Sugar availability influences sex determination in the root-knot nematode, Meloidogyne incognita, via changes in giant cell development

Summary Sex determination mechanisms in nematodes, including their responses to environmental cues, are pivotal for understanding their adaptability and ecological success. This study employs Arabidopsis thaliana as a model host to investigate how various stressors, particularly nutrient availability, influence sex ratios in the root-knot nematode Meloidogyne incognita . A significantly higher proportion of males was observed under sugar-limiting conditions, notably in sucrose-deficient media and at elevated nematode inoculation densities. Genetic analyses using mutants impaired in sugar transport and metabolism ( adg1-1 / tpt-2 , rbohD , stp12 ) also demonstrated a marked increase in male proportions, underscoring the critical role of sugar transport and availability in sex determination. Examination of giant cells – specialised feeding structures formed by the nematode – revealed a strong correlation between reduced cell size and male development, indicating that limited nutritional resources favour male differentiation. These findings enhance our understanding of the environmental factors governing sex determination in M. incognita .