Inheritance of erucic acid in brassica carinata a braun and development of low glucosinolate lines
Ethiopian mustard (Brassica carinata A. Braun) or gomenzer is an oilseed crop that is well adapted to the highlands of Ethiopia. Evaluation of the local germplasm has resulted in the registration of high yielding cultivars, such as Dodolla and S-67. The oil of gomenzer contains about 40% erucic acid and the meal is high in glucosinolates. The objective of this research was to study the inheritance of erucic acid content in gomenzer and to introgress genes for the non2-propenyl glucosinolate trait from B. napus and B. juncea. The erucic acid content of F1 seed from reciprocal crosses between the high erucic acid cultivars Dodolla and S-67 and zero erucic acid line C90-14 was intermediate between the parents indicating that erucic acid content in B. carinata was controlled by two nondominant genes with two alleles acting in an additive manner. Backcross F1 seed derived from the backcross to the low erucic acid parent fell into three erucic acid classes with $$16% erucic acid at the ratio of 1:2:1 indicating that erucic acid was under the control of two alleles each of at two loci. F2 seed segregation data supported this observation. Each allele contributed approximately 10% erucic acid. The high glucosinolate B. carinata line C90-14, low glucosinolate B. napus cultivar Westar and B. juncea line J90-4253 were chosen as parents for the development of non2-propenyl glucosinolate B. carinata. The objective was to transfer genes for non2-propenyl glucosinolate content from B. napus and B. juncea into B. carinata. Interspecific crosses were made between B. carinata and B. napus, B. carinata and B. juncea and the interspecific F1 generations were backcrossed to B. carinata. Backcross F1 plants from the two interspecific crosses were intercrossed in an attempt to combine the two sources for non2-propenyl glucosinolate content in one genotype. Seed of backcross F1 plants of the cropss ((B. carinata x B. napus) x B. carinata) contained a high concentration of 2-propenyl glucosinolate similar to those of B. carinata. Introgression of C genome chromosomes of B. napus into B. carinata was not effective in redirecting glucosinolate synthesis away from 2-propenyl and into 3-butenyl glucosinolate. This indicated that C genome chromosomes do not contain genetic factors for C3 $\to$ C4 glucosinolate precursor chain elongation, and that 2-propenyl glucosinolate synthesis is primarily controlled by genes on B genome chromosomes. Seed of ackcross F2 plants of the cross ((B. carinata x B. juncea) x B. carinata) contained much reduced levels of 2-propenyl glucosinolate indicating that genetic factors for C3 $\to$ C4 glucosinolate precursor chain elongation were introgressed from the B genome of B. juncea into the B genome of B. carinata. However, a complete diversion of glucosinolate synthesis from 2-propenyl to 3-butenyl was not achieved. Further selections in segregating F4 and F5 generations of B. juncea derived B. carinata populations could yield the desired zero 2-propenyl glucosinolate B. carinata. The double interspecific cross was unsuccessful.
DegreeDoctor of Philosophy (Ph.D.)
Copyright DateApril 1996