Homoeologous recombination is recurrent in the nascent synthetic allotetraploid Arachis ipaë nsis 3 Arachis correntina4x and its derivatives

Abstract

Genome instability in newly synthesized allotetraploids of peanut has breeding implications that have not been fully appreciated. Synthesis of wild species-derived neo-tetraploids offers the opportunity to broaden the gene pool of peanut; however, the dynamics among the newly merged genomes creates predictable and unpredictable variation. Selfed progenies from the neo-tetraploid Arachis ipaë nsis _ Arachis correntina (A. ipaë nsis _ A. correntina)4x and F1 hybrids and F2 progenies from crosses between A. hypogaea _ [A. ipaë nsis _ A. correntina]4x were genotyped by the Axiom Arachis 48K SNP array. Homoeologous recombination between the A. ipaë nsis and A. correntina derived subgenomes was observed in the S0 generation. Among the S1 progenies, these recombined segments segregated and new events of homoeologous recombination emerged. The genomic regions undergoing homoeologous recombination segregated mostly disomically in the F2 progenies from A. hypogaea _ [A. ipaë nsis _ A. correntina]4x crosses. New homoeologous recombination events also occurred in the F2 population, mostly found on chromosomes 03, 04, 05, and 06. From the breeding perspective, these phenomena offer both possibilities and perils; recombination between genomes increases genetic diversity, but genome instability could lead to instability of traits or even loss of viability within lineages.