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Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most destructive bacterial disease of rice. The cloned rice gene Xa21 confers resistance to a broad spectrum of Xoo races. To identify genes involved in Xa21‐mediated immunity, a whole‐genome oligonucleotide microarray of rice was used to profile the expression of rice genes between incompatible interactions and mock treatments at 0, 4, 8, 24, 72 and 120 h post inoculation (hpi) or between incompatible and compatible interactions at 4 hpi, respectively. A total of 441 differentially expressed genes, designated as XDGs (Xa21 mediated differentially expressed genes), were identified. Based on their functional annotations, the XDGs were assigned to 14 categories, including defense‐related, signaling, transcriptional regulators. Most of the defense‐related genes belonged to the pathogenesis‐related gene family, which was induced dramatically at 72 and 120 hpi. Interestingly, most signaling and transcriptional regulator genes were downregulated at 4 and 8 hpi, suggesting that negative regulation of cellular signaling may play a role in the Xa21‐mediated defense response. Comparison of expression profiles between Xa21‐ and other R gene‐mediated defense systems revealed interesting common responses. Representative XDGs with supporting evidences were also discussed. [ABSTRACT FROM AUTHOR]

By using a whole-genome oligonucleotide microarray, designed based on known and predicted indica rice genes, we investigated transcriptome profiles in developing leavesand panicles of superhybrid rice LYP9 and its parental cultivars 93-11 and PA64s. We detected 22,266 expressed genes out of 36,926 total genes set collectively from 7 tissues, including leaves at seedling and tillering stages, flag leaves at booting, heading, flowering, and filling stages, and panicles at filling stage. Clustering results showed that the Fl hybrid's expression profiles resembled those of its parental lines more than that which lies between the 2 parental lines. Out of the total gene set, 7,078 genes are shared by all sampled tissues and 3,926 genes (10.6% of the total gene set) are differentially expressed genes (DG). As we divided DG into those between the parents (DGpp) and between the hybrid and its parents (DGHP), the comparative results showed that genes in the categories of energy metabolism and transport are enriched in DGHP rather than in DGpp. In addition, we correlated the concurrence of DG and yield-related quantitative trait loci, providing a potential group of heterosis-related genes. [ABSTRACT FROM AUTHOR]