the significant association between genetic variation and the climate during the Last Glacial Maximum suggests that there has been local adaptation of M. sylvestris to past climates. CONCLUSIONS: This study provides insight into the phenotypic and genetic differentiation among populations of a wild relative of the cultivated apple. This might help us to make better use of its diversity and provide options for mitigating the impact of climate change on the cultivated apple through breeding.

Simultaneous mineralization of glyphosate and diuron by a consortium of three bacteria as free- and/or immobilized-cells formulations.

A bacterial consortium able to mineralize two herbicides, glyphosate (Pseudomonas 4ASW) and diuron (Arthrobacter sp. N4 and Delftia acidovorans), was cultivated in both a synthetic culture medium without phosphate and a sediment extract medium. In the aim at optimizing glyphosate and diuron mineralization, all the combinations, i.e., free and/or immobilized cells in Ca-alginate beads were tested. With the synthetic medium, the simultaneous mineralization of glyphosate and diuron required at least the immobilization of Pseudomonas 4ASW. Conversely, with the sediment extract medium, only the mineralization of diuron was observed, most probably, because of both nutrient deficiency and phosphate in the sediment extract medium.

Mineralization of diuron [3-(3,4-dichlorophenyl)-1, 1-dimethylurea] by co-immobilized Arthrobacter sp. and Delftia acidovorans.

Mineralization of diuron has not been previously demonstrated despite the availability of some bacteria to degrade diuron into 3,4-dichloroaniline (3,4-DCA) and others that can mineralize 3,4-DCA. A bacterial co-culture of Arthrobacter sp. N4 and Delftia acidovorans W34, which respectively degraded diuron (20 mg l(-1)) to 3,4-DCA and mineralized 3,4-DCA, were able to mineralize diuron. Total diuron mineralization (20 mg l(-1)) was achieved with free cells in co-culture. When the bacteria were immobilized (either one bacteria or both), the degradation rate was higher. Best results were obtained with free Arthrobacter sp. N4 cells co-cultivated with immobilized cells of D. acidovorans W34 (mineralization of diuron in 96 h, i.e., 0.21 mg l(-1 )h(-1) vs. 0.06 mg l(-1 )h(-1) with free cells in co-culture).

Emergence and growth of hybrids between Brassica napus and Raphanus raphanistrum.

• Risk assessment studies of transgenic crops have recently brought evidence of a low spontaneous hybridization frequency of Brassica napus with Raphanus raphanistrum. The fate of the first generation hybrids is crucial to determine the initial rate of spread of transgenes. • This work aims to compare the fitness components of parents and F1 hybrids at the first step of the life cycle. The ability to emerge, establish seedling, cover the soil and develop adult plant was examined in controlled and field conditions, alone or in competition. • The F1 hybrids showed a lower seedling emergence, a significant delay of emergence, and a lower survival than for both parents. Rosette diameter and dry matter of hybrid plants were very reduced compared with those of both parents, especially when they grew in the field and under competition conditions. • The relevance of these results to gene flow and possible impact to agriculture and environment is discussed.