The Genetic Adaptations for Heat Survival of Arizona Honeysweet in Death Valley

 

The Genetic Adaptations for Heat Survival of Arizona Honeysweet in Death Valley

Benjamin Pruss
BIOL-2110-001 GENETICS
Professor Guy F. Barbato
November 7th, 2025

    Most plants don't survive very well in extreme heat, much less thrive. However, the Arizona honeysweet (Tidestromia oblongifolia) does just that— in Death Valley, no less. All because of a unique cellular ability it has.

    T. oblongifolia can change the shape of the chloroplasts within its cells, the organelles that convert light, water, and carbon dioxide into energy and oxygen. Chloroplasts are usually disc-shaped; however, the Arizona honeysweet plants' chloroplasts can change to a cup shape. Although not certain, scientists believe this shape helps the chloroplasts better trap carbon dioxide. This, combined with other plant responses to heat, such as smaller leaves, allows the plant to thrive in Death Valley's extreme heat. 

    In an experiment conducted by Karine Prado and her associates, Arizona honeysweet growth was measured at 31°C and 47°C, the usual summer temperature in Death Valley. Seeds grown under Death Valley conditions grew significantly larger than those grown at 31°C. This suggests that the plant actually grows better under such harsh conditions. "These plants wait [for] the hottest month just to grow fast," said Prado about the plants. Some scientists believe that this plant's special adaptations could help future crops survive global warming. 

Sources:

https://www.sciencenews.org/article/death-valley-shrub-survival-heat

https://www.sciencedirect.com/science/article/abs/pii/S0960982225013120

PCR for Peanut Chloroplast DNA

This article from Science Daily summarizes a recently published article in the Journal of Agricultural and Food Chemistry about a new method involving DNA to detect trace amounts of peanuts in baked goods, chocolate and tomato sauce. This is extremely practical in the sense that peanut allergies are one of the most common allergies, and there are at least 3 million people in the US alone that suffer from this type of food allergy (1). A lot of people with this type of allergy can suffer from anaphylaxis when the allergy is triggered, even from only trace amounts of peanut. Anaphylaxis can be life-threatening and usually involves breathing difficulty, rashes, and nausea;  if not treated with the Epipen, it can lead to unconsciousness or death in extreme cases.

The team chose to study the chloroplast DNA of the peanut for several reasons. First, there had been previous research involving testing for the proteins in the peanut. This research is effective, but many of the proteins in peanuts can be destroyed during food processing. The nuclear DNA in the peanut can also be tested for with PCR, or polymerase chain reaction. However, it may prove challenging to find nuclear DNA sequences unique to only the peanut. The team wanted to try a new approach with chloroplast DNA in peanuts because chloroplasts are more abundant in the peanut compared with having only one nucleus per cell. The peanut chloroplast DNA is unique to the peanut only, so the team did not have to worry about overlapping sequences with other foods.

The team was able to successfully use PCR to test for three sequences in the peanut chloroplast DNA. Having three regions to test made their results even more convincing that the DNA is from peanuts, and not any other plant. The PCR successfully detected trace amounts of peanut in all of the food they tested, and were able to test for the peanut traces as low as 1 PPM. This is an improvement upon the 10-50PPM limit in PCR that tests for peanut nuclear DNA.

The reason I chose this article and enjoyed it was because of my personal connection. I have a severe egg allergy, and it too can be set off by trace amounts of egg, and it can even be triggered by breathing in the air containing eggs. I understand how serious these allergies can be because there can be cross-contamination with pots and pans and that is enough to trigger an allergic reaction. I am very happy to know that PCR can now detect trace amounts of peanut chloroplast DNA, but eggs do not have chloroplast. Maybe another team can develop a PCR method that detects mitochondrial DNA unique to eggs. It makes me very happy to know that there is research out there that is helping food allergy suffers make their lives a little easier. Maybe one day they will invent some kind of food scanner that can tell an allergy sufferer if the food contains the allergen. We're not there yet, but maybe one day.


Related article:

Scientists Have Identified A Key Gene Linked To Peanut Allergies

Genes outside the Nucleus “Punch above their Weight”

While DNA is found mostly in the nucleus, there are organelles in human and plant cells that also contain genetic material. These organelles include mitochondria for human cells and chloroplast for plant cells. It has recently been discovered that the DNA contained in these organelles is important as well. When scientists looked at genes found in chloroplast in 300 species of Arabidopsis plants, they found that they influenced concentrations of sugars, metabolites and amino acids. The fact that this powerful DNA lays outside the nucleus is groundbreaking discovery. It was known that these genes existed outside the nucleus however the degree which they affected metabolism has recently been discovered.  They believe this research can open new pathways for treatment for diseases such as obesity. In terms of vitro fertilization therapies it is believed that damaged mitochondria is being passed from mother to child. A treatment option that is being looked into is removing the nucleus from the mitochondria of the faulty egg and replacing it with healthy mitochondria. The new egg can then be fertilized. This method has been tested on animals however the interactions between mitochondria DNA and nucleus DNA is not fully understood so more research needs to be done. By shifting attention away from nucleus DNA and looking at organelle DNA we may be able to better understand certain diseases.    

Link:

http://www.insidescience.org/content/genes-outside-nucleus-punch-above-their-weight/1456

Related Links:

http://news.ucdavis.edu/search/news_detail.lasso?id=10743

http://mda.org/publications/facts-about-genetics-and-NMDs/genes-outside-cells-nucleus