15 May 2000             

 

 

 

 

 

 

 

 

 

 

Role of ICARDA in Improving the Nutritional Quality and Yield Potential of Grasspea (Lathyrus sativus L.)

for Subsistence Farmers in Developing Countries

 

Ali M. Abd El-Moneim1, B. van Dorrestein1, M. Baum1 and W. Mulugeta2

 

Paper presented at the CGIAR- wide conference on Agriculture -Nutrition  Linkages,

Los Banos, The Philippines, 5-6 October, 1999

 

1International Center for Agricultural Research in the Dry Areas (ICARDA), P.O.Box 5466, Aleppo, Syria

2Ethiopian Agricultural Research Organization (EARO), Sheno Agricultural Research Center, P.O.Box 112, Debre Berhan, Ethiopia

 

 

 

 

 

 

 

 

 

 

 

ABSTRACT

                Lathyrus sativus (grasspea or chickling pea) is a popular food and feed crop in certain Asian and African countries such as Bangladesh, China, Ethiopia, India, Nepal, and Pakistan, because of its resistance to drought, flood and moderate salinity and because of its low input needs. When other crops fail under adverse climatic conditions, L. sativus could be the only available food source for the poor sections of the population and sometimes is a survival food during famine. Although seeds of L. sativus are tasty and protein-rich, They contain a high amount of free l-homoarginin, which can act as a precursor of lycine in higher animals. Over-consumption can cause a disease known as neurolathyrism, an irreversible paralysis of the lower limbs. The neurotoxic agent of this disease was identified as 3-N-oxalyl-L-2,3 diaminopropionic acid (ß-ODAP) or its synonym BOAA (ß-N-oxalyamino-L-alanin). The level of this compound in the dry seeds varies depending on genetic factors and environmental conditions.

 

The ability of L. sativus to provide economic yield under most adverse conditions has made it a popular crop in subsistence farming in many developing countries, and it offers a great potential for use in other parts of the world. In the West Asia and North Africa (WANA) region, under low rainfall (250-300 mm) conditions there is a tendency for increased monoculture of cereals such as barley. The incorporation of grasspea in the rotation can make the production system more sustainable by improving soil fertility and by breaking the disease and pest cycles.

 

The International Center for Agricultural Research in the Dry Areas (ICARDA) is placing special emphasis in improving this crop using the biodiversity available in the genetic resources. The objectives in the crop improvement program for this species are to improve its yield potential and nutritional quality through the reduction of its neurotoxin ß-ODAP content.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Some of these Ethiopian farmers and children may fall victim to lathyrism (paralysis of the leg muscles) when they have nothing else to eat but grasspea (field in the background) because the drought in the country has destroyed the other food crops.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A victim of lathyrism in Ethiopia.

 

 

 

 

 

 

 

 

 

 

 

 

 

Low-neurotoxin lines having 0.07 to 0.02% ß-ODAP were developed using conventional breeding methods and by developing somaclonal variants. These lines were distributed to national programs for testing under different environmental conditions. The low-neurotoxin strains could have a great impact on human and livestock nutrition in those resource-poor countries with vast areas of land under semi-arid conditions.

 

INTRODUCTION

                Lathyrus sativus L. or grasspea (Khesari in India and Bangladesh, guaya in Ethiopia, san li dow in China, pois carré in France) has been cultivated in South Asia and Ethiopia for over 2500 years (Bell, 1989) and is used as food and feed. It is a popular drought-tolerant crop food and feed in drought-prone areas of Africa and Asia (Khan et al., 1993 and Abdelmoneim et al., 1997). Its ability to provide economic yield under adverse conditions has made it a popular crop in subsistence farming in many developing countries and it offers great potential for use in marginal low-rainfall areas. Despite its tolerance to drought, grasspea is not affected by excessive rainfall and can be grown on land subject to flooding (Sinha, 1980). In Bangladesh, India, Nepal and Pakistan it is often broadcast into a standing rice crop where it flourishes on the residual moisture left after the rice has been harvested. It is a very hardy crop with penetrating root-system and can be grown on a wide range of soil types including very poor soils and heavy clays. This hardiness and its ability to fix atmospheric nitrogen make the crop one that seems designed to grow under adverse conditions.

