Some bacteria can feed on fungi, a phenomenon known as mycophagy. Here we show that a prophage tail-like protein (Bg_9562) is essential for mycophagy in Burkholderia gladioli strain NGJ1. The purified protein causes hyphal disintegration and inhibits growth of several fungal species. Disruption of the Bg_9562 gene abolishes mycophagy. Bg_9562 is a potential effector secreted by a type III secretion system (T3SS) and is translocated into fungal mycelia during confrontation. Heterologous expression of Bg_9562 in another bacterial species, Ralstonia solanacearum, confers mycophagous ability in a T3SS-dependent manner. We propose that the ability to feed on fungi conferred by Bg_9562 may help the bacteria to survive in certain ecological niches. Furthermore, considering its broad-spectrum antifungal activity, the protein may be potentially useful in biotechnological applications to control fungal diseases.

The present study provides evidence of a unique function of RGG1 in providing salinity stress tolerance in transgenic rice without affecting yield. It also provides a good example for signal transduction from the external environment to inside for enhanced agricultural production that withstands the extreme climatic conditions and ensures food security. The role of heterotrimeric G-proteins functioning as signalling molecules has not been studied as extensively in plants as in animals. Recently, their importance in plant stress signalling has been emerging. In this study, the function of rice G-protein γ subunit (RGG1) in the promotion of salinity tolerance in rice (Oryza sativa L. cv. IR64) was investigated. The overexpression of RGG1 driven by the CaMV35S promoter in transgenic rice conferred high salinity tolerance even in the presence of 200 mM NaCl. Transcript levels of antioxidative genes, i.e., CAT, APX, and GR, and their enzyme activities increased in salinity-stressed transgenic rice plants suggesting a better antioxidant system to cope the oxidative-damages caused by salinity stress. The RGG1-induced signalling events that conferred tolerance to salinity was mediated by increased gene expression of the enzymes that scavenged reactive oxygen species. In salinity-stressed RGG1 transgenic lines, the transcript levels of RGG2, RGB, RGA, DEP1, and GS3 also increased in addition to RGG1. These observations suggest that most likely the stoichiometry of the G-protein complex was not disturbed under stress. Agronomic parameters, endogenous sugar content (glucose and fructose) and hormones (GA3, zeatin and IAA) were also higher in the transgenic plants compared with the wild-type plants. A BiFC assay confirmed the interaction of RGG1 with different stress-responsive proteins which play active roles in signalling and prevention of aggregation of proteins under stress-induced perturbation. The present study will help in understanding the G-protein-mediated stress tolerance in plants.

Tomato leaf curl virus (ToLCV) belonging to Begomovirus family of Geminivirus is known to cause one of the most destructive diseases in tomato. Amongst various ToLCVs, a monopartite Tomato leaf curl Joydebpur virus (ToLCJoV) is most prevalent in eastern part of India. In the present study, we observed induced expression of one of the negative regulators of ethylene signaling pathway gene (LeCTR1) in ToLCJoV infected plants. The Tobacco rattle virus (TRV) induced silencing of the LeCTR1 gene provided enhanced tolerance to ToLCJoV infections. The leaf curling as well as ROS accumulation was significantly reduced in the viral infected LeCTR1 silenced plants. Induction of several defense marker genes (NPR1, PR1, PR5, AOS2, EIN2, EIN3 and ERF5) reinforced enhanced tolerance against ToLCJoV infection in the LeCTR1 silenced tomato. Overall, the present study provides evidence that silencing of LeCTR1 can be deployed to protect tomato from ToLCJoV infections.

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Fungal pathogens are responsible for approximately two third of the infectious plant diseases. Historically they have been associated with several devastating famines, causing death and disabilities in humans. Mostly fungal diseases are being controlled by using fungicides which otherwise have adverse side effects on the health of consumers as well as environment. Due to extensive usages, pathogens have evolved resistance against most of the commonly used fungicides and rendered them ineffective. Controlling fungal disease in a sustainable and eco-friendly fashion remains a challenge. The antifungal biocontrol agents are being considered as potent, alternative and ecofriendly approach to manage fungal diseases. In our recent work, we have identified a rice associated bacterium; Burkholderia gladioli strain NGJ1 which demonstrates broad spectrum fungal eating (mycophagous) property. We determined that the bacterium utilizes its type III secretion system (Injectisome) machinery to deploy a prophage tail-like protein (Bg_9562) into fungal cells to devour them. The purified Bg_9562 protein from overexpressing recombinant E. coli strain demonstrates broad spectrum antifungal activity. Overall our study opens up a new opportunity to exploit prophage taillike protein as potent antifungal compound to control plant as well as animal fungal diseases.