A new study from UC Davis has revealed that drought causes lasting changes within the community of microbes that is found in and around the roots of rice plants. These root microbes are critical components of the plants that help them absorb nutrients from the soil.
The research may ultimately shed new light on how rice responds to dry spells, and how it can be engineered to withstand drought conditions.
As irrigated rice plants grow and develop, they go through a series of changes in the root microbiome based on the type of rice and its geographic location. Previous studies have shown that when a growing rice plant is lacking in water, the changes in the root microbiome stall out.
For the current investigation, the experts analyzed changes in root microbial communities as rice plants were deprived of water for 11, 21 or 33 days. This kind of intermittent drought condition is more common in rain-fed crops than terminal drought, explained study co-author Professor Venkatesan Sundaresan.
The researchers were not surprised to find that the microbes changed in drought conditions. However, they were surprised to find that the changes persisted for weeks after plants were watered again.
“Rice plants carry a ‘memory’ of the drought episode in their root microbiota, so that plants that have experienced drought can be distinguished solely on the basis of their microbiomes,” said Professor Sundaresan.
“The persistence of changes to the microbiome means that root elongation continues even after drought has ended. This allows the roots to be better prepared to tap deep water.”
Professor Sundaresan explained that for some drought tolerant rice strains – after a drought episode, the roots will continue to grow long enough to penetrate the hardpan.
The microbiome response will be more rapid the next time the rice plants encounter drought, because it has already been altered.
The study authors noted that crops are likely to experience frequent intermittent droughts as extreme climate events become more common. A better understanding of how the plants will respond could lead to strategies to reduce crop losses.
The study is published in the journal Nature Plants.