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Plants & People: The Intersection of Botany and Human Experience

Evolutionary Phylogeny of Eragostis Based on Chloroplast Genome

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1. Evolutionary Phylogeny of Eragostis Based on Chloroplast Genome
Contents of this annotation:
1. Evolutionary Phylogeny of Eragostis Based on Chloroplast Genome

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Eragostis tef: From Injera to fertility and everything else in between Teff is a unique member of the grass (Poaceae) family that is a staple in East Africa and accounts for a large portion of East African diets. Teff, known for being the plant with the smallest seeds, is a labor intensive crop that is necessary in Ethiopian and Eritrean cuisines. This necessity is born from the traditional usage of Teff flour being used in the fermentation and creation of Injera, a sour spongy flatbread. This demand of Injera, and therefore Teff flour, has led to 31% of Ethiopian landmass being used for the cultivation of Teff. The agronomics of Teff are interesting in that Teff can only thrive in climates similar to the East African Highlands and the planting and harvesting of Teff are known to be labor intensive due to its rooting pattern and its small grain size. Teff itself has multiple physiological variations ranging from varying colors for both the seeds and the plant to variations in Amino Acid, Protein, and nutrition profiles. Teff’s stability as a choice crop in East Africa is accredited to its hardiness to survive drought and water logged conditions when rooted in the proper soil conditions, shelf stability, and the straw can be used for livestock forage feed. Teff is thought to originate some time around the 6000 B.C, but cultivated at some point around 2500 B.C as the earliest known record of Teff, is seeds found in bricks of the Dahshur Pyramids, most prominently the Red Pyramid of Sneferu. By Luis Angel Yepez #tef

Nomenclature and Naming
The linnaean binomial nomenclature is Eragrostis tef, of which the first comes from greek “ἔρως” and “ἄγρωστις” meaning love and grass, respectively. "Tef" comes from the Amharic “teffa” meaning lost, due to teff’s small grains. Indigenous names include amharic ṭēff (ጤፍ), oromigna tafi,and tigrigna Taf. Other common names for this plant are tef, William’s Lovegrass, annual bunch grass, tafi, and taf.
Evolutionary History
Eragrostis tef is believed to be descended from E. pilosa. Due to lack of archeological evidence that captures the process of domestication at any stage, there is little to no further knowledge of E. tef's evolutionary history. In these cases, a phylogeny using the genome of the species and believed ancestors and sister species is the best way to map this evolutionary history if we are looking at the tree with the most likelihood. In this phylogeny, 20 Eragrostis species are analyzed and positioned based on the complete chloroplast genome of each species. Here we can see that E. tef is part of a sister group to the monphyletic group that includes E. mionor and E. autumnalis. Its own monopphyltic group includes E. pilosa, E. cilianensis, E. nigra, and E. ferruginea.
Ecology and Life History
In terms of ecology, teff is adaptive because it can survive in both drought and water-logged conditions. However, it only grows healthily in east African highlands. There are few to none commercial growers outside of the horn of Africa have been successful, except for in Spain and in small fields in other areas that use it for animal forage feed.Teff is heavily adapted to the heavy clay soils of the highlands, as it grows between 1700-2200m, with Ethiopia being at 1800-2100m. Its largest yields and large scale cultivators are in Ethiopia. Teff is an annual C4 grass, and therefore it is harvested about 2-6 months after sowing. It is usually harvested when it has turned yellow in color, as brown, completely dry teff has the risk of losing most of the grains during the harvest as they fall out with ease when dry. Teff is planted in the warm, rainy seasons of late May in Ethiopia, and its germination rate is very fast for a grain. Seedlings will grow until mature, in which seeds will form, dry, and drop naturally if left alone.
Vegetative and Reproductive Morphology
Teff is a grass with a large crown, many tillers, and a shallow but diverse root system that can be very fibrous. The leaves are thin and flexible, and green before maturity. It’s stems are thin and bend easily. Total plant height varies from 25-135 cm, and panicle length can range from 11-63 cm. Panicles are spiked structures that grasses usually have; they are branched raceme, which are clustered inflorescences. Panicle types also vary from branched, loose, compact, among others. Grain colors also vary from light tan to brown colors. Teff seeds are very small, averaging around 1 mm in diameter.