 

For more than 100 million people in drought-prone areas of Asia and Africa, grasspea is a traditional popular crop, because of its easy cultivation, its relative resistance to drought, flood, moderate salinity and insect attack and its good yield of tasty protein-rich seeds, with about 30g per 100g edible seeds (Rutter and Percy, 1984 and Abdelmoneim et al., 1997). When other crops fail due to adverse conditions, grasspea can be the only available food source for the poorest section of the population, and sometimes a survival food in times of drought-induced famine.

 

Since grasspea is the cheapest food legume that most low-income families can afford, it is a common component of their traditional diet. Its seeds also contain a high amount of free l-homoarginin, which acts as precursor of lycin in human nutrition (Quereshi et al., 1977). These same seeds contain a neurotoxic non-protein aminoacid that can cause irreversible spastic paraparesis (paralysis) of the legs when it is consumed as a major portron of the diet over a 3 to 4 month period (Spencer and Schaumberg, 1983, Spencer et al., 1986). Recent outbreaks of famine in areas where grasspea could be a promising food crop for sustainable agriculture, have been followed by outbreaks of this upper motorneurone disease in epidemic proportions: Bangladesh in 1942-45 and in 1972-74 (Haque et al., 1991); China in 1973 (Liu and He, 1990); and Ethiopia in 1976-77 (Haimanat et al., 1990) and in 1997-98 (Lambien, personal communication).

 

The causative agent for neurolathyrism was confirmed as 3-(N-oxalyl)-L-2,3-diaminopropionic acid (ß-ODAP) or its synonym BOAA: B-N-oxalyl-L-alanin (Spencer et al., 1986 and Roy and Spencer, 1989), and the biochemical pathway of the toxin has been elucidated (Lambien et al., 1990 and Kuo and Lambien, 1991). However, no biological role of ß-ODAP in the plant has yet been proposed. The concentration of ß-ODAP in ripe seeds is very variable and is influenced by genetic and environmental factors (Lambien et al., 1993 and Abdelmoneim and Cocks, 1993). Water stress can double the toxin level, while salinity in the soil may reduce the toxin level in the seeds (Haque et al., 1992).

 

Despite grasspea’s obvious advantages, until recently relatively little effort has been made towards the improvement of this very hardy pulse crop. Indeed, the history of grasspea has been one in which its cultivation has been banned in many countries due to its toxicity. In spite of this, grasspea is still produced in significant quantities in many parts of the world. Improvement of this crop is now being addressed at ICARDA through its germplasm enhancement program.

 

 

ICARDA’s Role in Improving Nutritional Quality of Grasspea

                The International Center for Agricultural Research in the Dry Areas (ICARDA), which has a mandate for improve the productivity of dryland agriculture in the West Asia and North Africa (WANA) region, and more recently Central Asia and Caucasian Countries (CAC), is placing special emphasis on improving this crop. ICARDA has a breeding program for the improvement of cool-season food and forage legumes including grasspea. It also holds a rich collection of Lathyrus spp. germplasm (1883 accessions amongst them 1560 L. sativus) from different parts of the world. Using this precious resource, ICARDA is collaborating with national partners, to develop new grasspea lines with the objectives of improving its yield potential, adaptability and nutritional quality through reduction of its neurotoxin ß-ODAP to safe levels for human consumption and animal feed.

 

Since 1989-90 grasspea breeding program at ICARDA has aimed to reduce the neurotoxin ß-ODAP concentration by four approaches.

 

i.                     Germplasm evaluation

ii.                    Genetic detoxification (hybridization program)

iii.                  Exploitation of somaclonal variation (plant biotechnology)

iv.                 Soil micronutrients, Zn++ and Fe++

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Breeding new grasspea varieties with low neurotoxin content, safe for human consumption, is a major research project at ICARDA. Dr Ali Abd-El Moneim (right), responsible for this project, shows his new, low-neurotoxin grasspea material at ICARDA to Dr Paul Harding, Senior Research Advisor from the Department for International Development (DFID), U.K., which provides financial support for the project.

