Low-iron conditions induces the hypersensitive reaction and pathogenicityhrpgenes expression inXanthomonasand is involved in modulation of hypersensitive response and virulence

Abstract

Expression of hrp (hypersensitive reaction and pathogenicity) genes inside the host is crucial for virulence of phytopathogenic bacteria. The hrp genes encode components of type3 secretion system (T3SS), HR elicitors and several regulators, which are involved in the co-ordinated expression of hrp genes in the host environment and in hrp inducing chemically defined medium. However, little is known about specific host or environmental factors which may play a role in the induction of hrp gene expression. In this study, we show that iron-limiting condition elicits induced expression of hrp genes, including type3 secretion system (T3SS) and effectors (T3E). Expression analysis using qRT-PCR and promoter probe strains suggest significant induction in the expression of Hrp and T3S-associated genes of Xanthomonas campestris pv. campestris (Xcc) under low-iron condition, and is suppressed by exogenous supplementation of iron. Furthermore, we show that with exogenous iron supplementation, wild type Xcc exhibited reduced disease symptoms in host-plant, and exhibited significant reduction in HR and callose deposition in the non-host plants. Xanthomonas oryzae and oryzicola pathovars also exhibited the iron affect, albeit to a lesser extend compared with the Xcc. Overall, our results suggest that low-iron condition inside the host may play a crucial role in pathogenicity.

Novel Benzothiazole Derivatives as Potential Anti-Quorum Sensing Agents for Managing Plant Bacterial Diseases: Synthesis, Antibacterial Activity Assessment, and SAR Study

“…We therefore examined whether compound D 3 inhibits the expression of other virulence factors, such as the type III secretion system (T3SS). Some studies have suggested that components of the T3SS are encoded by hrp family genes, which induces hypersensitivity reactions in the host. , Various effector proteins can be injected into host plant tissues by the T3SS . To evaluate the effect of compound D 3 on the HR, we performed HR assays using nonhost Nicotiana benthamiana leaves and water soaking assays using natural host 2-week-old rice seedlings.…”

“…34,37 Various effector proteins can be injected into host plant tissues by the T3SS. 47 To evaluate the effect of compound D 3 on the HR, we performed HR assays using nonhost Nicotiana benthamiana leaves and water soaking assays using natural host 2-week-old rice seedlings. Interestingly, the characteristic HR symptoms were effectively alleviated after pretreatment of Xoo with compound D 3 (Figure 8A).…”

Genomic Characterization Provides an Insight into the Pathogenicity of the Poplar Canker Bacterium Lonsdalea populi

“…Three secretory systems, T3SS, T4SS, and T6SS, were distributed in the N-5-1 genome. The hrp gene cluster regulates the invasion of pathogenic bacteria in host plants and the hypersensitive necrosis of non-host plants [43]. We identified 15 hrp genes in the N-5-1 strains.…”