Innate immune responses are induced in plants and animals through perception of Damage Associated Molecular Patterns. These immune responses are suppressed by pathogens during infection. A number of studies have focussed on identifying functions of plant pathogenic bacteria that are involved in suppression of Pathogen Associated Molecular Pattern induced immune responses. In comparison, there is very little information on functions used by plant pathogens to suppress Damage Associated Molecular Pattern induced immune responses. Xanthomonas oryzae pv. oryzae , a gram negative bacterial pathogen of rice, secretes hydrolytic enzymes such as LipA (Lipase/Esterase) that damage rice cell walls and induce innate immune responses. Here, we show that Agrobacterium mediated transient transfer of the gene for XopN, a X . oryzae pv. oryzae type 3 secretion (T3S) system effector, results in suppression of rice innate immune responses induced by LipA. A xopN - mutant of X . oryzae pv. oryzae retains the ability to suppress these innate immune responses indicating the presence of other functionally redundant proteins. In transient transfer assays, we have assessed the ability of 15 other X . oryzae pv. oryzae T3S secreted effectors to suppress rice innate immune responses. Amongst these proteins, XopQ, XopX and XopZ are suppressors of LipA induced innate immune responses. A mutation in any one of the xopN, xopQ, xopX or xopZ genes causes partial virulence deficiency while a xopN - xopX - double mutant exhibits a greater virulence deficiency. A xopN - xopQ - xopX - xopZ - quadruple mutant of X . oryzae pv. oryzae induces callose deposition, an innate immune response, similar to a X . oryzae pv. oryzae T3S- mutant in rice leaves. Overall, these results indicate that multiple T3S secreted proteins of X . oryzae pv. oryzae can suppress cell wall damage induced rice innate immune responses.

ac and dc conductivities of fast-ion conducting xNa2S+(1-x)B2S3 glasses in the composition range 0.001≤x≤0.1 were analyzed using the Almond-West formula σ(ν)=σdc[1+(ν/νH)α]. The hopping frequency for free charge carriers νH, the dc conductivity σdc, and their respective activation energies were determined. The concentration of free charge carriers evaluated from the conductivities and estimated mobilities is in good agreement with the overall content of sodium cations in the glasses and it is proposed that this supports the concept of a strong and not weak electrolyte model for these fast-ion conducting glasses. Disciplines

A future challenge will be understanding the extensive communication that most likely takes place in bacterial interspecies and interkingdom signaling between plants and bacteria. A major bacterial inter-cellular signaling system in Gram-negative bacteria is LuxI/R quorum sensing (QS) based on the production (via the LuxI-family proteins) and detection (via the LuxR-family proteins) of N-acyl homoserine lactones (AHLs) signaling molecules. LuxR proteins which have the same modular structure of QS LuxRs but are devoid of a cognate LuxI AHL synthase are called solos. LuxR solos have been shown to be responsible to respond to exogenous AHLs produced by neighboring cells as well endogenously produced AHLs. It is now also evident that some LuxR proteins have evolved from the ability to binding AHLs and respond to other molecules/signals. For example, recent research has shown that a sub-family of LuxR solos responds to small molecules produced by plants. This indicates the presence of a uni-directional interkingdom signaling system occurring from plants to bacteria. In addition LuxR solos have now been also implicated to respond to endogenously produced signals which are not AHLs. In this Mini Review article we will discuss current trends and implications of the role of LuxR solos in bacterial responses to other signals using proteins related to AHL QS systems.