How defense genes originated with the evolution of their specific pathogen-responsive traits remains an important problem. and evolutionary processes of a gene recruited rapidly. Introduction To resist pathogen attacks, plants have evolved an efficient defense response system to elude or minimize the effects Goserelin Acetate of diseases. Many genes are involved in this defense system. The major disease resistance (genes and defense-responsive genes encoding similar proteins have been identified as involved in plantCpathogen interactions in both 22457-89-2 IC50 dicots and monocots. The accumulated evidence, however, suggests that the defense responses to pathogen infection are not 22457-89-2 IC50 necessarily the same in dicots and monocots. For example, a rise in the level of endogenous salicylic acid (SA) is required for systemic acquired resistance in dicots, but rice (L.), a model monocot, maintains a high level of SA without activating defense responses [4]. Activation of indole-3-acetic acid-amido synthetase can enhance disease resistance in both (a model dicot) and rice, but the former is associated with an increase in SA and the latter is SA independent [5], [6]. Identification of species-specific genes will help to elucidate the differences in pathogen-induced defense responses among plant species. A species-specific gene is the one that recently evolved or in rare cases the one that originated in the remote past but was lost in all other related species. A new gene evolved a new and species-specific disease resistance trait. A number of mechanisms that can generate new genes are known [7]. These mechanisms are often dependent on the duplication of ancestral genes or ancestral genomic sequences. Thus, the 22457-89-2 IC50 genes that originated from these mechanisms would have additional homologous gene copies in the same species or different species. However, recent studies in detected certain genes that have no homologs even in the species that diverged very recently [8]C[12]. This raised the possibility of a origination of new genes, to suggest the possibility that they may derive from ancestrally noncoding sequences or other unknown mechanisms [8], [10], although there is much to do in understanding the biology of these genes. It was speculated that many so-called 22457-89-2 IC50 orphan genes might actually be genes [13]; http://blogs.nature.com/nature/journalclub/2007/10. The evolution of genes is considered an important 22457-89-2 IC50 process in the genomes of some prokaryotes. Approximately 12% of genes in some archeal and proteobacterial species are thought to have origination based on a computational analysis [14]; however, the origin of these genes is unknown. Levine et al. [8] first reported origination of whole genes from expressed noncoding regions in and genes from noncoding regions were then discovered in and [9], [10] as well as in [12]. In comparison, the gene in was suggested to have evolved from a DNA sequence that inserted into its present site; repetitive sequences in this region may have contributed to structural and expression-level evolution of this gene [11]. Subsequently, we asked if plants have genes. If they do, we can use the well-developed biologic analyses to further investigate their biologic processes to reveal how a function can be generated by a gene. The defense system in rice is an excellent system to test this possibility because of the availability of rich analysis tools and knowledge about the disease resistance within the rice species. Bacterial blight of.