Scientists (Lekeah Durden, et al) investigated the effects of the endosymbiotic and entheogen producing fungal species, Periglandula sp. as a defensive measure for Ipomoea tricolor (Morning Glory) against infection by soil nematodes infection. Periglandula fungi can only survive inside the tissues of host plants and grows into every part of the plant, even the seeds to ensure propagation to future generations. As fungal cells accumulate they also provide protection through the simultaneous production and accumulation of ergot alkaloids to reduce or prevent herbivory and parasitism.
*Updated 10/14/2022 with Citation for titular Article at author's request [10]
Article Hypothesis and Author Note
Organisms, living together and mutually benefiting each other, exist throughout the planet's ecosystems. From mutualistic lichens (fungi-algae) to photosynthetic sea slugs (slug-algae), symbiotic relationships emerge again and again in the branches of the tree of life. Knowing that these relationships depend on mutual benefit, the Scientists decided to investigate a known symbiotic relationship: Periglandula sp. x Ipomoea sp (Fig. 1). Historically, Ipomoea, also known as 'morning glory', has been cultivated for its beauty and physiological/pharmacological effects; however, the reason for which is as indirect as the previous symbiotic examples.
Based on the defensive mutualism hypothesis, an idea that both organisms in a symbiotic relationship must benefit [1], the Scientist proposed the "goal of this study was to test if fungal endosymbiont infection affects root-knot nematode gall formation and growth of I. tricolor." Furthermore, they believe that plants with Periglandula growing symbiotically "would exhibit decreased gall formation on the root system compared to E- plants [without Periglandula], consistent with the biological activity of ergot alkaloids." Thus their belief is strongly that the ergot alkaloids provide a defensive mechanism for the plant to help the plant grow, and thus benefit the endosymbiotic fungi.
Part of what I want "Understanding Entheogens" to be is a change in perspective towards the larger picture of what entheogens are: the evolutionary pressures that influence them, their chemical structures and production, and their impact on consciousness. Widening the scope, beyond just human consciousness, we begin to maybe understand the impact of why and where some of these compounds came from and why they are still being produced by so many organisms still. One of the reasons why I chose this article is because it helped me to better understand the complex nature of entheogens, their expression, and their possible purpose. I was aware of the fact that seeds of I. tricolor contained the precursor to Lysergic Acid Diethyamide (LSD) known as Lysergic Acid Amide (LSA), and always assumed it was produced by the plant. Later on in researching the parasitic fungal genus Claviceps, commonly known as Ergot, I began to understand the breadth of fungal roles in plants and the specific one entheogens play within biospheres.
Ergot Alkaloid Lineage of Defense
Numerous organisms throughout the floral, faunal, and fungal kingdoms produce compounds to prevent predation, or in the case of immobile plants and fungi, herbivory. From frog bufo-toxins to Nicotina stimulants; lots of those compounds affect the nervous system of consumers as hypothetical defenses [1]. Notably, a wide variety of these compounds have been utilized in appropriate doses as medication by humanity for generations and make up the wealth of entheogens explored by this blog. Of all the ergot alkaloids previously detected in wild Ipomoea tricolor, the lysergic acid amide ergine, was the most abundant. [7, 8] That being said, the same researchers also have "documented four [other] ergot alkaloids in roots of I. tricolor seedlings (Fig.2 ), raising the possibility that the alkaloids might have activity against below-ground pests and pathogens." [7] To test this theory they opted to bring in a competitor, the root-knot nematode Meloidogyne incognita. This obligate parasite induces the host plant to develop giant cells inside the roots which form visible galls, or knots, where the nematode lives and feeds off of the host plant. [9] The theory being that the presence of Periglandula and its constituent alkaloids would prevent the nematode from being able to parasitize plant roots.
Historical use of and modern distribution Ipomoea spp.
