Project Lead(s): Kashif Riaz
Many bacterial pathogens can be controlled through pesticides. However, pesticides have significant economic and health-related costs, and pose a risk to biodiversity, biosafety and the environment. In Pakistan, particularly in Punjab, farmers have small farm holdings and bacterial diseases have been the major constraint to production.
Bacterial infections can be controlled through quorum quenching (QQ) – the capacity of bacteria to monitor their population density and regulate gene expression accordingly – which interferes with quorum sensing (QS), whereby bacteria coordinate gene expression according to the density of their local population.
The project team developed a product named "Quenchobac" – comprising QQ bacteria, a carrier and bio stimulants – for cost-effective, ecologically safe and sustainable bacterial disease management in vegetables.
The strategy involved harvesting QQ bacteria from the rhizosphere of potatoes, tomatoes and chilies, using simple culture enrichment procedures in which candidate bacteria are passed through several rounds of enrichment using QS and other indicator signaling molecules (NAHLs, 3-OH PAME and DSF).
The QQ ability of these bacteria was evaluated with the help of biosensors (CV026 and A. tumefaciens NTLR4). The candidate bacteria were then tested for their ability to control corresponding bacterial diseases caused by Pectobacterium, Ralstonia and Xanthomonas.
Successful candidates were identified using molecular tools (DNA sequence analysis of 16s rDNA) and retained for further studies.
Several natural products (such as plant extracts, peat, press mud, sugarcane bagasse and biochar) were evaluated for their ability to stimulate, retain, deliver and enrich QQ bacteria in the rhizosphere of potatoes, tomatoes and chilies.
These were tested in different proportions on healthy and diseased plants, to evaluate their effectiveness in controlling bacterial infections. A bioproduct (comprising bacterial consortia of several QQ strains) and selected biostimulant/carriers were mixed in different proportions/combinations, and were tested in the greenhouse and under field conditions at demonstration plots in the selected districts.
An ecologically safe, biodegradable, antibiotic/pesticide free and sustainable method of controlling bacterial diseases using a QQ approach that relies upon disarming rather than killing the bacterial pathogens has been developed and is now available.
The product, which is available from the plant pathology department at the University of Agriculture Faisalabad, controls diseases (47%–64% control of soft rot and wilt diseases of potatoes, tomatoes and chilies), enhances plant vigour by 31%–36%, increases yield by 15%–18% and decreases pesticide use by up to 28%.
The product does not contain any synthetic antibiotics or pesticides, and so does not lead to multi-drug resistance, residual toxicity or persistence in the environment.
As a result of the study, 168 people were engaged in this activity, including 120 labourers equally selected from three districts.