Publication: Lathyrus Undulatus Boiss. anterlerinde gelişim ve programlı hücre ölümü üzerinde çalışmalar
Abstract
Lathyrus undulatus Boiss. ANTERLERİNDE GELİŞİM VE PROGRAMLI HÜCRE ÖLÜMÜ ÜZERİNDE ÇALIŞMALAR Bu çalışmada Lathyrus undulatus Boiss. anterlerinde gelişim ve anter çeper tabakalarında programlı hücre ölümü incelendi. Farklılaşmamış anter oval şekilli ve dört lopludur. Anter çeperi tek tabakalı epidermis, tek tabakalı endotesyum, bir veya iki tabakalı ara tabaka ve tapetumdan oluşur. Tapetum salgı tipindedir. Sitokimyasal analizler tapetum hücrelerinde çözünmeyen polisakkaritlerin, proteinlerin ve lipitlerin genç polen evresinde arttığını gösterdi. Polen ana hücrelerinde mayoz bölünme düzenlidir ve polen taneleri iki hücreli iken doğaya atılırlar. Normal anter gelişimi sırasında anter çeper tabakalarının ölümü yüksek yapılı bitkilerin çiçeklerinde görülen programlı hücre ölümünün bir örneğidir. L. undulatus anterlerinde meydana gelen hücre ölümünün yerini ve zamanını tanımlamak için ışık, floresan ve elektron mikroskobu yöntemleri, mayoz bölünmenin başı ile olgun polen evresi arasındaki çiçek tomurcuklarına uygulandı. Tapetum hücrelerindeki ilk programlı hücre ölümü işaretleri olan nukleus bozuklukları ve TUNEL pozitif reaksiyon genç polen evresinde gözlendi. Vakuollü polen evresinde programlı hücre ölümünün belirtileri baskın olarak arttı. Parçalanmanın sonuna kadar hücre ve nukleusta görülen belirtiler kromatinin nukleus zarının periferinde yoğunlaşması, nukleus zarının parçalanması ve kromatinin sitoplazmaya geçmesi, endoplazmik retikulum kanallarının artması ve şişmesi, lipoksigenaz aktivitesinin artması ve tonoplastın parçalanmasıdır. Tapetum otolizinin sonunda hücre organelleri parçalanır. Parçalanmadan sonra salgı ürünü olan hücresel kalıntılar polen çeperine nakledilir.
STUDIES ON THE DEVELOPMENT AND PROGRAMMED CELL DEATH IN THE ANTHERS OF Lathyrus undulatus Boiss. The presented study is intended for elucidation of anther development and programmed cell death in the anther walls of Lathyrus undulatus Boiss. The undifferentiated anther is ovoid-shaped and tetrasporangiated. The anther wall is composed of an epidermal layer, endotechial layer, one or two middle layers and tapetum. The tapetum is of glandular type. Cytochemical analysis showed that insoluble polysaccharides, proteins and lipids increased in tapetal cells at young microspore stage. The meiotic division of pollen mother cells is regular and pollen grains are 2-celled at the time of shedding. The death of the anther wall cells in normal anther development is an example of programmed cell death (PCD) in floral organs of higher plants. To characterize the spatial and temporal occurrence of PCD in L. undulatus anthers, light, fluorescence and electron microscopy methods were applied to the flower buds from meiosis to pollen release. The first hallmarks of PCD in the tapetal cells were observed at young microspore stage including nucleus disorder and TUNEL positive reaction. At vacuolated pollen stage, PCD hallmarks progressively increased. Diagnostic features of the whole cell and the nuclei were condensation of the chromatin at the periphery of the nuclear membrane, nuclear membrane rupture and efflux of the chromatin to the cytoplasm, increase and enlargement of the endoplasmic reticulum cisternae, increase of lipoxygenase activity and tonoplast rupture until the last stages of degeneration. The final stage of tapetal autolysis involves the disappearance of the cell organelles. After tapetal degeneration the remnants, acting as products of secretion, transform into pollen coat materials
STUDIES ON THE DEVELOPMENT AND PROGRAMMED CELL DEATH IN THE ANTHERS OF Lathyrus undulatus Boiss. The presented study is intended for elucidation of anther development and programmed cell death in the anther walls of Lathyrus undulatus Boiss. The undifferentiated anther is ovoid-shaped and tetrasporangiated. The anther wall is composed of an epidermal layer, endotechial layer, one or two middle layers and tapetum. The tapetum is of glandular type. Cytochemical analysis showed that insoluble polysaccharides, proteins and lipids increased in tapetal cells at young microspore stage. The meiotic division of pollen mother cells is regular and pollen grains are 2-celled at the time of shedding. The death of the anther wall cells in normal anther development is an example of programmed cell death (PCD) in floral organs of higher plants. To characterize the spatial and temporal occurrence of PCD in L. undulatus anthers, light, fluorescence and electron microscopy methods were applied to the flower buds from meiosis to pollen release. The first hallmarks of PCD in the tapetal cells were observed at young microspore stage including nucleus disorder and TUNEL positive reaction. At vacuolated pollen stage, PCD hallmarks progressively increased. Diagnostic features of the whole cell and the nuclei were condensation of the chromatin at the periphery of the nuclear membrane, nuclear membrane rupture and efflux of the chromatin to the cytoplasm, increase and enlargement of the endoplasmic reticulum cisternae, increase of lipoxygenase activity and tonoplast rupture until the last stages of degeneration. The final stage of tapetal autolysis involves the disappearance of the cell organelles. After tapetal degeneration the remnants, acting as products of secretion, transform into pollen coat materials