Sister Morphine

Although I’ve met and friended folks who claim they’ve seen it, I’ve never witnessed a plant that could run. Instead, they engage in chemical warfare or communication. The chemicals are the result of multi-step metabolic networks that provide the chemical apparatus to change the staring material into a bioactive substance. Such a chain of chemical reactions is controlled by a series of proteins, called enzymes. Each protein is coded for by a gene.Poster_papaver_3a

This research identified a large cluster of 15 genes that encode enzymes in the metabolic pathway with morphine as an endpoint. Approximately 50 alkaloids are found in Opium poppy (Papaver somniferum), with morphine the largest in concentration.

According to the study, the pathway for the painkilling drugs evolved around 7.8 million years ago (mya). Primates are presumed to have appeared 63 mya, Hominidae (precursors to modern humans) 15 mya, and humans 1.3-1.8 mya. First recorded humans use appears in 5000 BCE in the Neolithic age. The PBS show Frontline provides a timeline of human use. It’s history shows that Morphine has been a “wonder” drug for pain, and a bane for those addicted to it and it’s derivatives

The mechanism responsible for euphoria also kills. Morphine binds to receptors in the brain, inhibiting neurotransmitter release and resulting in among other physiological changes, pain relief, but also slowed breathing.  Overdose victims often stop breathing.

Since the plant has been around for quite some time, I wondered if there were any histories to show animals consuming this or other plants to reduce pain or to  give pleasure? A brief review showed the following:

  • Researchers discovered it was chili peppers. Next, they studied tree shrews in the wild and discovered they ate one particular pepper, the Piper boehmeriaefolium, and actually preferred to eat it over other plants and vegetation.
  • Scientific Reports provides evidence that Borneo based apes chew leaves of the Dracaena cantleyi plant to create a white lather, which they then rub onto to their bodies
  • A study of chimps found that they roll Aspilia leaves for a period of time (they are very bitter to chew). This plant material contain thiarubine A , which kills harmful bacteria, and fungi because they contain thiarubine A, a powerful antibiotic. Research also suggests these leaves act as a stimulant, since chimps ingest them first thing in the morning.

What’s more compelling is the rich association of the opium poppy with war.  with a few examples below. One aftermath of each – the trail of addiction that followed either the imposition of trade or the use of morphine on the battlefield to reduce pain from horrible damage.

  • During the 18th century, forcibly exported opium to China, even while it was banned in Britain because the government and industry knew it was not good for the populace in general. It took two opium wars, eventually disrupting the country and leading to the  collapse of the Qing Dynasty.
  • After World War I in remembrance of the fallen soldiers, the living commemorate the sight of thousands of blood-red poppies appearing on the battle-scarred fields of Flanders, in Northern France.
  • US wars in Vietnam and Afghanistan have been greatly affected by opium production supporting the opposing militaries ability to pay for the fighting.

Now America is facing a public health crisis of opioid addiction.  In an interesting turn, last November, President Donald Trump asked Chinese President Xi Jinping to help stop the “flood of cheap and deadly” fentanyl from China into the United States.  Fentanyl is a synthetic opioid, 50 to 100 times stronger than morphine.

For better or worse, this is an example of co-evolution – humans identifying and applying a plant to alleviate the pain they, themselves create.

Listening in on someone else’s conversation

This paper in Science, investigated molecular conversation between a parasitic plant, dodder (C. pentagona), and two host plants, by sequencing all three transcriptomes.

Genes, defined segments of DNA (deoxyribonucleic acid), must be “read” and copied (transcribed) into RNA (ribonucleic acid). These gene readouts are called transcripts, and a transcriptome is a collection of all the gene readouts present in a cell, The major type, of gene readout is called messenger RNA (mRNA), which plays a vital role in making proteins that can have a profound impact on an organism. The production of these proteins can vary, depending on both environmental and genetic influences.

The researchers found thousands of mRNAs moving in a bidirectional manner between species. These transcripts represented thousands of different genes. Researchers think this molecular conversation might allow the parasitic plant to direct the host plant to dampen its defense responses.

Since we also contain ancient, and potentially active viral or bacterial transcriptomes in our genes, at least some of the voices we hear are real.

Blood is Blood, But What About Photosynthate?

Scadoxus multiflorus subsp. katherinae, Common...
Scadoxus multiflorus or Blood flower (Wikipedia)

Is it really so odd to consider kin recognition in plants? Plant roots grow more in proximity to genetically related plants (Bhatt) and the recognition of kin is based on chemicals secreted by the roots (Biedrzycki).  In a recent paper in New Phytologist, Crepy and Casal noted that plants also react to kin in the aerial portions; first by reorienting leaf growth when growing near kin, but not near unrelated plants of the same species; and secondly, by producing more seeds when interacting with kin vs. nonkin.

