Thymocytes were used as a model system to study the effect of microenvironmental pH changes on the radiation-induced apoptosis. We found that the sensitivity of thymocytes toward radiation induced apoptosis is increased by increasing the pH of the incubation medium. The major sensitivity change occurs between pH 7 and 8.
In a given cell suspension the results obtained where similar when the apoptosis evaluation was carried out either by counting the picnotic nuclei, or monitoring the fraction of apoptotic nuclei by flow cytometry; both methods show a radiosensitization when the pH value of incubation media rises from 7 to 8. These results may be important when “in vitro” experiments are performed with lymphoid cells, since changes in pH of the media may determine important changes in the results.
Spanish sunflower acreage is basically divided into three main and isolated areas, the Guadalquivir valley, southern Spain, represents 37% of the total acreage, the Cuenca area located in Spain´s central plateau, 28%, and the Castilla-León area, northern Spain, 29%. Sunflower broomrape (Orobanchecumana Wallr.) has been present in Spain since the 1960’s. From that time on, different waves of dissemination and dispersion of the parasite have been registered. The latest correspond to the broomrape race E dispersal in the early 1990’s and race F dispersal in the first few years of this century. These broomrape dissemination waves have been limited only to the Guadalquivir and Cuenca areas. In the Castilla-León area, the presence of broomrape had not been noticed until now.
In 2008, a highly virulent broomrape infection focal point (about 300 m2) was detected in a sunflower plot near Medina del Campo (Valladolid), south of the center of the Castilla-León area. Racial determination has proved that this broomrape inoculum belongs to race F.
Much research has been conducted to identify sources of genetic resistance to sunflower broomrape (Orobanche cumana Wallr.) and to study their mode of inheritance. However, studies on the parasite have been scarce. This manuscript reviews three genetic studies in sunflower broomrape. First, the inheritance of the absence of pigmentation in a natural mutant of this species with yellow plant color phenotype was studied. In a first stage, lines from the unpigmented mutant and a normally pigmented population were developed by several generations of self-pollination. Plants of both lines were crossed and the F1, F2, and F3 generations were evaluated. The results indicated that plant pigmentation is controlled by a partially dominant allele at a single locus. Second, the unpigmented mutant was used to evaluate outcrossing potential of the species. Two experiments in which single unpigmented plants were surrounded by normally pigmented plants were conducted under pot and field conditions. The cross-fertilization rate was estimated as the percentage of F1 hybrids in the progenies of unpigmented plants, which averaged 21.5% in the pot and 28.8% in the field experiment. The results indicated that, under the conditions of this study, the species was not strictly self-pollinated. Finally, the inheritance of avirulence was studied in crosses of plants from lines of O. cumana races E and F, developed by several generations of self-pollination. The F1 and F3 generations were evaluated on the differential line P-1380 carrying the race-E resistance gene Or5. The results suggested that race E avirulence and race F virulence on P-1380 are allelic and controlled by a single locus, which confirmed the gene-for-gene theory for the O. cumana–sunflower interaction.