|Fenugreek Seedlings (Source: Saikat Basu, own work)|
Fenugreek (Trigonella) is the oldest medicinal plant in the world. Most popular species of this genus is Trigonella foenum-graecum, where the term “foenum-graecum” means ‘Greek hay’ pointing to its use as a forage crop in the past, fenugreek is grown mainly as a spice crop in the recent times. The plant is believed to be native to the Mediterranean region1-6. There are several controversies regarding the origin of the fenugreek plant for which no proper theory as to the ancestry of this plant could be laid down till date. Similar discrepancies have crept up about the total number of species of fenugreek available in the world. Linnaeus suggested that as many as 260 different varieties of fenugreek exist. But till now, only 18 species of fenugreek have been traced and only few are valid, such as T. anguina, T. arabica, T. caerulea, T. corniculata, T. cretica, T. foenum-graecum, T. gladiata, T. procumbens. Indigenous species of fenugreek are found in parts of Asia, Africa, Europe and Australia5.
Fenugreek is an annual, dicotyledonous plant belonging to the subfamily Papilionaceae under the family Fabaceae. The plant is characterized with trifoliate leaves, white papilionaceous flowers, roots bearing conspicuous root nodules and hard textured golden yellow seeds. The flowering shoots are of two types: the common variety bearing axillary flowers and the other variety termed ‘blind shoots’ bearing both axillary and terminal flowers1-6.
Breeding and Agronomy: Due to the recent surge in forage crop industry, several modern technologies are coming up to improve breeding of forage plants. And fenugreek, being a forage crop too, is no exception. Tissue culture and genetic engineering, gene delivery services and gene expression study are among them. All these techniques are carried out for the purpose of producing gene mutations in the embryo of the plants in order to bring about desired changes in the future generations1-8. Majority of fenugreek plants are self-pollinated. So artificial breeding among these plants becomes a problem. Hence, mutation breeding technique comes as a good solution. Rise in the demand of fenugreek as a forage crop occurred due to its several properties being comparable to alfalfa plant, as revealed by different studies conducted over the years. In vitro dry matter disappearance and crude protein level has been found to be higher than alfalfa, while in vitro gas production and volatile fatty acid content are almost similar. Reasonably high yield of forage is seen in semi-arid regions. Moreover, the phytochemicals of fenugreek reduces the need for synthetic steroids in the cattle. All these forage friendly properties of fenugreek have led to the increase in the global market for the plant 2-5, 10,11.
The first successful attempt in mutation breeding has been though the application of EMS (Ethyl methane sulfonates) in North America. The technique has produced plants with high yield and improved quality of seeds1-6,10-13. The EMS mediated mutation breeding study was carried out with the aim of overcoming two principal inconveniences seen in most fenugreek plants. They are indeterminate growth habit and late maturity. This delayed maturity occurs due to apical dominance, late filling of pods and seed maturity in the lower parts of the plants. For this purpose, the Tristar Fenugreek plant, a forage cultivar of North America was selected as it possesses both of the above two characteristics. The plant seeds were treated with gradually increasing concentrations of EMS (10-300 mM) for a period of 2-24 hours and tested for several generations. It was seen that with the gradual rise in EMS concentration, the rate of failure of plant survival diminished in the successive generations. Also, this survival pattern was affected by the duration of treatment with EMS under each concentration of the chemical i.e. from 2-24 hours. Thus the seeds treated with 300 mM EMS for 24 hours produced the highest number of lethal mutants10,11. But this variant of fenugreek, called the Tristar fenugreek, has a slower growth rate under adverse environmental conditions. So a study was conducted with five different genotypes of fenugreek to note the influence of environment and its interaction with genotype on the growth rates of the plants in Western Canada. It was seen that the Tristar variant had a high seed yield but a poor seed size, as compared to their respective mean values2-4,8-11. Addition of phosphate rich fertilizers in optimum amounts to phosphate deficient soils also boosted up the growth of fenugreek plants. But, no effect was observed in soils already rich in phosphorus9. Fenugreek plant possesses nitrogen fixing ability, thereby enriching the soil with nitrogen and simultaneously reducing the need for application of synthetic nitrogenous fertilizers. The plant is also quite suited to dry lands and hence lowers the cost for irrigation. Well drained loamy soil with a pH of 8-8.5 is preferred for cultivating these plants. Application of Gibberellic acid to the plant seeds prior to sowing improves the seed yield7-9. Pesticidal property of fenugreek is quite well known. Preparations from fenugreek leaves and seeds when mixed with stored grains have been found to keep pests like Tribolium castaneum at a distance. Molluscicidal action too has been seen with fenugreek extracts, especially to Indian fresh water snails like Lymnaea acuminata3,4.
