Table of Contents
Ram, R., D. Catlin, J. Romero, and C. Cowley. 1990. Sesame: New approaches
for crop improvement. p. 225-228. In: J. Janick and J.E. Simon (eds.),
Advances in new crops. Timber Press, Portland, OR.
Sesame: New Approaches for Crop Improvement*
Raghav Ram, David Catlin, Juan Romero, and Craig Cowley
- PLANT BREEDING
- NEW APPROACHES FOR CROP IMPROVEMENT
- Table 1
- Fig. 1
Sesame (Sesamum indicum L.), thought to have originated in Africa, is
considered to be the oldest oilseed crop known to man and is now grown in many
parts of the world including the U.S. Sesame seed is an important source of
edible oil and is also widely used as a spice. The seed contains 50-60% oil
which has excellent stability due to the presence of natural antioxidants such
as sesamolin, sesamin and sesamol (Brar and Ahuja 1979). The fatty acid
composition of sesame oil varies considerably among the different cultivars
worldwide (Yermanos et al. 1972, Brar 1982). After oil extraction, the
remaining meal contains 35-50% protein, and is rich in tryptophan and
methionine. Seeds with hulls are rich in calcium (1.3%) and provide a valuable
source of minerals (Johnson et al. 1979). The addition of sesame to the high
lysine meal of soybean produces a well balanced animal feed.
Total world production of sesame in 1986 was 2.4 million metric tons, 65% of
which was produced in Asia (FAO Production Yearbook 1987). The U.S. is the
largest importer of sesame, importing about 40,000 metric tons per year mostly
from Mexico. Almost all sesame consumed in the U.S. is as a spice for food
products such as hamburger buns and other bakery goods. Minor uses of sesame
oil include pharmaceutical and skin care products and as a synergist for
insecticides (Salunkhe and Desai 1986).
Although a major world oilseed crop, sesame is primarily grown by small farmers
in developing countries in the southern latitudes. Crop development programs
in these countries are either small or nonexistent, and little progress has
been made during the past 20 years. A revitalization of sesame research using
modern plant breeding knowledge and new technologies could be of great value in
improving the crop.
Sesame yields are highly variable depending upon the growing environment,
cultural practices, and cultivar. Worldwide yields averaged about 340 kg/ha in
1986; however, yields as high as 2,250 kg/ha have been obtained in test plots
in Texas (Brigham 1985). A major contributing factor to low yields in sesame
is that the seed capsules shatter causing a loss of large amounts of seed,
particularly when the crop is machine harvested. Sesaco Corporation in Yuma,
Arizona, has developed semi-indehiscent commercial cultivar with yields ranging
from 600-1600 kg/ha (Brigham 1987).
A panel of sesame experts recently met in Vienna under the auspices of the FAO
and summarized plant breeding objectives for sesame improvement (Ashri 1987).
These included improved seed retention in the capsule, increased oil content,
uniform maturity and disease resistance.
A considerable amount of mutation and plant breeding work has been undertaken
in several laboratories throughout the world. Mutation breeding has been
successful in producing generic lines with the determinate habit. Combining
the high-yield trait with the semi-indehiscence trait could prove advantageous
for developing a machine-harvested sesame crop.
An early maturing line with 3 seed capsules per axil was selected from a
composite population in California (Paul Brookhouzen, personal communication).
Preliminary tests at a field nursery in Minnesota showed encouraging yields,
thus demonstrating a potential for selection of lines suitable for a short
Several opportunities now exist for sesame improvement as a result of recent
developments in plant tissue culture and generic manipulation of crop plants.
Sesame plants can be regenerated from shoot apical meristems and hypocotyl
segments and grown to maturity in less than four months (Fig. 1A). Similar
reports of successful plant regeneration from hypocotyl segments have recently
been published (George et al. 1987). This provides an opportunity for generic
transformation using Agrobacterium as the vector.
Shoots regenerated via organogenesis from apical meristems and hypocotyl
segments involves little or no callus issue production and variability in the
progeny of regenerated plants is expected to be minimal. Thirty-nine seeds
from 12 regenerated plants were planted in the greenhouse. Seeds from these
second generation plants were analyzed and showed no major variation in fatty
acid composition (Table 1).
Tissue culture methods involving a callus phase or regeneration via somatic
embryogenesis are known to produce stable variants (Armstrong and Phillips
1988). We have successfully induced somatic embryos directly from the surface
of the zygotic embryos of sesame in culture. Somatic embryo induction in six
cultivars ('Aceitera', `Arawaca', `Turen', `Piritu', `Maporal' and `Inamar)
varied from 50 to 100%. A large number of plants can be regenerated using such
a system (Fig. 1B). To date, over 500 plants of five sesame genotypes have
been regenerated. Their progeny will be screened for variation in
characteristics such as seedling growth, vigor, placental thickness, capsule
dehiscence, seed size, seed dormancy, yield, oil content and oil quality.
