Supplementary file 1_Somatic genome doubling determines fertility in maize haploids of inbred A427.docx

Spontaneous haploid genome doubling (SHGD) offers a biological alternative, but its developmental dynamics and cellular basis remain unresolved. Here, using the high haploid male fertility (HMF) genotype A427, we integrate flow cytometry, stomatal phenotyping and whole-plant performance analyses across three independent experimental years involving 2,924 individual measurements to characterize the temporal progression of genome doubling.

Fertile and sterile A427 haploids showed progressively divergent nuclear DNA-content profiles during vegetative development, with fertile plants exhibiting increasing enrichment of 2C and 4C nuclear fractions at later leaf stages. Stomatal length at the 5th leaf stage (L5) strongly discriminated between plants subsequently classified as male fertile and male sterile (apparent AUC = 0.886), providing a proof-of-concept for early, non-destructive selection.