Plumalmondterine

My one boss is involved in this big peach breeding project that's been running for, I think, decades. He's responsible for disease screening assays on thousands of fruits from different crosses that are produced each summer. One of the universal benefits of working in an ag lab is that we get lots of leftovers every week.

This week's peaches were pretty interesting. A bunch of them looked like normal nectarines, but when you bit into them, they tasted more like plums and had deep red-purple flesh. The skin was a little rubbery like a plum too. We thought this was pretty remarkable until we got down to the pit. There was an almond inside! It was like a fruit that came with a dessert at the end!

This week's peaches turned out to be hybrids between peach and almond trees (all three of these trees are very closely related to each other, in the genus Prunus - along with apricots and cherries). This got me thinking about the extent to which our food supply is made up of completely artificially-selected genetic freaks. Much of what we eat barely resembles any plant you could find growing wild out in the woods. Traditional breeding techniques have produced varieties far more bizarre and "unnatural" than anything so far engineered with molecular biology techniques. One day that won't be true, but currently our genetic engineering is pretty simplistic.

It's kinda funny that the vast majority of people are much more concerned about genetic engineering than traditional breeding right now despite the safety record of GMOs, which is arguably better. This is completely understandable. I think it's a really good example of how common sense intuition often turns out to be a pretty unreliable method of divining reality. People were really scared of vaccines when they were invented too. This was another technology that sounds like a really terrible idea at first, but turns out to be an invaluable tool when you have the nitty gritty down. These are both normal first reactions for rational people, I think. At least in comparison to more far-out ideas like "intuiting."

Intuiting is a term that some mycophiles have used to describe the putative (and false!) idea that humans can determine if a wild mushroom is poisonous or edible by their impression of it. I guess some people are really eager to find shortcuts around such boring pursuits as scholarship. Why study which potential foods will kill you if you think you can just believe you have an innate ability to sense if something is "good" or "bad" for you? The naive idea that the world is split into dialectic opposites of black and white points toward the gray.

There's a lot of subtle variation in the botanical world. Sometimes single species of fungi or plants exhibit huge ranges in concentrations of potentially poisonous or toxic chemicals. Wild almonds are toxic because they produce cyanide when broken. It's thought that domesticated almonds (which obviously don't produce cyanide) are descended from a mutant wild almond that failed to produce cyanide.

I don't think the metabolic pathways and regulation for cyanide production are really known in Prunus. When my friend who works in an almond lab heard that me and my lab mate had tasted the apparent peach almond he was a little alarmed. Apparently this kind of haywire genetic mixing happens a lot in Prunus species and it's happened before that a fruit is produced that looks like chimera of a few different fruits that we think of as distinct.

I still think this would be a great variety for the supermarket or farmer's market. It's a hell of a lot better than a "Grapple" at any rate. In the end, with breeding or GMOs, it all comes down to empirical testing. You can't always predict whether something is a good idea just based on experience or established theories. New foods and new versions of old foods just need to have an eye kept on them to make sure no unexpected poisons or other hazards creep in.

Do this, and all this new fruit will need is a name.

Devourer of Radiation

I'm surprised that I had forgotten about this story until I caught up on my article reading list this afternoon.

Ionizing Radiation...Enhances the Growth of Fungi - PL0S 0ne

(this open access journal is part of a audacious federal project worthy of its own post...coming soon)

But anyway, here's the punchline:

Some fungi may be capable of consuming radiation.

The story:

Melanin (the pigment in your skin that protects you from the sun) is an amorphous aromatic polymer that plays many different roles in many different organisms. Fungi use melanin both as a shield against the environment and a weapon against hosts (another story I intend to follow up on). Melanin has been well documented to shield cells from the damaging energy of electromagnetic radiation, such as UV light, by both absorbing and scattering photons and electrons. The authors of this paper set out on this topic with the hope of characterizing the physico-chemical changes that take place when melanin molecules intercept light.

In the process of their experimentation, they noticed that three species of melanized fungi grew significantly more (by four measures) when they were irradiated than when they were not. They also observed that melanin was capable of increasing the redox reaction of NADH and ferricyanide when irradiated (by passing electrons between the two chemicals).

