Timper, P., M. D. Krakowsky, and M. E. Snook. 2007. Resistance in maize to Paratrichodorus minor. Nematropica 37:9-20. The stubby-root nematode Paratrichodorus minor is widespread in the southeastern United States. Maize is both a good host for reproduction and sensitive to feeding damage from this nematode. The primary objective of this study was to evaluate commercial maize hybrids and public inbred lines for resistance to P. minor. A secondary objective was to determine whether there was a correlation between nematode reproduction and the concentration of benzoxazinones in maize roots. Thirty three commercial maize hybrids and 22 public inbred lines were evaluated for resistance to P. minor in the greenhouse. Pioneer hybrid 3223 served as a susceptible control. Pots containing sterilized loamy sand and one maize plant were inoculated with 500 mixed vermiform stages. Nematodes were extracted from the soil approximately 50 days after inoculation. Four hybrids (Croplan 822RR2/Bt, Southern States 842RR, Garst 8200YGI, and Pioneer 31G98) were moderately resistant to P. minor in three trials. Nematode reproduction on these four hybrids averaged less than 50% the reproduction on Pioneer 3223. None of the public inbred lines tested showed any resistance to P. minor relative to Pioneer 3223. The benzoxazinones present in the maize roots were the MBOA aglycone, and glucosides of DIM2BOA and DIMBOA. Concentrations of total benzoxazinones differed among maize hybrids; however, there was no relationship between concentrations and reproduction of P. minor. To better predict resistance to P. minor in maize hybrids, additional research is needed to identify inbred lines with resistance. Discovery of chemical or genetic markers for resistance would also be useful for screening inbred lines and hybrids.
