Construction of a core germplasm bank of upland cotton (Gossypium hirsutum L.) based on phenotype, genotype and favorable alleles

Core germplasm banks are constructed to provide breeders with maximum genetic diversity concomitant with minimum genetic redundancy for a faster breeding process with the least number of accessions possible. In this study, we collected a cotton germplasm collection including 477 cotton varieties cultivated in China and 26 introduced from America and the Soviet Union. Three primary germplasm banks (A, B, and C) were constructed based on phenotype, genotype, and favorable alleles, respectively. Accessions common to all three banks were selected to construct a core germplasm bank to faithfully represent the original genetic collection. The resulting core germplasm bank consisted of 85 accessions, accounting for 16.90% of the original germplasm resources. Construction of this core bank was followed by its evaluation based on phenotype, genotype, and favorable alleles. Compared with those of the original germplasm bank, the phenotype ranges of the core germplasm bank decreased slightly, whereas the coefficients of variation increased slightly. Average polymorphism information content and heterozygosity were estimated at 0.166 and 0.232, respectively, accounting for 80.19% and 87.22% of the corresponding values in the original germplasm bank. Additionally, the average number of favorable alleles polymerized in each accession was approximately 54, ranging from 45 to 64. Overall, the core germplasm bank obtained is characterized by great diversity and solid genetic representation; furthermore, it has a high number of favorable alleles. Thus, our study laid the groundwork for cotton germplasm resource collection and preservation, and cotton research and breeding.

Automated summary

This study constructed a core germplasm bank for cotton breeding, which consisted of 85 accessions representing 16.90% of the original germplasm resources. The core bank showed slightly decreased phenotype ranges and increased coefficients of variation compared to the original bank. It also exhibited high levels of genetic diversity, with an average polymorphism information content of 0.166 and heterozygosity of 0.232, accounting for a significant portion of the values in the original bank.