GENETIC ANALYSIS OF ALKALOID ACCUMULATION IN SEEDS OF WHITE LUPIN (Lupinus albus L.)

In the white lupin (Lupinus albus L.), the approach to breed `sweet' cultivars with a reduced content of alkaloids in seeds and forage is challenging. The study was conducted to advance the limited knowledge on genetic causes controlling the accumulation/composition of alkaloids in seeds of the white lupin. Using a diallel cross design among the chosen 'sweet' and 'bitter' parents, all the range of genetic variation, inheritance mode, type of gene action, and combining abilities were examined among parents and their F1 and F2 progenies. Total alkaloid content and individual composition of alkaloids were evaluated by gas chromatography. In the study, a relatively complex mode of alkaloid inheritance was observed. For the proportion of some alkaloids (e.g. sparteine and ammodendrine), the simple additive-dominance model of analysis was less adequate suggesting an incidence of non-allelic interaction and dependent distribution of genes in parents. Both additive and non-additive gene effects were significant for most alkaloids, but the preponderance of gene dominance prevailed. Overdominance (mainly in F1) and partial or complete dominance (in F2) of genes was noticed for properties of most alkaloids. Directional dominance was evident and variable, depending on the examined alkaloids. Contribution of non-additive gene effects and the degree of dominance tended to decrease among F-2-progenies, suggesting a relatively rapid fixation of additivity in successive hybrid generations. However, selection for the content and composition of alkaloids should be more effective if the still lasting, masking non-additive gene causes would be eliminated in subsequent hybrid generations.