Towards the end, the authors review previous indirect evidence for the idea that radiation is beneficial for the growth of some melanized fungi. One species has been found to be radiotropic - preferentially growing towards sources of radiation. This organism, Cryptococcus cladosporiodes, has become very common in the region surrounding Chernobyl since the meltdown. In both lab and field studies, other species of melanized fungi have been found to grow towards radionuclide-cotaminated soil particles, which were then apparently consumed.

So it may be possible that some melanized fungi are able to live off radiation (both electromagnetic and from decaying radioactive particles), I presume, by capturing photons/electrons like chlorophyll pigments and passing them down the electron transport chain.

Maybe we can turn all the nuclear waste holding tanks around the country into fungal fermenters instead of fighting the NIMBY monster of Yucca Mountain.

Orthotydeus lambi!

One of the most interesting talks I saw at APS was David Gadoury's "Very small sheep." He began by describing how his group failed to detect significant epidemics of powdery mildew (a plant-infecting fungus) on a wild species of grape (a plant that is very susceptible in conventional agriculture). In greenhouse experiments, these wild grapes were just as susceptible as agricultural grapes to powdery mildew when inoculated. They discovered that a species of wild mite, that occurs throughout the United States, control powdery mildew of wild grapes by roaming their leaves and grazing heavily on the spores and mycelium of the parasitic fungus.

They then asked themselves if these mites lived in commercial grape fields, and if not, if something could be done to encourage their presence. They first suspected that the mites were absent from commercial grape varieties because these varieties have many fewer "hairs" than the wild species - and these mites are thought to rely on these hairs in order to hide from predatory mites. But despite having fewer "hairs," known as domatia, mites seemed just as happy to live on commercial varieties - in fields that weren't sprayed with pesticides...

Agricultural grapes are routinely treated with pesticides to control damaging insects and fungi, so they ran an experiment comparing mite populations in grape fields treated with different pesticides. Ironically the "organic" fungicide, sulfur, killed the mites, but some of advanced synthetic fungicides didn't hurt the mites, at least not at lower application rates. One member of the audience, possibly hoping for an organic solution, asked if mites might be found that were resistant to sulfur. David replied that it was not possible, and that you might as likely find an organism that's resistant to "fire" - reflecting the extreme toxicity of this "organic" biocide.

They then tried to see if mites could control powdery mildew in the absence of pesticides. It turns out they could - but not to economically acceptable levels. In the end, the best treatment was a low level of fungicide that controlled powdery mildew partially, yet allowed mites to exist to control the rest. Not a pesticide-free solution but certainly better than the original!

San Diego Conference 2007 - no, not comic con

Well, I just got back from the APS conference in San Diego this afternoon. Several of my colleagues felt somewhat let down by this meeting. It seemed that many of the talks and posters lacked the quality of, at least, last year's meeting in Quebec City. I imagine it was just bad luck which labs decided not to attend this year. At any rate I have two stories in preparation for you.

The first was a pretty exciting talk by David Gadoury of Cornell. Biocontrol, the use of predatory/parasitic organisms to control pests in place of pesticides, has long been a holy grail of plant pathology. His talk described (a very rare!) example of a native organism controlling severe epidemics of a serious plant disease in a mainstream agricultural crop. Successful biocontrol is virtually unprecedented as it is, but this talk interested me additionally for the system's apparent sheer practicality, and interesting interactions with pesticide applications (hint* synthetic helps, organic ruins!). more coming soon...

The second story I have is based on a presentation by Dennis Avery of the Hudson Institute. He started off his presentation with a scathing assessment of several "green" solutions to the status quo such as organic ag and biofuels. To the extent that he spoke within subjects I've studied (~80% of his points), he was dead on (with very clever and informative examples) but he also ventured onto potentially thinner ice - e.g. denouncing any correlation between human artifacts (specifically elevated CO2 levels) and global warming. I've never really taken the time to look at the evidence for this myself, but after his talk I feel this is pretty intellectually (and literally) lazy. The way the media has handled scientific topics from organic ag to stem cells really calls for everyone to start taking more responsibility to critically evaluate "facts" that they're presented with.

At any rate, the story I'm preparing will include some research into the goals and financial backers of this institute and associated individuals. At the very least, I'll share my notes from his presentation (hopefully with some stats-checking and link to his power point file).

I'll follow up with a look into the primary source evidence for anthropogenic global warming. In the unlikely case that we don't have good evidence that human industry causes significant global warming, it would be foolish to waste conservation cash and effort on this specific goal.

cheers!