Doğal Tetraploid Trifolium pratense L.’ de Suspensor Hücrelerinin Ultrastrüktürü

Abstract

Bu makalede, doğal tetraploid Trifolium pratense L. ‘nin embriyogenez sırasında embriyonik organın sitolojisi ve gelişimi üzerine olan gözlemleri kapsar. Doğal tetraploid Trifolium pratense (Elçi çayırüçgülü)’de zigotun ilk bölünmesi enine veya eğiktir ve eşit olmayan iki hücre oluşur. Bazal hücre terminal hücreden büyüktür. Daha küçük olan terminal hücre bölünerek embriyoyu oluşturur. Büyük bazal hücre ise vakuollü suspensoru meydana getirir. Proembriyo evresinde terminal hücrenin çekirdeği uzar ve hücrede daha büyük bir alanı işgal eder. Bazal hücre çekirdeğinde elektronca yoğun bölgeler mevcuttur. Bu bitkide suspensor hücreleri embriyogenezin erken evrelerinde oldukça hızlı gelişir. Embriyo gelişiminin erken küresel evresinde 4-8 hücrelidir. Suspensor hücrelerinin sitoplazmasında küçük vakuoller, lipid ve protein cisimcikleri ile ribozom, mitokondri ve ER bulunduğu gözlenmiştir. Embriyo gelişiminin küresel evresinde suspensor hücrelerinin sayısı artar. Embriyogenez süresince suspensor hücreleri küçük vakuollü ve elektronca az yoğundur ve embriyo hücrelerine oranla daha az ribozom içerirler. Embriyo gelişiminin kotiledon şekilli evresinde dejenere olan suspensor hücreleri olgun tohumlarda gözlenmemiştir.

Keywords

• Trifolium pratense,suspensor hücreleri,embriyo gelişimi,ince yapı

Ultrastructure of the Suspensor Cells in the Natural Tetraploid Trifolium pratense L. (Fabaceae)

Abstract

This paper reports observations of the development and cytology of this embryonic organ in the natural tetraploid Trifolium pratense L. during embryogenesis. In the natural tetraploid Trifolium pratense (var. Elçi) the division of the zygote occurs in the transverse or oblique direction, resulting in the formation of two unequal cells. The basal cell is a larger than the terminal cell. The smaller terminal cell divides further and give rise to the embryo proper. The larger basal cell develops into vacuolated suspensor. In proembryo stage, the terminal cell nucleus becomes elongated, and occupies a large part of the cell. The basal cell nucleus which contains several electron-dense regions. The growth rate of the suspensor cells is very rapid during earlier stages of embryogenesis. In the early globular embryo stage, the suspensor consists of four or six cells and contains mitochondria, ER, ribosomes, lipid droplets, small protein bodies and vacuoles. In the late globular embryo stage, the suspensor cell expanded like massive structure. During embryogenesis, the suspensor cells are usually filled with small vacuoles are less electron-dense, and fewer ribosomes than the adjoining embryo cells. The suspensor undergoes at the cotyledone stage embryo and is not present in the mature seeds

Keywords

• Trifolium pratense, suspensor cells, embryo development, ultrastructure

References

1. Yeung E.C., Meinke D.W., 1993. Embryogenesis in angiosperms: development of the suspensor, Plant Cell, 5: 1371–1381.
2. Natesh S., Rau M.A., 1984. The embryo. pp. 377–443 In: Johri BM [ed.], Embryology of Angiosperms, Springer, Berlin, Heidelberg, New York, Tokyo.
3. Maheshwarı P., 1950. An introduction to the embryology of Angiosperms. McGraw-Hill, New York.
4. Yeung E.C., 1980. Embryogeny of Phaseolus: The role of the suspensor, Zeitschrift für Pflanzenphysiologie, 96: 17–28.
5. Lersten N.R., 1983. Suspensors in Leguminosae, Botanical Review, 49: 233–257.
6. Bohdanowicz J., 1987. Alisma embryogenesis: the development and ultrastructure of the suspensor, Protoplasma, 137: 71-83.
7. Avanzi S., Cionini P.G., D’Amato F., 1970. Cytochemical and autoradiographic analyses on the embryosuspensor cells of Phaseolus coccineus L., Caryologia, 23: 605-638.
8. Kozieradzka-Kiszkurno M., Bohdanowicz J., 2006. Development and cytochemistry of the embryo suspensor in Sedum, Acta Biologica Cracoviensia Series Botanica, 48 (2): 67–72.

