Fig. 1: There are five hypotheses to explain the mechanism of heterosis based on gene effects. | Horticulture Research

Fig. 1: There are five hypotheses to explain the mechanism of heterosis based on gene effects.

From: Molecular basis of heterosis and related breeding strategies reveal its importance in vegetable breeding

Fig. 1

Suppose that the biomass is the sum of the genetic effects (A, B, C) and that the biomass of an organism is represented by the circular area. A Dominance effect: the dominant allele (A) inhibits the recessive allele (a); (B) overdominance effect: a single heterozygous allele (B/B−) promotes the development of heterosis; (C) Epistasis effect: nonallelic (A1/B1) interactions in the parents promote the development of heterosis; (D) active gene effect: genes from parents (C) promote heterosis when heterozygous and produce genome imprinting when homozygous, which inhibits the occurrence of heterosis; (E) gene network system: genes from parents (A, B, C) are combined into a coordinated gene network system that enables F1 to develop heterosis; (F) single-cross hybrids P1 (AB) and P2 (CD) produced from four homozygous inbred tetraploids (with genotypes A, B, C, and D) are crossed to produce F1 (ABCD), a double-cross tetraploid hybrid

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