Indian agricultural scientists are set to release a vaccine that will boost the immune system of paddy (rice). This vaccine, to start with, will tackle the Xoo bacterium (Xanthomonas oryzaepv.oryzae), that causes bacterial leaf blight in paddy plants.

Paddy farmers suffer huge losses due to the Xoo infection across the world. In India, the bacterial leaf blight has led to an average yield loss of 22.5 per cent during wet seasons and 7.5 per cent in dry seasons, according to studies.

The crop loss depends on the spread of the disease and the problem is not confined to India alone.

About 440 million tonnes of rice is consumed globally, mainly in Asia and Africa. Losses due to such diseases push up production costs and thus affect millions of poor in Asia and Africa who consume the foodgrain.

A Press Information Bureau release said that a team led by Department of Science and Technology (DST) fellowship winner Dr Tayi Lavanya has found that treatment of paddy with cellulase resulted in an enzyme being secreted to resist the attack on the paddy cell wall by the bacteria and prevent subsequent attacks.

Lavanya and her team are engaged in fine-tuning their strategy at the Centre for Plant Molecular Biology (CPMB), Osmania University, in Hyderabad.

The group is developing new vaccines that can activate the paddy immune system, thus helping the plant overcome subsequent infection.

The CMBP team has carried out biochemical and functional studies on plant cell wall degrading enzymes that are secreted by Xoo. This has provided key insights into the mechanisms of how the Xoo pathogen interacts with rice plant and cause the disease.

Using leads she got from the work she did for her Ph. D, Lavanya, along with her group, has zeroed in on a few molecules derived from either the Xoo bacterium and from infected rice cell walls which they hope to develop into vaccines.

Currently, the group is working on a cellulase protein secreted by Xoo. This cellulase protein has the features of a vaccine as it triggers the immune system in the paddy plant. Pre-treatment of paddy plants with this protein could help them resist Xoo bacterium.

The team is also looking into other aspects of immunity and once identified, they would be also used to develop vaccine or protein to help the plants resist the harmful bacteria.

Till now, the resistance of the paddy plant was being strengthened with the introduction of genes known as “Resistance R” which involved manipulating the genes. This took a considerable amount of time and man-hours.

The resistance was only against some specific strains of the Xoo bacterium. The new strategy that Lavanya and her team are working will ensure broad resistance to the bacterial problem.