A mutant with apetalous flowers in oilseed rape (Brassica napus): Mode of inheritance and influence on crop physiology and sclerotinia infection
Untersuchungen an einer bluetenblattlosen Mutante bei Raps (Brassica napus): Vererbungsweise und Einfluss auf Ertragsphysiologie und Krankheitsanfaelligkeit
von Lixi Jiang
Datum der mündl. Prüfung:2001-02-15
Erschienen:2001-02-23
Betreuer:Prof. Dr. Heiko C. Becker
Gutachter:Prof. Dr. Heiko C. Becker
Gutachter:Prof. Dr. Rolf Rauber
Zum Verlinken/Zitieren:
http://dx.doi.org/10.53846/goediss-1853
Dateien
Name:jiang.pdf
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Description:Dissertation
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Zusammenfassung
Englisch
Apetalous genotypes might be of interest in oilseed rape breeding because of their more efficient photosynthesis and reallocation of the photosynthesized assimilates and a lower probability of infection from pathogens distributed by petals. The mutant 'ap-Tengbe' with apetalous flowers and some breeding lines with complete or partial apetalous flowers were investigated for (1) the genetic regulation of apetalous flowers, (2) environmental effects, in particular the effect of some phytohormones, on expression of the petalous degree (PDgr), (3) the crop physiology, and (4) the infection from Sclerotinia disease. The German cultivar 'Falcon' was crossed with 'ap-Tengbe'. The F1, the two BC1 generations and their reciprocal forms, as well as the F2 were grown for observation of petalous degree (PDgr) in field experiments at Göttingen, Germany, 1998 and Hangzhou, China, 1999. The reciprocal F2 population was grown only at Hangzhou in 1999. The segregation of PDgr in various generations was recorded. The above materials were also observed for the changes of PDgr during flowering in the two environments. Moreover, in a field experiment at Göttingen 2000, double haploid (DH) lines with apetalous, partial apetalous and normal petalled flowers were treated with auxins and cytokinins and the effect of the hormones on the expression of PDgr was investigated. Crop physiology of an apetalous line with improved agronomic traits was compared with that of a partial apetalous and a normal petalled sister lines. Field experiments were grown at three plant densities and three nitrogen levels at two locations in northern Germany. Four apetalous lines, one partial apetalous and two normal petalled lines were field grown for the investigation of infected rate (IR) and severity index (SI) from Sclerotinia sclerotiorum disease by field scoring in Hangzhou China 1999. In addition, three other apetalous lines, their normal petalled sister lines and two German varieties were grown at two locations in northern Germany 2000. Some enzyme tests were compared for their efficiency in identifying the infection degree (ID) quantitatively. Stem samples were analyzed for infection degree (ID) from Sclerotinia disease by protease and xylanase tests. The results reveal that (1) the apetalous character in 'ap-Tengbe' is regulated by an interaction of cytoplasmic genes and two pairs of nuclear genes. Completely apetalous flowers are only expressed in genotypes with the 'ap' cytoplasm and two homozygous recessive genes (p1p1p2p2). (2) PDgr decreases from initial anthesis to end of flowering in materials with apetalous parent involved. The reduction of PDgr in these plants is caused by endogenic accumulation of auxins or/and cytokinins during flowering. (3) petals largely reduce the transmission of photosynthetic active radiation to the upper leaves. They have negative effects on leaf area index (LAI) and duration of active green leaves as well as on total biomass dry matter weight. They have, however, no negative effects on oil and protein content of seed. Yield advantage of apetalous genotypes differs for various genetic sources for this trait. Apetalous lines with 'ap-Tengbe' background had a disadvantage in grain yield probably due to less pollen production. (4) apetalous lines are less infected from Sclerotinia disease in comparison to their normal petalled sister lines. Analyses of protease and xylanase with appropriate concentrations of the exaction of infected plant tissues are efficient in determining infection degree from Sclerotinia disease quantitatively. In conclusion, the mutant 'ap-Tengbe' can be successfully used to develop completely apetalous breeding lines, but cytoplasmic effects have to be considered. Apetalous lines have a potential to increase grain yield and Sclerotinia resistance. For future breeding, 'ap-Tengbe' would be more valuable if the genetic linkage between apetalous flowers and low pollen production could be broken.
Keywords: apetalous flower; Brassica napus; mutagenesis; inheritance; cytoplasmic effect; crop physiology; Sclerotinia infection