Can we then consider plants connected via mycorrhizal associations step families?

References:

  • Bhatt, MV, Khandelwal, A, Dudley, DA. (2011) Kin recognition, not competitive interactions, predicts root allocation in young Cakile edentula seedling pairs. New Phytologist. 189: 1135-=1142.
  • Biedrzycki, ML, Jalany, TA, Dudley, SA, Bais, HP. (2010) Root exudates mediate kin recognition in plants. Communicative and Integrative Biology. 3. 28-35.
  • Crepy, MA and Casal, JJ. (2014) Photreceptor-mediated kin recongition in plants. New Phytologist. 205: 329-338.

 

It’s in the Dirt

Arbuscular mycorrhiza seen under microscope. F...
Image via Wikipedia

Well, dirt plus nutrient content. Organic farmers know that it’s really about the soil. In particular, the “living” component of the soil. Researchers are now catching up with findings that help explain why soils on organic farms and in native woodland ecologies have greater concentrations of fungal spores in the soil and greater levels fungal colonization of plant roots – particularly the symbiotic or helpful fungi.

Mycorrhizal fungi form a symbiotic relationship with plant roots, each exchanging benefits with the other. The plant gains phosphorous from the extended “root-like” threads of fungal hyphae, while the fungi absorb glucose stored in plant root cells, which was originally metabolized (made) by the plant during photosynthesis. Additional benefits these fungi provide the plants include enhanced disease resistance, soil stability and structure, as well as nitrogen fixation.

However, the fungus cannot be cultivated in the absence of a host plant root. Commercial farming often suffers from dead soil. The USDA’s Eastern Regional Research Center (ERRC) focuses research on the use of mycorrhizal fungi to improve crop quality and yield. Researchers at this facility try to understand the necessary chemical signal exchanged between plant and fungus required during the various stages of fungal development. Their aim is to grow the fungus on artificial media without the presence of plant roots. Because of the numerous benefits that mycorrhizal fungi provide, commercial farmers hope that a fungal inoculum could then be used to limit the amount of fertilizers applied to large scale crops while still improving plant growth and health.

I’ll come back to the way plant and fungus woo each other, whispering sweet chemical cross talk…

 

Unique Germination Characteristics of Goldenseal Seed

goldensealUnderstanding dormancy requirements for woodland, medicinal plant species is a requirement for discovering how they initiate their relationship with soil fungi. Sanders & McGraw (2002) noted that despite wide geographic distribution, seedling establishment is a constraint in wild goldenseal (Hydrastis canadensis, L.) populations. Richo Cech, of Horizon Herbs, has been quite successful teasing recalcitrant, deep-forest medicinal species to break dormancy using forest propagation studies (2002). Baskin and Baskin (2014) noting that goldenseal was a two-phase germinator, with some seed germinating only as root tissue and lacking aerial development until the second year. They indicated that this appeared to be a developmental pattern found in several native plant species growing in the same habitat as goldenseal.

From the stand point of understanding the chemical ecology of medicinal plants, this may allow the roots to interact with the rhizosphere community of fungi longer and, in the case of goldenseal, to develop the anti-microbial alkaloid pool necessary for defense of aerial growth the following season. In a closely related plant family, Berberidaceae, alkaloid production in Berberis vulgaris occurs immediately after seed germination and increases with seedling age (Pitea et al. 1972). This suggests that the medicinally active alkaloids in root tissue are important to the defense of the plant seedling from the onset.

Data is lacking on goldenseal rootlet interactions with rhizosphere fungi post-germination. Initial screenings of mature, wild goldenseal root populations (Tims, 2008) indicated that arbuscular mycorrhizal fungal (AMF) were not associated with either root or seed tissue, and that AMF spores were not found in the rhizosphere soil of the plant. Goldenseal roots did appear to form an endophytic relationship with a zearalenone (ZON) producing Fusarium oxysporum, normally associated with pathogenic characteristics (Tims and Bautista, 2007).

Zearalenone (ZON) has reputed auxin-like (plant hormone) effects on plant tissue, promoting development of lateral roots (Celenza et al. 1995), and stimulating root tip growth (Bean et al. unpublished). These are regions of the root where soil fungi would attempt to enter the plant tissue. In contrast, this particular endophyte appeared to co-exist within the plant root without causing obvious signs of ill health. It is possible that the production of ZON by Fusarium may affect meristematic activity in H. canadensis emerging from dormancy by initially stimulating rootlet formation and root exudation. Rootlet interaction with ZON during the early phase may benefit the plantlet by increasing plant secondary metabolite formation.