9. Sussex I., Clutter M., Walbot V., Brady T., 1973. Biosynthetic activity of the suspensor of Phaseolus coccineus L. Caryologia 25: 261-272.
10. Cremonini R., Cionini P.G., 1977. Extra DNA synthesis in embryo suspensor cells of Phaseolus coccineus L.,. Protoplasma, 91: 303-313.
11. Singh A.P., Bhalla P.L., Malik C.P., 1980. Activity of some hydrolytic enzymes in autolysis of the embryo suspensor in Tropaeolum majus L., Annals of Botany, 45: 523–527.
12. Ceccarelli N., Lorenzl R., Alpi A., 1981. Gibberellin biosynthesis in Phaseolus coccineus suspensor, Zeitschrift für Pflanzenphysiologie, 102: 37-44.
13. Piaggesi A., Picciarelli P., Lorenzi R., Alpi A., 1989. Gibberellins in embryo-suspensor of Phaseolus coccineus L. seeds at the heart stage of embryo development, Plant Physiology, 91: 362-366.
14. Nikitcheva Z.I., 2006. Suspensor. pp. 198–202, In: Embryology of flowering plants, (Eds.: Batygina T.B.), vol. 2. New Hampshire: Science Publishers, p. 786.
15. Yeung E.C., Zee X.Y., Ye X.Y., 2006. Suspensor functions. pp. 208-212, In: Embryology of flowering plants, (Eds.: Batygina T.B.), vol. 2. New Hampshire: Science Publishers, p. 786.
16. Mua X., BiaoJin C., Teng N., 2010. Studies On the early development of zygotic and synergid embryo and endosperm in polyembryonic rice Ap III., Flora, 205: 404–410.
17. D'Amato, F., 1984. Role of polyploidy in reproductive organs and tissues, pp. 519–566. In: Embryology of Angiosperms, (Eds.: Johri B.M.), Springer, Berlin, Heidelberg, New York, Tokyo.
18. Łuszczek D., Świerczynska Ji., Bohdanowicz J., 2000. Polyploidization in the suspensor of Triglochin maritimum L. (Juncaginaceae), Acta Biologica Cracoviensia Series Botanica, 42: 131–137.
19. Elçi Ş., 1982. The utilization of genetic resource in fodder crop breeding, Eucarpia Fodder Crop Section 13-16 September, Aberystwyth UK.
20. Luft J.H.,1961. Improvements in epoxy resin embedding methods, Journal of Biophysical and Biochemical Cytology, 9: 409-414.
21. Algan G., Bakar H.N., 1996. Light and electron microscopic examination of the embryo and endosperm development in the natural tetraploid Trifolium pratense L., Israel Journal of Plant Sciences,44 (3): 273-288.
22. Walbot V., Brady T., Clutter M., Sussex I.M., 1972. Macromolecular synthesis during plant embryogeny: Rates of RNA synthesis in Phaseolus coccineus L. embryos and suspensors, Developmental Biology, 29: 104-1 11.
23. Clutter M. Brady T., Walbot V., Sussex I.M., 1974. Macromolecular synhesis in diploid and polytene cells in bean embryos, Journal of Cell Bıology, 63: 1097-1102.
24. Newcomb W., Fowke L.C., 1974. Stellaria media embryogenesis: The development and ultrastructure of the suspensor, Canadıan Journal of Botany, 52: 607-614.
25. Gunning B.E.S., Pate J.S., 1974. Transfer cells. pp. 441-480, In.: In Dynamic Aspects of Plant Ultrastructure, (Eds.: Robards A.W.), London: McGraw-Hill, p. 546.
26. Raghavan V., 1986. Embryogenesis in angiosperms. Cambridge University Press, UK, p. 316.
27. Schwartz B.W., Vernon D.M., Meinke D.W., 1997. Development of the suspensor: differentiation, communication, and programmed cell death during plant embryogenesis, pp. 53–72. In: Cellular and Molecular Biology of Plant Seed Development, (Eds.: Larkins B.A., Vasil I.K.) Kluwer Academic Publishers, p. 648.
28. Giuliani C., Consonni G., Gavazzi G., Colombo M., Dolfini S., 2002. Programmed cell death during embryogenesis in maize, Annals of Botany,90: 287-292.
29. Kuriyama H., Fukuda H., 2002. Developmental programmed cell death in Plants, Current Opinion in Plant Biology, 5: 568-573.