Altered regulation of defense responses in maize hybrids
A.I. Hudson, P. J. Balint-Kurti
Department of Entomology and Plant Pathology, North Carolina State University, Thomas Hall 2508, 112 Derieux Place, Raleigh, NC 27695, USA

Maize hybrids are often more vigorous and higher-yielding than their inbred parents. Plant-microbe interactions have been shown to affect the magnitude of hybrid vigor. To investigate whether this may be due to differences in defense responses, we investigated pattern triggered immunity in inbred and hybrid maize by measuring responses following inoculation with microbial elicitors. The strength of pattern triggered immunity in several hybrids of diverse inbred lines was dependent on both genotype and the time of day at which the assays were performed. At dawn, defense responses in hybrids were intermediate between their respective parents or slightly below the less responsive parent. During the day, defense responses decreased in both inbred and hybrid lines but to a greater extent in hybrids, such that they responded less than either inbred parent. The reduction of defense responses in hybrids during the day, when there may be a trade-off with photosynthesis, suggests that altered regulation of defense may contribute to hybrid vigor.