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

Estimation of general and specific combining ability variances and their implications on hybrid rye breeding.

Effects and variances of general (GCA) and specific (SCA) combining ability have been estimated from two experiments. For the first experiment (EXP 1) 19 homozygous lines originating from the Petkus pool were crossed with two CMS single cross testers derived from the Petkus pool (intra-pool test crosses) and with two testers from the Carsten-Danko pool (inter-pool test crosses), respectively. In the year 2000 grain yield was measured at 5 locations in Germany. The second experiment (EXP II) comprised a factorial of inter-pool crosses by using 4 homozygous CMS Petkus pool lines as seed parents and 6 Carsten-Danko lines as pollen parents. The respective 24 inter-pool crosses were evaluated for grain yield on several locations in 1996 and 1998.In EXP I GCA-variance of candidate lines (4.7 —5.9 q/ha2 was estimated to have a similar size as SCA-variance. Possible reasons for an overestimation of SCA-variance are extreme divergence between testers, insufficient removal of inbreeding effects in the intra-pool test crosses and bias due to SCA × year interaction-variance. The use of intra-pool testers should be restricted to breeding material where inbreeding due to consanguinity between testers and candidate lines is either absent or will evenly affect test cross performance of all candidates.In EXP II GCA-variances for female 9.2 q/ha2 and male 2.4 q/ha2 lines were much higher than SCA-variance. Repeatability for GCA-effects over different environments was medium (r=0.67), whereas for SCA-effects it was low (r=0.13). Selection intensity for yield should therefore be moderate, if based on a single year of testing only. Selection of parental components for hybrids and prediction of hybrid performance should mainly base on GCA-effects. Alternative to the use of factorial crosses test crosses with testers representing the opposite pool are recommended. Testing for SCA-effects and for SCA x environment interaction- effects can be a valuable diagnostic tool, to become aware of strengths and weaknesses of the elite material used to build new hybrids. SCA-tests should therefore be performed by using highly divergent environments

Estimation of general and specific combining ability variances and their implications on hybrid rye breeding.

Effects and variances of general (GCA) and specific (SCA) combining ability have been estimated from two experiments. For the first experiment (EXP 1) 19 homozygous lines originating from the Petkus pool were crossed with two CMS single cross testers derived from the Petkus pool (intra-pool test crosses) and with two testers from the Carsten-Danko pool (inter-pool test crosses), respectively. In the year 2000 grain yield was measured at 5 locations in Germany. The second experiment (EXP II) comprised a factorial of inter-pool crosses by using 4 homozygous CMS Petkus pool lines as seed parents and 6 Carsten-Danko lines as pollen parents. The respective 24 inter-pool crosses were evaluated for grain yield on several locations in 1996 and 1998.In EXP I GCA-variance of candidate lines (4.7 —5.9 q/ha2 was estimated to have a similar size as SCA-variance. Possible reasons for an overestimation of SCA-variance are extreme divergence between testers, insufficient removal of inbreeding effects in the intra-pool test crosses and bias due to SCA × year interaction-variance. The use of intra-pool testers should be restricted to breeding material where inbreeding due to consanguinity between testers and candidate lines is either absent or will evenly affect test cross performance of all candidates.In EXP II GCA-variances for female 9.2 q/ha2 and male 2.4 q/ha2 lines were much higher than SCA-variance. Repeatability for GCA-effects over different environments was medium (r=0.67), whereas for SCA-effects it was low (r=0.13). Selection intensity for yield should therefore be moderate, if based on a single year of testing only. Selection of parental components for hybrids and prediction of hybrid performance should mainly base on GCA-effects. Alternative to the use of factorial crosses test crosses with testers representing the opposite pool are recommended. Testing for SCA-effects and for SCA x environment interaction- effects can be a valuable diagnostic tool, to become aware of strengths and weaknesses of the elite material used to build new hybrids. SCA-tests should therefore be performed by using highly divergent environments

Screening and genetic studies on resistance to Soil-born Cereal Mosaic Virus (SBWMV) in rye

AbstractDue to several reasons soil-borne viruses such as the furoviruses, i. e., cereal mosaic virus (SBCMV) and wheat mosaic virus (SBWMV) as well as the bymovirus wheat spindle streak mosaic virus (WSSMV) gained importance in cereal breeding including rye. High yield losses are recorded, today. Since there is no or little resistance to these viruses in modern rye cultivars, an extended screening for resistance was initiated. In addition to earlier screenings, 37 rye genotypes were tested for resistance. Among them, three genotypes were found with persistent resistance to SBCMV. They belong to Secale montanum and S. vavilovii species, i. e., wild types of rye. One accession, PC2243 (S. montanum), was used as a resistance donor for the present genetic study. In F2 generation, it was observed that resistance to SBCMV is independently inherited from WSSMV. The evaluation of the ELISA values pointed to a 3:1 distribution assuming duplicate dominant epistasis. Molecular marker analysis supports this segregation pattern. By composite interval mapping a QTL on chromosome 2R could be detected. It can be assumed that there is a DNA region of about 13 cM on the long arm of chromosome 2R (2RL) harboring SBCMV resistance with the closest markers “C9654_1947” and “isotig11640”. Moreover, genotypes with a yellow seed coat showed practically no infection with SBCMV. Thus, the resistance gene could be linked to the allele an1 determining non expression of anthocyanins. This locus was also mapped earlier on chromosome 2R.</jats:p

Screening and genetic studies on resistance to Soil-born Cereal Mosaic Virus (SBWMV) in rye

Due to several reasons soil-borne viruses such as the furoviruses, i. e., cereal mosaic virus (SBCMV) and wheat mosaic virus (SBWMV) as well as the bymovirus wheat spindle streak mosaic virus (WSSMV) gained importance in cereal breeding including rye. High yield losses are recorded, today. Since there is no or little resistance to these viruses in modern rye cultivars, an extended screening for resistance was initiated. In addition to earlier screenings, 37 rye genotypes were tested for resistance. Among them, three genotypes were found with persistent resistance to SBCMV. They belong to Secale montanum and S. vavilovii species, i. e., wild types of rye. One accession, PC2243 (S. montanum), was used as a resistance donor for the present genetic study. In F2 generation, it was observed that resistance to SBCMV is independently inherited from WSSMV. The evaluation of the ELISA values pointed to a 3:1 distribution assuming duplicate dominant epistasis. Molecular marker analysis supports this segregation pattern. By composite interval mapping a QTL on chromosome 2R could be detected. It can be assumed that there is a DNA region of about 13 cM on the long arm of chromosome 2R (2RL) harboring SBCMV resistance with the closest markers “C9654_1947” and “isotig11640”. Moreover, genotypes with a yellow seed coat showed practically no infection with SBCMV. Thus, the resistance gene could be linked to the allele an1 determining non expression of anthocyanins. This locus was also mapped earlier on chromosome 2R