 

 

 

 

 

 

 

 

 

 

 

 

i.                    Germplasm Evaluation

An extensive screening program was initiated in 1989-90 for five years to explore the possibility of identifying toxin-free lines from germplasm of different origins. Results indicated that no accession of any Lathyrus species was ß-ODAP free, although in several lines the ß-ODAP content was low. This appears to be species related, since samples of L. cicera ranged from 0.03 to 0.22% with a mean of 0.16. L. sativus showed the highest range from 0.02 to 2.4% with a mean of 1.3%, while L. ochrus lines were highest in ß-ODAP ranging from 0.46 to 2.5% with a mean 1.4% in the ripe seeds (ICARDA, 1995). Four lines of L. sativus, viz, IFLLS 522 (Syria), IFFLS 588 (Cyprus), IFLLS 516 (Turkey) and IFLLS 563 (Turkey) were found to have a low ß-ODAP content in the seeds ranging from 0.02 to 0.07%. The level presumed safe for human consumption is <0.2% (Dahia, 1976).

 

Analysis of a large number of germplasm accessions of L.sativus revealed that samples from Bangladesh, Ethiopia, India, Nepal, and Pakistan are high in ß-ODAP content in the dry seeds in a range from 0.7 to 2.4%, whereas samples from North Africa, Syria, Turkey and Cyprus have significantly lower ß-ODAP, ranging from 0.02 to 1.2%.

 

ii.                  Genetic Detoxification (hybridization program)

Because the low neurotoxin lines have undesirable traits such as late flowering, susceptibility to insects and diseases and low yields, a hybridization program was initiated in 1991-92 with the objective of improving the yield potential, adaptability and nutritional quality by transferring low neurotoxin character to locally-adapted germplasm originating from grasspea-producing countries, e.g. Bangladesh, Ethiopia and Pakistan.

 

The ICARDA breeding program has made significant progress in selecting low-neurotoxin, high yielding lines and locally adapted. This work is carried out by a multidisciplinary team involving the breeder, pathologist, entomologist, biotechnologist and animal nutritionist. The major avenue of dissemination for the elite lines and segregated populations developed by the breeding program for selection under target environments is through the ICARDA International Legume Nursery Program.

 

Research activities with Ethiopian National Program commenced in the 1998-99 growing season. ICARDA supplied Ethiopian National Program with 100 improved lines of L. sativus. These lines were planted at Holetta Research Station for quarantine in 1997-98. In 1998-99, these lines were tested at two locations, Inewari and Molale. Eight high-yielding lines were selected at Inewari and 14 lines with high yield and cold tolerance were selected at Molale. Also nine lines were selected with 40% less ß-ODAP content than the checks (Adet local, Ginchi local, Inewari local and Molale local). ICARDA also supplied Ethiopian National Program with 120 samples of segregated populations of crosses between Ethiopian landraces and ICARDA’s low ß-ODAP lines for selection under Ethiopian conditions.

 

In 1999, the UK/CGIAR Competitive Research Facility (CRF) of the DFID (Department for International Development), is funding ICARDA to implement a project with Ethiopian Agricultural Research Organization (EARO) on “Improving Yield Potential and Quality of Grasspea (L. sativus): a Dependable Source of Protein for Subsistence Farmers in Ethiopia.” The project goals are alleviation of malnutrition, reduction of food shortages of dietary protein, and the increase of food quality and quantity for rural subsistence farm households in Ethiopia. This project will aid the promotion of grasspea as a safe source of dietary protein, thereby removing the stigma of neurolathyrism associated with this hardy and promising crop.

 

ICARDA is also expanding its activities in improving the nutritional quality of grasspea to some countries in Asia. For example, through the GRDC, Australia project ICARDA supplies Bangladesh Agricultural Research Institute with segregated populations for selection of lines with reduced concentration of ß-ODAP combined with disease and insect resistance. ICARDA is collaborating with the National Agricultural Research Institute, Islamabad, Pakistan in forage and fodder aspects of grasspea and in analytical aspects as well as development of high-yielding and reduced ß-ODAP adapted lines. For Nepal, target crosses between locally adapted lines and ICARDA’s low-neurotoxin lines were made and segregated populations were supplied for selection of low neurotoxin lines for local adaptation.

