CHANGES IN A SET OF GENES INFLUENCING QUA NTITATIVE TRAITS IN ARABIDOPSIS GROWN UNDER DIFFERENT CONDITIONS

Three experiments were performed in different years to study a pleiotr opic effect of two marker genes A and B on quantitative traits in Arab idopsis thaliana L. (Heynh.) Experiments differed in their conditions for plant growth (light intensity and soil fertility). In experiment 1 , substitution of B-by bb did not affect the duration of the sowing-fl owering period, whereas substitution or A-by aa caused a 2-day delay i n flowering. Experiment 2 showed that both genes affected this trait, The delay in flowering was one, two, or three days when B- was substit uted by bb, A- by aa, or A-B- by aabb, respectively, Therefore, these genes were additive. Data of experiments 3 were opposite to those of e xperiment 1: substitution of A- by aa did not affect the trait studied , whereas substitution of B-by bb caused st 2-day elongation of the so wing-flowering period, Thus, variations in growth conditions transform ed the effects of the marker genes duration of the sowing-flowering pe riod and changed a set of genes that determined this trait, Note that effects of A and B genes on other qualitative and quantitative traits (for example, plant height) were constant in all experiments, Therefor e, transformation of a gene set, which influenced the sowing-flowering period, was not related to the repression or derepression of A and B genes.