While the modern entheogen movement is gaining traction, it is always important to take time and acknowledge the wealth of information and insight provided by ancestral practice. In Spanish, Ipomoea species are also known as 'quiebra cajete blanco', or 'flor de la virgen', since it had religious connotations in the 16th century [4]. Further back in time, entire plants of I. violacea, called 'tlilitzin' in the time, were consumed by the Maya and Aztec for their entheogenic effects as well as to take consumers into trance states [4]. Nahuatl people called the plant 'ololiuhqui', and is very common and abundant in Mexico and the continental United States [4]. 'Ololiuhqui' is known to be a type of morning glory, named this way because its flowers close-up during the at dusk to reopen as the sun rises [4]. Commonly used by Mixtec and Zapotec peoples in the state of Oaxaca, Ipomoea seeds, leaves, and stems are still consumed to this day by the local healers who conduct curative and divination ceremonies [4].
Even though Ipomoea sp. is widely distributed throughout the tropical and sub-tropical regions of the American continents, they have been located historically in locations like Africa and Japan (Fig. 3). Depicted in art as old as the 12th Century in Japan, Ipomoea nil can historically be traced to numerous pre-Columbian prose, poetry, and paintings [3]. I. nil is called 'asagao' (朝顔) in Japan and is said to have been brought over by diplomats from China during the Nara period, which was around the 8th century. Generations of culture instilled the ideas of beauty and power in Ipomoea, which can be seen represented in the translated name 'asagao' which literally means morning 'asa' (朝); followed by 'honor', 'dignity', and/or 'face', 'gao' (顔) . The plants are rumored to have been used as a medicine and cherished for their beauty by the noble castes of East Asia throughout 8th-12th century.
Lifestyle Semantics: Parasitic, Rhizomorphic, and Symbiotic Fungi
Understanding the ecological roles of fungi requires a bit of language review to help put into perspective location and function. Endo- is a Greek-based prefix meaning 'inside', typically used in parallel to Epi- 'outside'; thus an endosymbionts are symbiotic organisms that live inside the tissues of their host partner. Staying on in the same semantic space, Rhizo- is also Greek-based meaning 'root' and typically describes the soil environment around plant roots. Within this, mycorrhizal spaces, i.e. 'fugnal-root', exist so fungi can intermingle with tree roots; growing into and around each other to share nutrients. An organism that is parasitic, can be understood in Greek as Para or 'along-side'; and sitic or 'eating-from-another's-table'; better known in modern terms as a 'free-loader'. Knowing this, we can see the opposite in Symbiotic relationships, again lifted from Greek-based as sym or 'companion' and biotic or 'living-together'.
Most parasitic fungi exist the majority of their lives as endoparasites, inside-living parasites, that only expose themselves when they are ready to produce their fruiting bodies like Claviceps purpurea, Epilcloe typhina, Ophiocordyceps unilateralis or Massaspora cicadina (Fig. 4). In mycorrhizal spaces there exists soil fungi that sometimes grow in between the cells in plant roots, others around plant roots, and still more in coils along plant surface cells; all with the intent to exchange nutrients, typically sugars from the plants, for nitrogen or other harder to get macro nutrients extracted from the soil by the fungi (Fig. 5). However, Periglandula ipomoeae, a mutualistic fungi that hosts in Ipomoea spp., exists in a state of endosymbiosis with it's mycelia growing into and around plant cells, even growing into seeds of the plant for future generations to benefit (Fig. 1).
Conclusion and Caveats
The Scientist were able to grow and test numerous different conditions of growth with the three organisms in question: Ipomoea plants, Periglandula fungi (E+/E-), and Meloidogyne nematodes (N+/N-). Isolating plant seeds were 'cleaned' of fungal cells (E-) and were raised in soil with nematodes (N+) and without (N-). The same was repeated with 'wild type' plant seeds with fungal cells (E+). Based on raw, nematode-induced, gall number counts; those plants with the endosymbiotic fungus produced half as many galls on average as those without (Fig. 6). Furthermore, the presence of nematodes tended to parallel lower alkaloid levels in root masses tested; but regardless of nematode presence, ergot alkaloids were detectable in all expected samples (Tbl. 1). As the Scientist say: "[Our] results support the hypothesis that alkaloid production by the endosymbiont reduces pest damage, but this protection may entail a trade-off with host biomass, at least at early stages of plant growth."