 

iii.        Exploitation of somaclonal variation
Biotechnological methods are being used to develop toxin-free lines of L. sativus. Recently, exploitation of somaclonal variation from landraces of Ethiopia and Pakistan has helped in isolating some somaclones differing in various characters with respect to flower colour, leaf size, seed colour, pod length and number of seeds per pod. Somaclones with low ß-ODAP less than 1% have been developed. These somaclones are being tested under different environments to study the stability of the neurotoxin content in ripe seeds.

 

iv.        Soil micronutrients Zn++ and Fe++

The neurotoxin of L. sativus is proposed to function as a carrier molecule for Zinc

ions (Lambien et al., 1994). Soils, depleted in micronutrients from flooding by monsoon rains (Indian subcontinent) or otherwise poor in available zinc and with high iron content (Ethiopia vertisols), may be responsible for the high level of neurotoxin in ripe seeds and subsequently for high incidence of human Lathyrism. This may explain why landraces originating from Bangladesh, Ethiopia, India, Nepal and Pakistan have higher ß-ODAP content than those of  North Africa, Turkey, Syria and Cyprus.

 

Zinc deficiency in the soil is an agronomic problem in Bangladesh, especially the monsoon-washed soils where grasspea is grown during the dry winter. Zinc deficiency in humans is also a widespread phenomenon in Bangladesh and Ethiopia leading to a number of symptoms like loss of hair, nail deformation, diarrhoea and mental retardation (Mannan and Rahim, 1988). ICARDA, through the DFID project and in collaboration with EARO, is placing more emphasis on the soil and other environmental conditions that can lead to a solution for neurolathyrism. More balanced fertilization of the soil may reduce toxin-increasing stress factors for the plants and at the same time increase productivity.

 

The Grasspea Improvement Program at ICARDA will continue to develop high-yielding, adapted lines containing very little or zero amount of the neurotoxin ß-ODAP. The feasibility of introgression of low-neurotoxin character from other closely related species like underground chickling (Lathyrus ciliolatus L.) will also be addressed. Our attempts to apply plant biotechnological methods to develop toxin-free lines of grasspea will continue. Somaclonal variation from landraces from Bangladesh, Ethiopia and Pakistan will  continue to be identified for low neurotoxin.

 

Development of low or zero neurotoxin lines will lead to making grasspea safe for human consumption and remove the stigma of neurolathyrism from this hardy crop.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

New grasspea genotypes with low neurotoxin content developed at ICARDA. This material is being shared with the countries where grasspea is grown and used for human consumption, for testing and adaptation as new varieties to replace the traditional varieties which have a high neurotoxin content.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ACKNOWLEDGEMENTS

ICARDA’s current collaboration with Ethiopia in improving the yield potential and quality of grasspea is sponsored by the Department for International Development (DFID) of the United Kingdom.

 
 

REFERENCES

Abdelmoneim, A.M. and P.S. Cocks. 1993. Adaptation and yield stability of selected lines of Lathyrus spp. under rainfed conditions in West Asia. Euphytica 66: 89-97.

 

Abdelmoneim, A.M., M.C. Saxena, A. El-Saleh and H. Nakkoul. The status of breeding grasspea (Lathyrus sativus L.) for improved yield and quality at ICARDA. In: “Lathyrus and Lathyrism, a decade of progress” (Eds: R. Tekle Haimanat and F. Lambien), University of Ghent, Belgium. 1997. pp. 81-83.

 

Bell, E.A. 1989. Lathyrus neurotoxin: history and overview. In: The Grasspea: Threat and promise. Proceedings of the International Network for the Improvement of Lathyrus sativus and Eradication of Lathyrism. Third World  Medical Research Foundation, New York, pp. 86-97.