Callus cultures derived from cotyledons and hypocotyl segments were induced to
produce embryos, although induction frequencies were low. Long-term callus
culture systems would be useful for in vitro selection studies involving
selective agents such as pathogenic fungal toxins, herbicides, and minerals.
To further enhance variability induced in tissue culture, embryogenic sesame
cultures were also subjected to in vitro mutagenesis during culture induction.
Several plants regenerated from these cultures showed morphological variations
such as stem fasciation and differences in vigor and branching. Progeny seed
will undergo further field evaluation and biochemical analysis.
Tissue culture methods can also be used to facilitate wide crosses using embryo
culture techniques. Although conventional hybrid crosses between cultivated
sesame and its wild relatives have been attempted (Nayar and Mehra 1970), in
most cases hybrids were difficult to produce. In preliminary studies, we
cultured zygotic embryos at various developmental stages, and plants were
regenerated from embryos obtained 15 days after pollination. Similar methods,
could be used to regenerate plants from embryos generated from wide hybrid
The technologies currently being developed at Sungene for sesame and other
oilseed crops, such as sunflower, rapeseed and cotton, offer great potential
for sesame improvement. An integrated approach combining cell biology,
molecular biology, biochemistry and plant breeding needs to be undertaken using
all available technological advancements.
Variants in biosynthetic pathways resulting in altered fatty acid profiles of
triglycerides in oil have been produced via tissue culture in sunflower and
rapeseed (Ram et al. 1988). Similar fatty acid changes can be expected in
sesame through somaclonal variation or direct gene introduction for specific
biochemical modifications. Increased amounts of oleic acid, long-chain fatty
acids and antioxidants should enhance the attractiveness of sesame for
specialty chemical markets.
- Armstrong, C.L., and R.L. Phillips. 1988. Genetic and cytogenetic variation in
plants regenerated from organogenic and friable, embryogenic tissue cultures of
Maize. Crop Sci. 28:363-369.
- Ashri, A. 1987. Report on FAO/IAEA expert consultation on breeding improved
sesame cultivars. Hebrew University, Israel.
- Brar, G.S. 1982. Variations and correlations in oil content and fatty acid
composition of sesame. Indian J. Agric. Sci. 52:434-439.
- Brar, G.S. and K.L. Ahuja. 1979. Sesame: its culture, genetics, breeding and
biochemistry p. 245-313. In: Malik, C.P. (ed.). Annu. Rev. of Plant Sci.
Kalyani publishers, New Delhi.
- Brigham, R.D. 1985. Status of sesame research and production in Texas and the
USA, p. 73-74. In: A. Ashri (ed.). Sesame and sallower: status and potentials.
Publ. 66. FAO, Rome.
- FAO Production Year Book. 1987. vol. 40. Food and Agriculture Organization of
the United Nations-Rome, p. 116.
- Brigham, R.D. 1987. Status of sesame (Sesamum indicum L.) breeding in
the USA. Agronomy abstracts. 1987 Annual meetings, p. 57. Am. Soc. Agron.
Madison, WI. (Abstr.)
- George, L., V.A. Bapat, and P.S. Rao. 1987. In vitro multiplication of sesame
(Sesamum indicum) through tissue culture. Ann. Bot. 60:17-21.
- Johnson, L.A., T.M. Suleiman, and E.W. Lusas. 1979. Sesame protein: A review
and prospectus J. Amer. Oil Chem. Soc. 56:463-468.
- Nayar, N.M. and K.L. Mehra. 1970. Sesame: Its uses; botany, cytogenetics, and
origin. Econ. Bot. 24:20-31.
- Ram, R., T.J. Andreasen, A. Miller, and D.R. McGee. 1988. Biotechnology for
Brassica and Helianthus improvement, p. 65-71. In: Applewhite,
T.H., (ed.) Proceedings World Conference on Biotechnology for Fats and Oils
Industry. Amer. Oil Chem. Soc., USA.
- Salunkhe, D.K. and B.B. Desai. 1986. Post-Harvest biotechnology of oilseeds.
CRC Press, Boca Raton, Florida. p. 105-117.
- Yermanos, D.M., S. Hemstreet, W. Saeeb, and C.K. Huszar. 1972. Oil content and
composition of the seed in the world collection of sesame introductions. J.
Amer. Oil Chem. Soc. 49:20-23.
*Acknowledgments. The authors wish to thank Ms. Alexi Miller for critical
review of the manuscript, Ms. Tammy Branch for graphics preparation and Ms.
Leona Tarrice for word processing.
Table 1. Fatty acid composition of oil in R, seeds (second selfed
generation from tissue-cultured regenerants) of sesame.
||Fig. 1. Sesame plant regeneration in tissue culture. A. Shoot proliferation from hypocotyl segments. B. Plants regenerated from zygotic immature embryos.
Last update August 27, 1997