Production of intraspecific aneuploids in the genus Solanum. III. Intraspecific aneuploids

Summary The triploids recovered from 4x×2x crosses in three Solanum species were very vigorous and although few seeds/fruit were obtained when the triploids were crossed to diploids, the extensive crossing programme produced sufficient seed of four species cph, chc, pnt and tar. The average seed set for the 3x-2x crosses was an extremely low 3.5 seeds/fruit.Approximately 90% of the progeny of the 3x–2x crosses were aneuploids with chromosome numbers of 2n=25–29. The frequency of the aneuploids in the three species that were studied was chc 93%, pnt 94% and tar 92%. The aneuploids of chc and tar were extremely vigorous and fertile and they were used as females in crosses to the marker stocks. The aneuploids of pnt were vigorous, but the crossability barrier of pnt prevented their use in crosses to the marker stocks. A number of the aneuploids produced seed upon being selfed, but the ability to produce self seed may be related to the pseudo-compatibility of the parental clones. In only 7 aneuploids was there an indication that the self fertility was due to overcoming the self-incompatibility barrier as a result of competition-interaction of the aneuploid gamete.Plants in the families from the triploid-diploid crosses had a tremendous amount of variation in morphological characteristics (leaf shape, size and color; berry shape, color and degree or verrucose spotting: and plant habit and vigor). A large portion of variation exhibited in these families was due to the normal genetic segregation of the heterozygous parents. It was impossible to distinguish the aneuploids from their diploid sibs especially those having only one or two additional chromosomes because they were as vigorous and fertile as the diploids.There were some preliminary indications of the existence of distinct morphological characteristics among the aneuploids (separate petals, long berries, and extreme verrucose berries). However, there was no indication that these traits were due to the dosage effect of the extra chromosome. If it should be determined that this was true, it would be extremely useful in associating genes with chromosomes and determining the phenotypic effects due to the presence of an additional chromosome.Cooperative investigations of the College of Agriculture and Life Sciences, University of Winconsin and the Agricultural Research Service, U.S. Department of Agriculture, Madison, Wisconsin. Supported in part by grants from the Research Committee of the Graduate School, University of Wisconsin.First and third author respectively, formally Graduate Research Assistant Department of Horticulture, University of Wisconsin, Madison, and Geneticist Agriculture Research Service, U.S. Department of Agriculture, University of Wisconsin, Madison. Present address: Department of Genetics. University of Wisconsin, Madison, Wisconsin 53706 and Head Breeding and Genetics Department, International Potato Center, Lima, Peru.     

Population structure of Phytophthora infestans in China – geographic clusters and presence of the EU genotype Blue_13

The population structure of Phytophthora infestans in China was studied and three mitochondrial haplotypes (Ia, IIa, IIb) were observed. Genetic analysis with 10 highly informative SSR markers identified 68 different genotypes, including three dominant clonal lineages. In the Chinese P. infestans population, the genotypes were strongly clustered according to their geographic origin. One of dominant clonal lineages was genetically similar to Blue_13, a dominant clonal lineage found in Europe since 2004. This is the first report of Blue_13 outside Europe. Only one mating type (A1) was found in the northern and southeastern provinces, but in southern and northwestern China both mating types were observed. The mating type ratio and SSR allele frequencies indicate that in China the sexual cycle of P. infestans is rare. These results emphasize that the migration of asexual propagules and the generation of subclonal variation are the dominant driving factors of the population structure of P. infestans in China. They may also have implications for the role of monitoring P. infestans populations in potato late blight management strategies in China.     

Variability of certain chemotypes in three accessions of German chamomile (Matricaria chamomilla L.)

In 203 analyzed chamomile plants, several compounds appreciated for their medicinal value, were evaluated qualitatively and quantitatively. α-Bisabolol and its oxides A and B were measured by gas chromatography; matricine as a precursor of chamazulene, was assessed semi-quantitatively by matching visually thin layer chromatography bands with a concentration range of the pure substance and the flavonoids apigenin and apigenin-7-glycoside were quantified by high performance liquid chromatography. Mean values of all compounds were compared in the three chamomile accessions ‘Manzana’, ‘Lutea’ and ‘Hungarian 2’. Correlations between different substances over all data were calculated. Moreover, certain groups combining particular properties according to their desired purpose or specificity, were formed. Their incidence in the particular chamomile varieties was determined. ‘Manzana’, a tetraploid cultivar, exhibited the highest share of the valuable bisabolol–matricine-type and the lowest ratio of bisabolol-oxides to bisabolol. To develop ‘high-quality-populations’, defined individuals of this cultivar shall be selected for further breeding.