Rice Gene Network Inferred from Expression Profiling of Plants Carrying Xa3/Xa26.

Japonica rice (Oryza sativa ssp. japonica) variety Mudanjiang 8 (MDJ8) is the wild-type and is susceptible to Xoo. Transgenic rice line Rb49 carries the MR gene Xa3/Xa26, which is driven by its native promoter with the genetic background of MDJ8, and this line is resistant to certain strains (including strain PXO61) of Xoo. Although many studies on Xa3/Xa26-mediated resistace to rice Xoo have been published, the molecular mechanism of this major resistance gene remains poorly understood. Here, we use affymetrix microarray technology to analyze the regulated network mediated by Xa3/Xa26 We used microarrays to study the gene expression network mediated by Xa3/Xa26. Plants were inoculated with the Xoo strain PXO61 at the four-leaf to five-leaf stage by the leaf-clipping method. Control rice plants were inoculated with water (mock inoculation). Samples were collected before inoculation (ck) and at 2, 4, and 24 hours after PXO61 or mock inoculation from Rb49 and MDJ8. Leaf fragments approximately 2 cm in length that were immediately next to the inoculation site were collected. Rice leaves collected at different time points post mock or PXO61 treatments were selected for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain the regulated network mediated by Xa3/Xa26.