The characteristics of inheritance signs in Arabidopsis root system at interaction genes ETR1 and ETR2 are studied. It is stated, that at crossing plants of mutant lines Etr1-1 х Etr2-1 polymeric interaction of genes ETR 1 and ETR2 takes place. In that case splitting in F2 occurs in ratio 9:6:1. In hybrids of first generation the somatic heterosis is observed, that becomes apparent in more vigorous development of side roots in comparison with primary forms. In F1 on genes ETR1 and ETR2 in each alleles pair the domination of mutant gene over wild type gene (ETR1<Etr1-1 ETR2<Etr2-1) occurs. In hybrid plants of first generation the additive effect of non-alleles, dominating mutant genes Etr1-1 и Etr2-1 is observed. In the second generation the process of splitting hybrids is going on, their superiority over parental forms as to the length of side roots decreases. It has to do with shortening heterozygosity of plants in the generation F2.