Zea mays subsp. mays Transcriptome or Gene expression. Zea mays subsp. mays

Sporisorium reilianum f. sp. zeae is an important biotrophic pathogen that causes head smut disease in maize. Head smut is not obvious until the tassels and ears emerge. S. reilianum has a very long life cycle that spans almost the entire developmental program of maize after the pathogen successfully invades the root. The aim of this study was to understand at a molecular level how this pathogen interacts with the host during its long life cycle, and how this interaction differs between susceptible and resistant varieties of maize after hyphal invasion. We investigated transcriptional changes in the resistant maize line Mo17 at four developmental stages using a maize 70mer-oligonucleotide microarray. We found that there was a lengthy compatible relationship between the pathogen and host until the early 8th-leaf stage. The resistance in Mo17 relied on the assignment of auxins and regulation of flavonoids in the early floral primordium during the early floral transition stage. We propose a model describing the putative mechanism of head smut resistance in Mo17 during floral transition. In the model, the synergistic regulations among auxins, flavonoids, and hyphal growth play a key role in maintaining compatibility with S. reilianum in the resistant maize line Overall design: After inoculation using the hyphae of S. reilianum, the shoot apexes of inoculated Mo17 (resistant maize line) that contained hyphae but displayed normal morphology were collected for RNA extraction at at four vegetative stages; the 2nd-, 4th-, 6th-, and 8th-leaf stages. RNA samples from mock-inoculated and inocultated Mo17 were hybridized to the 46K maize 70-mer oligonucleotide microarray. Hybridization was performed in three biological replicates with Cy5/Cy3 dye swap as technical replicates.