Entwicklung von Maissorten mit spezieller Anpassung an die Bedingungen des Ökologischen Landbaus

Organic farming has gained in importance in Germany during the past years. Therefore an increasing demand exists for varieties with specific adaptation to this farming system. Hence it becomes necessary for plant breeders to optimize their selection strategy for varieties which meet the requirements of organic farming. For this purpose a research project was conducted at the University of Hohenheim, Institute of Plant Breeding, Seed Science, and Population Genetics in cooperation with the KWS SAAT AG. It was supported by the “Bundesprogramm Ökologischer Landbau” and lasted from April 2004 to December 2006. In the present contribution the results of comparative trials with maize under organic and conventional farming conditions in 2004 and 2005 are reported. It is demonstrated that under organic farming maize genotypes can be evaluated with similar precision as under conventional conditions. However, inconsistent correlations between the two farming systems indicate that the predictability of performance under organic farming from data obtained under conventional farming and vice versa strongly depends on the genetic materials

Association mapping reveals gene action and interactions in the determination of flowering time in barley

The interaction between members of a gene network has an important impact on the variation of quantitative traits, and can influence the outcome of phenotype/genotype association studies. Three genes (Ppd-H1, HvCO1, HvFT1) known to play an essential role in the regulation of flowering time under long days in barley were subjected to an analysis of nucleotide diversity in a collection of 220 spring barley accessions. The coding region of Ppd-H1 was highly diverse, while both HvCO1 and HvFT1 showed a rather limited level of diversity. Within all three genes, the extent of linkage disequilibrium was variable, but on average only moderate. Ppd-H1 is strongly associated with flowering time across four environments, showing a difference of five to ten days between the most extreme haplotypes. The association between flowering time and the variation at HvFT1 and HvCO1 was strongly dependent on the haplotype present at Ppd-H1. The interaction between HvCO1 and Ppd-H1 was statistically significant, but this association disappeared when the analysis was corrected for the geographical origin of the accessions. No association existed between flowering time and allelic variation at HvFT1. In contrast to Ppd-H1, functional variation at both HvCO1 and HvFT1 is limited in cultivated barley

Verminderung gefährlicher Alkaloide in der Nahrungskette durch die züchterische Verbesserung der Mutterkorn-Resistenz von Roggen

Roggen ist als Fremdbefruchter besonders anfällig für einen Befall mit Mutterkorn, der durch eine Infektion mit dem Schadpilz Claviceps purpurea (Fr.) Tul. hervorgerufen wird. Ziele dieser Studie waren die Suche nach effektiven Resistenzträgern gegen Mutterkorn aus genetischen Ressourcen, die Untersuchung der Vererbung von selbstfertilen Roggenmaterialien sowie die Analyse der Wechselwirkungen von Wirtsgenotyp und Mutterkornpilz hinsichtlich der Zusammensetzung und Toxizität der Alkaloide. Zur Untersuchung der Anfälligkeit, von Wirtspflanzen war es notwendig mit CMS (Cytoplasmatic Male-Sterile) Material zu arbeiten. Über drei Jahre wurden an zwei bzw. drei Standorten 75 selbstfertile CMS-Linien und 126 CMS-Einfachkreuzungen sowie 90 Testkreuzungen mit Genetischen Ressourcen deutscher, polnischer und russischer Herkunft. unter ökologischen Bedingungen angebaut, künstlich inokuliert und auf Mutterkornresistenz geprüft. Die Genetischen Ressourcen zeigten nicht in allen Fällen signifikante genotypische Unterschiede. Vor allem im deutschen geprüften Material war keine Signifikanz nachweisbar. Die Linien hatten geringere Mutterkorngewichte als die CMS-Einfachkreuzungen und zeigten immer signifikante genotypische Varianzen, die Einfachkreuzungen in den meisten Fällen. Die Korrelation zwischen beiden Materialgruppen war nur in den ersten beiden Jahren signifikant (r=0,6-0,7; P=0,01). Der mittlere Gesamtalkaloidgehalt der Linien war bei niedrigeren Mutterkorngewichten um ca. 25 % höher als bei den Einfachkreuzungen. Die genotypischen Varianzen für Alkaloide waren bei allen Experimenten und Materialien nicht oder nur schwach signifikant. Die Alkaloidgehalte erwiesen sich als kaum vom geprüften Roggentyp abhängig; aber zeigten starke umweltbedingte Unterschiede. Die Ergebnisse zeigen dass auch im selbstfertilen Material eine gezielte Resistenzselektion möglich ist. Aufgrund quantitativer Vererbung der Resistenz und hoher Genotyp x Umwelt-Wechselwirkungen ist dies allerdings noch ein langer Weg

Increasing Seed Viability of Maize Haploid Inducing Lines by Genetic and Non-Genetic Approaches

Some haploid inducing lines used in the production of maize doubled haploids (DHs), express germination problems and reduced vigor. In this study, haploid inducing lines RWS, RWK-76 and their reciprocal hybrids RWS/RWK-76 and RWK-76/RWS were examined for viability by Tetrazolium (TZ) and germination ability by standard germination tests. Evaluation based on TZ tests showed that 59% of the seed of RWK-76/RWS were not viable, compared with only 12% dead seed in RWS/RWK-76. Similarly, the percentage and speed of germination in RWK- 76/RWS (25%, 1.53) was lower than for RWS/RWK-76 (74%, 4.30). In an effort to develop a quick method for assessing seed viability in these lines, the TZ test was repeated in a different way. Seed from each genotype was placed in beakers containing distilled water.Seed would either float or sink. Subsequent TZ testing confirmed that seed that floated was dead, and seed that sank was alive, although some of them had defective embryos. The dead seed in both genotypes failed to develop an embryo, leaving an empty cavity that would fill with air and cause seed to float on water. This feature can be exploited for a simple and practical method to separate living from dead seed. In addition, we surveyed theig1 (indeterminate gametophyte) gene as a candidate for germination problems in inducer lines.Sequencing data from theig1 region showed that RWS and RWK-76 differed in one nucleotide and amino acidin the firstexon of ig1.Segregation of ig1 alleles from RWS and RWK-76 wassignificantly (P=0.01) distortedin the respectiveF2 population relative to the expected Mendelian segregation ratio (1:2:1). Thus, either ig1 or a linked gene in the ig1 region affect seed viability