Toward the development of a cross-compatibility framework to enhance the utilization of peanut CWRs

Utilizing valuable genes and alleles from crop wild relatives (CWRs) and transferring them to elite varieties requires a thorough understanding of species cross compatibility and reproductive systems. In this review, we examine interspecific crossing among peanut CWRs, chromosome pairing during meiosis, and pollen viability of Filial 1 hybrids. We analyze each parameter in relation to phylogenetic distances and current taxonomic and genomic classification, aiming to develop a cross-compatibility scheme for the crop's secondary gene pool. Analysis of passport information and species names from research groups worldwide over the past 60 years revealed diverse frequencies of genome combinations (17) and species (26) used in hybridization assays. However, only eight species accounted for nearly 50% of successful hybridizations. In intragenomic hybrids, bivalent frequency ranged from 9.1 to 10, with pollen viability typically between 30% and 60%. Intergenomic hybrids exhibited bivalent frequency between 4.8 and 8.5, with pollen viability below 10%. Outliers were observed in the various parameters and hybrids were analyzed. Phylogenetic distance presented an inverse relationship with all variables; the correlation was low with crossing success while moderate with bivalent frequency and pollen viability. These findings suggest that differences in DNA sequences are not the sole determinants of interspecific cross-compatibility, indicating the presence of pre- or postzygotic hybridization barriers. This organized information is crucial for establishing a framework to facilitate the rational selection of parents with desired traits and appropriate genome combinations, ultimately aiding in the development of new amphidiploids compatible with peanut varieties.