Soybean resistance to stem-mining agromyzid beanflies (Diptera: Agromyzidae).
A total of 6775 accessions were evaluated for field resistance to Melanagromyza sojae, M. dolichostigma, Ophiomyia centrosematis and O. phaseoli. Four wild accessions were classed as highly resistant. Resistance seemed to be positively correlated with trichome density, production of secondary xylem and lignified xylem, and the existence of polyphenols in the stem. A malvidin-based purple colour in the epidermis of the stem of G. soja was found to indicate that the underlying tissues contain the aforementioned traits of resistance.