Doğal Tetraploid Trifolium pratense L.’ de Suspensor Hücrelerinin Ultrastrüktürü

Year 2013, Volume: 8 Issue: 1, 1 - 8, 10.06.2013

Hatice Büyükkartal

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

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