Scientists find method to help plants survive climate change

By Gwyn Wright via SWNS

A new way of helping plants survive in sweltering temperatures has been unearthed by scientists.

Researchers say a “master gene” which controls which genes are switched on and off in plants explains the discovery.

The team has found a way to make plants only switch on the “master gene”, called CBP60g, when they are under attack and not whenever it is hot.

If the findings hold up in crops, it could lead to a breakthrough that could help feed millions of people as the planet warms.

The discovery was made in a spindly plant with white flowers called Arabidopsis thaliana which is the “lab rat” of plant research.

It has long been known that higher temperatures make plants more vulnerable to pests by impairing their ability to create salicylic acid, a hormone that fires up their immune system.

Heat also causes tomatoes, rice and rapeseed to struggle to make the acid.

However, the molecular basis of this collapse in immunity was not well understood.

In the middle of the last decade, the researchers discovered that even short heat waves can dramatically reduce the amount of hormones they produce which can defend them against a nasty bacteria called Pseudomonas syringae.

Normally when it strikes, the amount of the acid in a plant’s leaves goes up sevenfold to stop bacteria from spreading.

However, when temperatures rise above 86 degrees Fahrenheit (30 degrees Celsius) plants can no longer make enough of it to stop infection from taking hold.

The study’s corresponding author Professor Sheng-Yang He said: “Plants get a lot more infections at warm temperatures because their level of basal immunity is down.

“We wanted to know, how do plants feel the heat? And can we actually fix it to make plants heat-resilient?”

Around the same time, a different team found out molecules in a type of plant cell called phytochromes function as internal thermometers.

These help plants sense warmer temperatures in the spring and activate growth and flowering.

The team wondered whether the same molecules were causing plants’ immune systems to wear out when it gets hot.

For the study, the researchers in the US and China compared normal plants and mutant plants whose internal thermometers are always active regardless of temperature.

They were infected with the nasty Pseudomonas syringae bug and grown at 23 degrees and 27 degrees Celsius (73 and 82 degrees Fahrenheit).

The mutants behaved exactly like normal plants and couldn’t make enough salicylic acid in high heat.

The researchers then spent years doing experiments with other mutant plants but found they also got sick in hot weather.

They then decided to use next-generation gene sequencing to compare plants in normal and hot temperatures.

Many of the genes that were suppressed at elevated temperatures turned out to be regulated by the same molecule, a gene called CBP60g.

This gene acts like a “master switch” that controls other genes- meaning anything that turns it off turns off other genes too, meaning plants can’t make proteins that allow them to build up salicylic acid.

Further experiments showed DNA, proteins and amino acids that are needed to start reading out genetic instructions in the CBP60g gene don’t assemble properly when it gets too hot, which is why the plant’s immune system can’t do its job anymore.

Mutant plants that had their CBP60g gene constantly “switched on” were able to keep their defense hormone levels up and bacteria at bay, even under heat stress.

They then found a way to engineer heat-resilient plants that only switched on the CBP60g “master gene” only when they are under attack, without stunting their growth.

Follow-up tests in rapeseed are showing similar results, the team say.

Professor He added: “We were able to make the whole plant immune system more robust at warm temperatures.

“If this is true for crop plants as well, that's a really big deal because then we have a very powerful weapon.”

Global warming is already making heat waves worse and weakening plants’ natural defenses.

Up to 40 percent of food crops worldwide are lost to pests and diseases each year, which costs the global economy $300 billion.

The world’s population is expected to reach 10 billion by 2050, and food production will need to increase by 60 percent to feed everyone on Earth.

The findings were published in the journal Nature.