In an interesting discovery, a widespread virus that typically damages plants from the cabbage family, such as broccoli and carrots, is seen to benefit its guests in times of crisis.
During times of thirst, researchers have discovered that the mosaic virus can turn from an obstruction to an aid, altering the host’s circadian clock so that the plant loses less water.
In the study, when a species of wild herb, called cress thale (Arabidopsis thaliana), infected with a specific variant of the virus, researchers found that the plant was 25 percent more likely to survive water stress afterwards.
And it seems to be hitting the weather.
“Under normal conditions, the virus shows its classical appearance as a pathogen by killing plants with water,” says the sociologist Santiago Elena Fito, chair of the Institute for Integrated Systems Biology (I2SysBio) explaining.
“However, the infectious plants that were under stress conditions as a result of thirst, survived.”
Cress Thale. (Marie-Lan Nguyen / Wikimedia Commons / CC-BY 2.5)
To find out what caused these changes, researchers treated healthy plants with mutations of the virus that had either grown under thirst-like conditions or had grown up below normal water levels. .
The irrigated plants would then be watered normally or under water shortage.
These variants of the virus that developed under normal conditions were still causing infection in these plants. But those variables that came out under thirst-like conditions showed more mercy, even when the hosts were still getting good water.
The results show that thirst-borne viruses somehow cause changes in the gene’s gene transcription to help them live better. In fact, the authors found that plants infected with these variables showed genetic changes linked to their circadian clock, which affects plant water use.
In a rapidly warming world, where more frequent and intense thirst threatens the future of many crops, that experience could be a lifesaver.
Previous research has shown that some viruses can cause disease in arable plants but they do not appear to affect wild plants in the same way. Scientists believe this is because host virus relationships fall on a spectrum from pathogenesis (or disease) to homogenization (where everyone benefits). And some environmental conditions can help shape where a virus falls on that line.
In 2008, researchers detected a number of mosaic viruses that appeared to improve plant tolerance to environmental stress, strengthening their antioxidants and water protection.
In 2013, another study showed that combined thirst and heat could alter the signaling pathways of turnip mosaic virus, although this was thought to reduce the plant’s heat response and not improve it.
The authors state that their study is the first to show that environmental conditions can directly affect a viral relationship with its host, progressing from pathogenesis to homogenization in a single life cycle. .
“It has been previously observed that viruses can make their host thirsty,” the authors write, “but, to our knowledge, this is the first time that it has been studied as such. mature strains shape the evolution of host virus interactions. ”
When opposed to a non-biological threat, the study suggests that some plants can alter their metabolism and gene expression, triggering changes that affect viral infectious production.
Viruses that grow in plants under these thirst-like conditions have largely learned not to kick the host while they are down.
“Our data suggest that virus modification under thirsty conditions leads to a different variation of transcription in their local hosts,” the authors write.
“A comparison of the gene expression in plants infected with normal viruses and thirsty evolution showed that most of the different definitions occur in a thirsty environment,” they add.
In other words, this type of viral infection can alter the thirst tolerance of tallow plants, promote host survival and ensure the survival of the virus itself. This is ultimately what allows the disease to reproduce and spread even under stressful conditions.
The method used by viruses to induce thirst tolerance in plants does not seem to be universal, the authors say, and it seems to be different even within species. But if we can figure out how to turn these common diseases from pathogens to partners, it could help us prepare our crops for the dry spells ahead.
The study was published in PNAS.