Going further to note a number of interesting points that deserve further investigation as well. They believe there is a possibility of soil leaching of ergot alkaloids that might influence the rhizosphere ecosystem and co-occuring plant species. They suggest that planting a crop of I. tricolor in rotation might help improve soil quality for crops by reducing endemic nematode populations. Furthermore, they imply that ergot alkaloid leaching might play a role in the increased colonization rates of 'morning glory' plants into new ecosystems.
Support or Reject Hypothesis?
The role of symbiotic fungi Periglandula in host plant Ipomoea defense is supported by the reduction of gall formation and nematode infection relative to the presence of fungal-based ergot alkaloid accumulation; which was not only noticeable, but statistically significant in their difference.
Reviewing the data and the conclusions put forth, the hypothesis proposed by the Scientists was supported. The reason(s) for acceptance are quoted below (emphasis and parentheticals mine):
"Our results indicate that presence of the Periglandula fungal endosymbiont (E+) significantly decreased M. incognita gall numbers on I. tricolor root systems by 50% compared to [plants without endosymbiont (E-)], and that this result was not dependent on the size of the root system."
"E+ plants also accumulated Periglandula-produced ergot alkaloids in their roots, whereas E- plants were alkaloid free. Both symbiosis and nematode colonization had a significant effect on plant biomass where both N+ and E+ treatments decreased host plant biomass after 4 weeks of growth in the greenhouse relative to N- and E- controls."
References
1) Clay K. Fungal endophytes of grasses: a defensive mutualism between plants and fungi. Journal of Ecology 1988, 69:10–1.
2) Florea S, Panaccione DG, Schardl CL. Ergot Alkaloids of the Family Clavicipitaceae. The American Phytopathological Society May 2017, 107(5): 504-518.
3) Austin D, Kitajima K, Yoneda Y, Qian L. A putative tropical American plant, Ipomoea nil (Convolvulaceae), in pre-Columbian Japanese art. Economic Botany 2008, 55: 515-527.
4) Carod-Artal FJ. Hallucinogenic drugs in pre-Columbian Mesoamerican cultures. Servicio de Neurologia, Hospital Virden de la Luz, Cuenca, Spain December 2015, 30(1):42-49.
5) Steiner U, Leistner EW. Ergoline Alkaloids in convolvulaceous host plants originate from epibiotic clavicipitaceous fungi of the genus Periglandula. Fungal Ecology June 2012, 5.
6) Wikimedia Community Commons Image Links:
7) Beaulieu WT, Panaccione DG, Hazekamp CS, Mckee MC, Ryan KL, Clay K. Differential allocation of seed-borne ergot alkaloids during early ontogeny of morning glories (Convolvulaceae). Journal of Chemical Ecolology 2013, 39:919–930.
8) Nowak J, Woźniakiewicz M, Klepacki P, Sowa A, Kościelniak P. Identification and determination of ergot alkaloids in morning glory cultivars. Analytical Bioanalalytical Chemistry 2016, 408:3093–3102.
9) Escobar C, Barcala M, Cabrera J, Fenoll C. Overview of root-knot nematodes and giant cells. Advanced Botany Resources 2015, 73:1–32.
10) Durden, L., Wang, D., Panaccione, D. et al. Decreased Root-Knot Nematode Gall Formation in Roots of the Morning Glory Ipomoea tricolor Symbiotic with Ergot Alkaloid-Producing Fungal Periglandula Sp. J Chem Ecol45, 879–887 (2019). https://doi.org/10.1007/s10886-019-01109-w