(see Figure 6). Eight this website of the 10 terms have their own child and lower level offspring terms, and each of those “”response”" terms has a child term such as “”maintenance of symbiont tolerance to host …”" (see details in Figure 6). The term “”GO ID 0075147 regulation of signal selleckchem transduction in response to host”" has five children to describe different types of signal transduction, similar to the five child terms of “”GO ID 0052470 modulation by host of symbiont signal transduction pathway”" in the first set. Each of the five terms has child terms for positive regulation and negative regulation. The three sets of new GO terms can be used

to explicitly describe genes of signal transduction pathways involved in host recognition. For instance, the PMK1 gene of the rice blast fungus Magnaporthe oryzae encodes a mitogen-activated protein kinase (MAPK), which is a key component in the MAPK signaling cascade and is involved in appressorium formation and infectious growth [32]. Thus, the PMK1 protein can be annotated with the term “”GO ID 0075171 regulation of MAP kinase-mediated signal

transduction in response to host”". Note that this gene product would not be annotated with “”GO ID 0052435 modulation by host of symbiont MAP kinase-mediated signal transduction selleck kinase inhibitor pathway”" since this latter GO term is reserved to annotate host gene products. Similarly, this protein should not be annotated with “”GO ID 0052080 modulation by symbiont of host MAP kinase-mediated signal transduction pathway”" since PMK1 belongs to the symbiont’s and not the host’s signaling transduction pathway. In addition, the modulation terms have children

that describe more specific kinds of signal transduction. For example, “”GO ID 0075168 regulation of protein kinase-mediated signal transduction in response to host”" has a child “”GO ID 0075171 regulation of MAP kinase-mediated signal transduction in response to host”" (see details in Figure 6). Penetration into the host Pathogens have evolved several mechanisms that include structural and/or enzymatic components in order to enter into their plant hosts [5]. Many fungi, such many as Alternaria alternata, Colletotrichum graminicola, M. oryzae, Pyrenophora teres, and many oomycetes, such as P. infestans and Phytophthora cinnamomi, develop appressoria to directly penetrate plant cuticles [13, 33–38]. An appressorium is a highly specialized structure that differentiates from the end of a symbiont germ tube. It is a swollen, dome-shaped or cylindrical organ, from which a narrow penetration peg emerges to rupture the plant cuticle and cell wall [33]. The penetration peg extends and forms a penetration hypha to penetrate through the epidermal cells and emerge into the underlying tissue [34, 35]. In some instances, penetration is driven by astoundingly high turgor pressures within the appressoria [36, 38].