How heat waves weaken plants (and thoughts on parallels in Humanity)

If one makes the questionable decision to look into the rhetoric and arguments of genocide deniers, one common refrain sounds a bit like, “It’s not a genocide, because a lot of them just died from starvation, disease, or exposure to the elements. The reality is that poor conditions are deliberately inflicted because we know that those conditions make people more vulnerable to disease, and less likely to fight back. I’m starting with this rather grim opening, because we’re entering an era in which the natural world is getting more dangerous not just for us, but for most other species on the planet. Basically, poor conditions are increasingly becoming the default, and that’s making everybody suffer.

Today’s example is plants. Plants are being made more vulnerable to disease by the changing climate. This is not new, and it’s not limited to plants. What is new, is this research into why that is:

Scientists have known for decades that above-normal temperatures suppress a plant’s ability to make a defense hormone called salicylic acid, which fires up the plant’s immune system and stops invaders before they cause too much damage. But the molecular basis of this immunity meltdown wasn’t well understood.

In the mid 2010s, He and his then-graduate student Bethany Huot found that even brief heat waves can have a dramatic effect on hormone defenses in Arabidopsis plants, leaving them more prone to infection by a bacterium called Pseudomonas syringae.

Normally when this pathogen attacks, the levels of salicylic acid in a plant’s leaves go up 7-fold to keep bacteria from spreading. But when temperatures rise above 86 degrees for just two days — not even triple digits — plants can no longer make enough defense hormone to keep infection from taking hold.
Further experiments revealed that the cellular machinery needed to start reading out the genetic instructions in the CBP60g gene doesn’t assemble properly when it gets too hot, and that’s why the plant’s immune system can’t do its job anymore.

The team was able to show that mutant Arabidopsis 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.

Next the researchers found a way to engineer heat-resilient plants that turned on the CBP60g master switch only when under attack, and without stunting their growth — which is critical if the findings are going to help protect plant defenses without negatively impacting crop yields.

The findings could be good news for food supplies made insecure by climate change, He said.
Global warming is making heat waves worse, weakening plants’ natural defenses. But already, up to 40% of food crops worldwide are lost to pests and diseases each year, costing the global economy some $300 billion.
At the same time, population growth is driving up the world’s demand for food. To feed the estimated 10 billion people expected on Earth by 2050, forecasts suggest that food production will need to increase by 60%.
When it comes to future food security, He says the real test will be whether their strategy to  protect immunity in Arabidopsis plants works in crops as well.

The team found that elevated temperatures didn’t just impair salicylic acid defenses in Arabidopsis plants — it had a similar effect on crop plants such as tomato, rapeseed and rice.

This is not the only way in which climate change is affecting agriculture, but it’s definitely a big one. What’s neat about this is that the researchers have also made progress on figuring out how to combat this effect, at least partially:

Follow-up experiments to restore CBP60g gene activity in rapeseed thus far are showing the same promising results. In fact, genes with similar DNA sequences are found across plants, He says.

In Arabidopsis, keeping the CPB60g master switch from feeling the heat not only restored genes involved in making salicylic acid, but also protected other defense-related genes against warmer temperatures too.

“We were able to make the whole plant immune system more robust at warm temperatures,” He said. “If this is true for crop plants as well, that’s a really big deal because then we have a very powerful weapon.”

This is good. I still think we need to move food production indoors, but that’s going to be at least as big of a task as ending fossil fuel use, and anything we can do in the meantime to increase crops’ resistance to heat will save lives. If you’ve been paying attention to farmers recently, you probably already know that food prices are likely to spike in the next few months. That’s due to a mix of factors, but global warming is definitely part of it, and it’s going to become an increasingly big part as the years drag on. That’s also going to be compounded by the ways in which the heat will affect us, both physiologically, and through deprivation of necessary resources and conditions. There’s been a lot of talk about how we’re likely to have more pandemics soon, but I haven’t heard much said about how that will be exacerbated by humanity simply being less resilient due to the constant pressure of climate chaos.

As always, we have the solutions, we just also have a political and economic system designed to prevent change, no matter the harm that does. We desperately need to build a different system.

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  1. StevoR says

    86 degrees! Ah, Fahrenheit not Celsius where its actually 30 degrees in Celsius.

    When it comes to food prices I don’t know about in the States but here in Oz the high price of lettuce of all things has become a major shock and focus of public attention.

    As soemone witha great interst inlocal native plants and living in one of the hottest driest states rising tmperatures and increasinglysevere heatwaves and droughts are a big worry although lately we’ve been more affected by flooding due to repeated LaNina’s.

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