Inbreeding depression in diploid potato: genetic basis, deleterious load, and breeding mitigation

Area of Science:

• * Plant genetics and breeding
• * Molecular biology and genomics

Background:

• * Diploid hybrid potato development is crucial for modern breeding but hindered by inbreeding depression.
• * Long-term clonal propagation and polyploid buffering contribute to the accumulation of deleterious genetic load.
• * Increased homozygosity during selfing exposes recessive deleterious variants, impacting potato traits.

Purpose of the Study:

• * To systematically review the phenotypic characteristics and accumulation mechanisms of inbreeding depression in diploid potatoes.
• * To summarize quantitative evaluation systems for inbreeding depression and genetic load.
• * To discuss breeding interventions and future prospects for diploid potato inbred line development.

Main Methods:

• * Narrative review of existing literature on diploid potato breeding and inbreeding depression.
• * Analysis of mechanisms driving deleterious load accumulation through selfing and genetic buffering.
• * Compilation and discussion of quantitative evaluation systems and breeding strategies.

Main Results:

• * Inbreeding depression manifests as reduced plant vigor, reproductive capacity, tuber yield, tuber quality, and stress tolerance.
• * Continuous selfing increases genome-wide homozygosity, exposing recessive deleterious variants.
• * Various breeding strategies, including genomic prediction, marker-assisted selection, genome editing, and hybrid complementation, show potential but have limitations.

Conclusions:

• * A clear framework links deleterious load, homozygosity, phenotypic decline, and breeding strategies in diploid potatoes.
• * Genome design breeding offers prospects for purging deleterious variants.
• * Theoretical references are provided for advancing diploid potato inbred line breeding, distinguishing lab progress from industrial application.