Diseases of fenugreek: Several bacterial, viral, fungal and insect mediated infections of fenugreek are known to occur, resulting in considerable disruption of the forage production3,4,6,10-12. Of these, the two most prominent diseases are the Cercospora leaf spot and the powdery mildew caused by Erysiphe polygoni1-3,6,10,12. The Tristar cultivar is known to be particularly susceptible to the powdery mildew disease. The conditions that favor the occurrence of powdery mildew are 95-97 % relative humidity, overcast weather, temperature within 23-30 0C, annual precipitation of 350-400 mm with warmer days and cooler nights. This disease can be identified by the characteristic odor emitted by the infected plant leaves6,12. However, recent studies have shown that there are possibilities of resistance to this disease in certain fenugreek plants that express high levels of polyphenol oxidase, peroxidase and phenols1,5. Common viral disease includes the mosaic wilt, pea mosaic virus infection, soybean mosaic virus infection, etc. Pseudomonas syringae infection is a common bacterial infection. Insect mediated fenugreek infections include those by Lygus sp. and Adelphocoris sp6, 10,12.
Erysiphe polygoni DC conidiophore bearing
conidia containing conidiospores
(Source: Saikat Basu, own work)
|Healthy fenugreek dorsal (Source: Saikat Basu, own work)|
|Erysiphe infected dorsal (Source: Saikat Basu, own work)|
Medicinal, pharmaceutical and nutraceutical properties: Fenugreek has been used as a medicinal plant since time immemorial. It possesses a huge number and variety of chemical compounds that exert a wide range of biological functions. Some of the important chemicals are galactomannans, steroidal sapogenins (e.g. diosgenin, tigogenin, yamogenin, etc.), dihydroxysapogenins (e.g. gitogenin), spirostanol saponins (e.g. Graecunin B, C, D, E, G), triterpenoids, trigonelline, flavonoids (e.g. atroside, quercetin, etc.) and other1-8. Steroidal sapogenins are the sources for production of synthetic sex steroids and also for the treatment of hypercholesterolemia. Galactomannan is helpful in reducing the intake of glucose and other calorie rich foods, thus providing an effective control of blood glucose levels in diabetic patients. So does the amino acid isoleucine, but by acting in a different way: it regulates insulin release from the pancreatic cells. Besides these important properties, fenugreek leaf extracts have also been used to cure head lice (Pediculus humanus capitis) infection in human beings. The gum is industrially used as a food emulsifier and ice cream stabilizer1-5.
Another important medicinal property of fenugreek is its anti-oxidant nature. This was proved in a study conducted to determine the ability of fenugreek extracts to scavenge hydroxyl radicals and prevent lipid peroxidation1,2. That fenugreek possesses anti-microbial activity was proved from a study in which ethanol and aqueous extracts of fenugreek were found to be effective against certain enteric bacteria viz. Escherichia coli, Saccharomyces bayanus and Enterococcus fecalis. This study is perhaps the only most thoroughly done experiment to reveal anti-microbial action of fenugreek14. However, the amount and nature of these phytochemicals have been found to vary under different environmental conditions and also with the change in genotype. This phenomenon is called the genotype X environment interaction1-3,7-8.
