Stylar canal architecture of maize is not an indicator of resistance to Fusarium verticillioides infection

Fusarium verticillioides causes Fusarium ear rot (FER) of maize and contaminates the grain with mycotoxins called fumonisins. Structural barriers that prevent infection include a closed stylar canal of kernels, which has been suggested to contribute to resistance to FER. In this study, the stylar canal architecture of nine maize inbred lines, characterised for their response to F. verticillioides , was evaluated using scanning electron microscopy. The stylar canal of ovaries, sampled at 1–2 weeks before pollination, and maturing kernels sampled at approximately 1 month after self-pollination, were evaluated. Three inbred lines, CML 390 (highly resistant), RO 544 W (intermediately resistant) and R2565y (susceptible), had ovaries predominantly with closed stylar canals, with 92, 95 and 64.3% of the canals viewed as closed, respectively. Other highly resistant (CML 444, VO 617Y-2 and US 2540 W), intermediately resistant (RO 549 W) and susceptible (R119W and I137tnW) inbred lines displayed a mostly open stylar canal prior to pollination. The stylar canals of all inbred lines were mostly closed 1 month after pollination (90.3–100%). No significant association was found between stylar canal architecture and the FER-resistance status of the maize lines evaluated for ovaries and maturing maize kernels ( P > 0.05). The results of the study suggest that the stylar canal architecture may facilitate fungal ingress but does not play a pivotal role in resistance to F. verticillioides .