 

Dahiya, B.S. 1976. Seed morphology as an indicator for low neurotoxin in Lathyrus sativus. Qual. Plant.-Pl. Fds.hum.Nut. 25:391-394.

 

Haimanat, R.T., Y. Kidane, E. Wuhib, A. Kalissa, T. Alemu, Z.A. Zein and S.P. Spencer. 1990. Lathyrism in rural North Western Ethiopia: A highly prevalent neurotoxic disorder. Int. J. Epidemiol. 19: 664-672.

 

Haque, A., M. Hossain, and G. Wouters. 1991. Epidemiological and clinical study of Lathyrism in Bangladesh: a preliminary report. Bangl. J. Neurosci. 7: 60-71.

 

 

Haque, R., M. Hussaina and F. Lambien. 1992. Effect of salinity on the neurotoxin ß-ODAP and other free aminoacids in Lathyrus sativus. Abstract, Second International Lathyrus/Lathyrism Conference in Ethiopia. p 21.

 

International Center for Agricultural Research in the Dry Areas (ICARDA), 1995: Germplasm Program (Legumes) Annual Report for 1995, pp. 167-169.

 

Khan, J.K., N. Kebede, Y.H. Kuo, F. Lambien, and A. De Bruyn. 1993. Analysis of the neurotoxin ß-ODAP and its a-isomer by pre-column derivatization with phenylisothiocyanate. Aanal. Biochem. 208: 237-240.

 

Kuo, Y.H., and F. Lambien. 1991. Biosynthesis of the neurotoxin B-N-oxalyl-a-B-diaminopropionic acid in callus tissue of Lathyrus sativus. Phytochemistry. 30: 3241-3244.

 

Lambien, F., G. Ogena, and H.Y. Kuo. 1990. B-Isoxazolinone-alanin is involved in the biosynthesis of the neurotoxin B-N-oxalyl-L-a-B-diaminopropionic acid. Phytochemistry 20: 3797-3796.

 

Lambien, F., J.K. Khan, H.Y. Kuo, C.C. Campell and I.C. Briggs. 1993. Toxins in seedlings of some varieties of grasspea (Lathyrus sativus). Nat. Toxins 1: 246-249.

 

Lambien, F., R. Haque, J.K. Khan, N. Kebede and Y.H. Kuo. 1994. From soil to brain: Zinc deficiency increases the neurotoxity of Lathyrus sativus and may affect the susceptibility for the motorneurone disease neurolathyrism. Toxicon 32: 461-466.

 

Liu, X. and F. He. 1990. Lathyrus sativus and Lathyrism in China. Lathyrus Lathyrism Newsletter. 2: 2.

 

Mannan, A. and A. Rahim. 1988. Zinc in nutrition, pp. 1-412. Dhaka: Bangladesh Agricultural Research Council.

 

Quereshi, M.Y., D.J. Pilbea,, C.V. Evans and E.A. Bell. 1977. The neurolathyrogen – amino-B-oxalylaminopropionic acid in legume seeds. Phytochemistry. 16: 477-479.

 

Rutter, J. and Percy, P. 1984. The pulse that maims. New Scientist 103: 22-23.

 

Roy, D.N., and S.P. Spencer. 1989. Lathyrogens. In: Toxicants of Plant Origin; Cheeke, P.R. Eds: CRC Press: Boca Raton, FL, 1989; Vol 111, pp. 169-201.

 

Sinha, S.K. 1980. Food Legumes: distribution, adaptability and biology of yield. Food and Agricultural Organization of the United Nations. FAO, Rome, Italy, pp. 156.

 

Spencer, P.S., and H.H. Schaumburg. 1983. Lathyrism: a neurotoxic disease. Neurobehav. Toxical. Teratol. 5: 625-629.

 

Spencer, P.S., A. Ludolph., M.P. Dawivedi, D.N. Roy, J. Hugon and H.H. Shaumburg. 1986.  Lathyrism evidence for role of the neuroexitatory amino acid BOAA. Lancet ii: 1066-1067.

 

 

 

 

 

 

 

 

 

 

 

 

Home