The Foundation for Innovation in Medicine, USA has introduced a term recently, called ‘nutraceuticals’1-4,13. It refers to those products that are isolated and purified from foods sold in the form of medicine and is generally associated with food1-5. Fenugreek finds use in the global nutraceutical industry, with India having the maximum share of this international market1-4,11-13. Consumers of nutraceutical health products have increased in the past few years due to improvement of our understanding of the mode of action and health promoting actions of such plants and plant products. Also, the escalating costs of health care are compelling people to seek alternative medical strategies to improve health1-4,13. Several procedures have been used to increase the production of the phytochemicals in fenugreek. The traditional methods include mutation breeding and pure line selection13. Treatment of germinated plant seeds with solution of colchicines and DMSO (dimethyl sulfoxide) has produced plants with greater amount of oil7. Advanced technologies include tissue culture techniques and double haploid production13.
- Acharya, S. N., Acharya, K, Paul, S. and Basu, S. K. 2011. Variation in the antioxidant and anti-leukemic properties among different Western Canada grown fenugreek (Trigonella foenum-graecum L.) genotypes. Can. J Plant Sci. 91 (1): 99-105.
- Acharya, S. N., Basu, S. K., Datta Banik, S. and Prasad, R. 2010. Genotype X environment interactions and its impact on use of medicinal plants. The Open Nutra. J. 3: 47-54.
- Acharya, S. N., Thomas, J. E. and Basu, S. K. 2006a. Fenugreek: an “old world” crop for the “new world”. Biodiversity. 7(3&4): 27-30.
- Acharya, S. N., Thomas, J. E. and Basu, S. K. 2008a. Fenugreek (Trigonella foenum-graecum L.) an alternative crop for semiarid regions of North America. Crop Sci. 48: 841-853.
- Basu, S. K. and Prasad, R. 2011. Trends in new technological approaches for forage improvement. Aust J Agric Engg 2(6): 176-185.
- Basu, S. K., Acharya, S. N. and Thomas, J. E. 2006b. A report on powdery mildew infestations caused by Erysiphe polygoni D.C. in North America grown fenugreek. J. Mycopathol. Res. 44(2):253-256.
- Basu, S. K., Acharya, S. N. and Thomas, J. E. 2007a. Colchicine treatment produces genetic improvement in fenugreek seed size and yield. Proc. Multi. Grad. Res. Conf. 1(1): 37-43.
- Basu, S. K., Acharya, S. N. and Thomas, J. E. 2007b. Foliar spray to improve fenugreek seed yield and reduce maturity duration. Proc. Multi. Grad. Res. Conf. 1(1):44-50.
- Basu, S. K., Acharya, S. N. and Thomas, J. E. 2008b. Application of phosphate fertilizer and harvest management for improving fenugreek (Trigonella foenum-graecum L.) seed and forage yield in a dark brown soil zone of Canada. KMITL Sci. & Tech. J. 8(1):1-7.
- Basu, S. K., Acharya, S. N. and Thomas, J. E. 2008c. Genetic improvement of fenugreek (Trigonella foenum-graecum L.) through EMS induced mutation breeding for higher seed yield under prairie conditions of western Canada. Euphytica.160:249-258.
- Basu, S. K., Acharya, S. N., Bandara, M. S., Friebel, D. and Thomas, J. E. 2009. Effects of genotype and environment on seed and forage yield in fenugreek (Trigonella foenum-graecum L.) grown in western Canada. Aust. J. Crop Sci. 3(6): 305-314.
- Basu, S. K., Acharya, S. N., Cárcamo, H. A., and Thomas, J. E. 2006c. Study on the potential insect pests of fenugreek (Trigonella foenum-graecum L.) in North America with particular emphasis on the western flower thrips (Frankliniella occidentalis Pergande) in the greenhouse and plant bugs (Lygus and Adelphocoris, Miridae, Hemiptera) in the field. J. Environ. & Sociobiol. 3(1):1-7.
- Basu, S. K., Thomas, J. E. and Acharya, S. N. 2007c. Prospects for growth in global nutraceutical and functional food markets: a Canadian perspective. Aust. J. Basic Appl. Sci. 1(4):637-649.
- Thomas, J. E., Basu, S. K. and Acharya, S. N. 2006d. Identification of Trigonella accessions which lack antimicrobial activity and are suitable for forage development. Can. J. Plant Sci. 86(3):727-7