Teff is a tetraploid (2n=40) and it self-pollinates to produce its seeds. The florets have a lemma (part of spikelet), palea (part of spikelet), two stigma, two lodicules, and 3 stamens. Floret colors range from white to dark brown.
Historical Accounts
Teff has been grown in the Horn of Africa for a minimum of 2,000 years. The earliest sites identiied to have cultivated teff were from the Ona Nagast, Northern Ethiopia, which had agricultural systems dating from as far back as 400 BC to 700 AD. The site was explored for organic materials, adn found that teff was among the grains used in this civilization. However, there were challenges that needed to be addressed, such as how to tell teff apart from wild Eragrotosis species. This has been a major deterrent in unraveling the history of this grain, as well as its very small size. Using charring methods and analysis made with a number of assumptions based on the nature of agriculture/breeding, researchers have been able to tell apart teff grains from other wild grains by looking at its shape and size, since we would assume the plump, round seeds would indicate selectiveness for more uniform size in the yield.
Nutritional Value and Consumption
Teff is consumed for its small seeds and mainly consumed in the form of teff flour to make the Ethiopian dish Injera. Teff can also be prepared in a porridge and used to brew alcohol. Teff straw is used for livestock forage feed. Teff itself is 80% Carbs, 11% protein and 3% fat. Teff is also a great source for dietary fiber, amino acids, iron, calcium and potassium. The consumption of Teff is linked to diabetes prevention for its high fiber content in controlling blood sugar levels. Teff by itself has a sweet, nutty flavor. Teff flour is almost always a whole-grain flour due to how small the grains are. Injera made from teff is one of the most significant components of Ethiopian and Eritrean food as it serves as both a platter and a utensil. Injera is a fermented sour spongy flatbread, resembling a pancake that is not turned before the front facing side is fully cooked due to the many small holes. Injera can also be incorporated as an ingredient in some stews. Stews and pulses are the main dishes of Ethipian and Eritrean cuisine, and they are usually served on top of injera, with additional rolls of injera provided to scoop the stews. The sponge-like texture of tef injera allows in to absorb and enhance the flavors of these stews.
Domestication and Cultivation
Teff is believed to be one of the earliest plants to ever be domesticated. As previously stated, the sites at Ona Nagast have given us an idea of how long teff has been in use for. However, there is not much else that is known about its domestication history. It is believed that plump, rounder seeds were selected for, as well as more spikes and a stronger resistance to lodging to increase yields. Since mechanization for harvests has been kept to a minimum for several reasons, teff is not grown in large amounts outside of the Horn of Africa.

Teff can be plated during late spring/rainy seasons, and late plantings are usually the norm to properly till the soil and prevent teff seedlings from being outcompeted by weeds. Seed beds must be firm, similar to that of other grasses. Seeding rates can range from 4.5 to 9.0 kg/ha, and should be seeded at about 12-15 mm deep. Usually, rows are best, as they allow for people to come between the plants to pull out weeds. Lodging is the biggest problem when planting grasses like teff, and therefore nitrogen and phosphorus are used to fertilize the soil to prevent excessive lodging. Harvesting the grain also poses some challenges due to the small size of the seed. Combine delivery systems must be checked to prevent seeds from being missed during the harvest, and there are also issues with preventing dust from being gathered with the harvested seeds in the combine and grain hopper. Unfortunately small dirt particles are very difficult to remove from the teff due to its small size. Average yields in Ethiopia are about 2 tonnes/ha. Harvests in Ethiopia usually are done with sickles, and animals walking on the harvest are used to thresh the crop.
Human Experience and Other Uses
Teff has been a staple crop in East Africa for thousands of years. So much so that Teff growing accounts for 31% of Landmass use in Ethiopia. Teff is a unique grass in that it is entirely absent from the rest of the world outside of the Horn of Africa. It is believed to have been domesticated before times of recorded history, meaning that its an ancient grain that has grown and maintained itself as a staple of the Northern African culture and diet. In fact, teff makes up two thirds of a person’s daily protein intake in Ethiopia. It is also important to note that it is used for fodder and straw to feed livestock, which were historically used in the harvesting of teff and along with other sources of starch and proteins, make up the remainder of the diet East Africans have depended on since ancient times.Teff grass can even be used to build shelters when mixed with mud, as the plaster hardens into thick slabs that protect from heat and humidity. Teff grass plaster has been used to build grain storage with little to no cost to the farmers.
References
D'Andrea , A. C. (2008, December). T'ef (Eragrostis tef) in ancient agricultural systems of ... - JSTOR. T'ef (Eragrostis tef) in Ancient Agricultural Systems of Highland Ethiopia. Retrieved June 1, 2022, from https://www.jstor.org/stable/40390389

Liu, K., Wang, R., Guo, X.-X., Zhang, X.-J., Qu, X.-J., & Fan, S.-J. (2021, January 6). Comparative and phylogenetic analysis of complete chloroplast genomes in Eragrostideae (Chloridoideae, Poaceae). MDPI. Retrieved from https://www.mdpi.com/2223-7747/10/1/109/htm
National Research Council. (1996). Lost Crops of Africa: Volume I: Grains. NationalAcademies. Retrieved from https://nap.nationalacademies.org/read/2305/chapter/15#230
Petruzzello, M. (2016, September 6). Teff. Britannica. Retrieved from https://www.britannica.com/plant/teff
Piccinin, D., & Woldetatios, T. (2020, February 25). More about Ethiopian food: Teff. EthnoMed. Retrieved from https://ethnomed.org/resource/more-about-ethiopian-food-teff/
Stallknecht, G. F. (1998, February 24). Crop Fact Sheet: Teff. Purdue University. Retrieved from https://hort.purdue.edu/newcrop/CropFactSheets/teff.html#Origin