Tims and Bautista found that an alkaloid in mature goldenseal root tissue, hydrastine, inhibited ZON production in the endophyte. Cech (private communication) collected cultivated goldenseal from Kentucky and Oregon, and found that berberine levels were higher in the leaf and hydrastine levels higher in the root.  This too would corroborate the results by Shitan et al. (2005) that an ABC pump moved berberine from root tissue to aerial portions of the plant. The interplay between ZON produced by the fungus and hydrastine found in goldenseal root would appear to  have a two-fold effect. Hydrastine may limit more aggressive pathogenesis of the root tissue by F. oxysporum, while ZON may stimulate the production of hydrastine in developing goldenseal root. An additional developmental question that needs to be explored is to what degree might the presence of ZON, or similar microbial compounds in the rhizosphere, favor or induce two-phase germination?

References:

  1. Bean, GA. (1999) Unpublished.
  2. Baskin, CC and Baskin, JM. (2014) Seeds: Ecology, Biogeography, and, Evolution of Dormancy and Germination, 2nd Edition. Academic Press: Cambridge, MA.
  3. Cech, R. (2002) Growing At-Risk Medicinal Herbs: Cultivation, Conservation, and Ecology. Horizon Herbs Publication, Williams, Oregon, pp.41-51.
  4. Celenza JL, Grisafi PL, Fink GR (1995) A pathway for lateral root formation in Arabidopsis thaliana. Gene Dev 9: 2131–2142.
  5. Pitea, M, and Margineanu, C. (1972) Correlations between Chemical Structure and Antibacterial Activity of Berberine. Clujul Med 45:465.
  6. Sanders, SM, and McGraw, JB. (2002) Distribution, Abundance, and Population Dynamics of Goldenseal (Hydrastis canadensis L.) in an Indiana Nature Preserve, USA. Nat Areas J 22:129.
  7. Shitan, N, Kiuchi, F, Sato, F, Yazaki, K, and Yoshimatsu, K. (2005) Establishment of Rhizobium- Mediated Transformation of Coptis japonica and Molecular Analyses of Transgenic Plants. Plant Biotech 22:113.
  8. Tims, M.C. (2008) The Chemical Ecology of Goldenseal (Hydrastis canadensis L., Ranunculaceae): How medicinal plants roots control the microbial communities in their rhizosphere. VDM Verlag, Saarbracken Germany.
  9. Tims M.C. and Bautista C., (2007) Effects of Root Isoquinoline Alkaloids from Hydrastis canadensis on Fusarium oxysporum isolated from Hydrastis Root Tissue, Journal of Chemical Ecology, 33:1449–1455.

Co-Evolution of Humans and Plants

How do you interact with plants? ? Why do you interact with plants?

brussel sprouts

We respond to a spectrum of sensory effects

  • visual – pigments
  • taste – spice
  • smell – aromatic oils
  • effect – pharmacologically active

Evolutionarily speaking, it remains unclear whether pharmacological use of plants by humans was more prevalent before or after the development of agriculture led to cultivars with reduced biological activity compared to the wild types. Dr. Fatimah Jackson, at the University of Maryland, College Park, argues succinctly that cultural evolution – driven by language – became the driver influencing the extent of human interaction with plants. Dietary preferences are central to how cultures self identify and define. According to Daniel Moerman at the University of Michigan, Native Americans used plants in a 5:1 ratio as medicine and food. Over time humans have learned how to limit their exposure to toxic plants. I imagine a group of early humans going out as a group and asking ‘Mikey’ to try the plant first. If he lived, ‘Mikey’ discovered how to modifying plants’ palatability, nutrition, toxins and to amplify beneficial effects through various means – extraction, heating, drying, and fermentation to name a few. What examples exist from your own cultural heritage of unique use of plants and their chemistry?

Is this a form of co-evolutionary symbiosis between humans and plants? I would argue that humans have had profound effect on the genotype and phenotype of cultivated plants, while plants have provided nutrition, medicine, and the early stimulus for our enzymatic detoxification system and possibly for language development in the brain (synaesthesia – discussed in a future post).  Dietary exposure to continuous low levels of plant mutagens would certainly effect mutation rates or genetic drift. I would highly recommend an article by Dr. Jackson on human-plant-parasite triads as evidence for coevolution.

Consider the next you avoid eating your bitter tasting brussel sprouts – if you don’t eat them, are you de-evolving?