Going Inside the Rice Microbiome
When Harsh Bais grows rice plants in trays of water in his greenhouse at the University of Delaware, he can easily spot the ones that have been exposed to arsenic: They are stunted, with shorter stems and shrunken, yellow-tinged leaves.
Dr. Bais is working to develop rice plants that take up less arsenic, a common contaminant in the fields of his native India and other Asian countries. Chronic exposure to arsenic has been linked to heart disease, diabetes and genetic damage associated with elevated risk for cancer.
But instead of trying to breed new strains of rice or alter its DNA, he and other scientists have set out in a surprising new direction. They are looking at the vast and untapped microbial community that lives near the rice’s roots.
These bacteria are the botanic equivalent of the human microbiome — the trillions of organisms that live in our guts, many performing beneficial tasks like digesting food and fighting off infection.
The hope is to find bacteria that will somehow block arsenic in its path from soil to roots to stem to edible grain. In the past three years, Dr. Bais has isolated about a dozen bacterial species, added them to plants in the greenhouse and looked for the telltale signs of arsenic poisoning.
Now, he says, he has zeroed in on one species, Pantoea agglomerans, that seems to reduce arsenic in the plant’s stem to one-eighth its former levels.
“Research on the plant microbiome is very hot because everyone is trying to find things that can increase growth and yield,” said Dr. Bais, an associate professor of plant and soil sciences at Delaware. But he added that for him, arsenic in rice was a “burning issue.”