Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 10

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Gene pool variation of twenty varieties and breeding clones of Fragaria × ananassa, nine varieties and breeding lines of Fragaria vesca, and one new interspecific hybrid designated Fragaria × anavesca was analysed with three DNA marker systems. ISSR reactions with four primers produced 45 polymorphic markers. Similarly, RAPD analyses with three primers produced 26 markers and SSR method with three primer pairs revealed 28 different alleles. The total number of 99 polymorphic markers allowed distinguishing clearly a group of F. × ananassa genotypes from that of F. vesca genotypes with F. × anavesca in between of these two. RAPD markers proved to be more informative than ISSRs as 3 of 26 were specific to F. × ananassa only and one exclusively to F. vesca and F. × anavesca. Thus, the presumed hybrid nature of F. × anavesca was effectively confirmed by RAPD markers. Especially important was the 1100bp long PCR product of the B104 primer present in all F. vesca genotypes as well as in F. × anavesca but absent in F. × ananassa. Presence of F. vesca DNA in the hybrid F. × anavesca was additionally corroborated by the 223bp product of the UDF017 primer pair and the 185bp-long band generated with the UDF006 primer pair.
Megasporogenesis and female gametophyte development were investigated in ovules of the everbearing strawberry Fragaria × ananassa Duch. cv. Selva. Observations of thin sections revealed that ovule development starts from the formation of a nucellus and coincides in time with the beginning of receptacle overgrowth. The most characteristic feature during nucellus differentiation is the formation of a multicellular archesporium, beginning from at least two cells. Analysis of female gametophyte development indicated that in addition to the meiotic mode, female gametophytes develop by an apomeiotic mode of Antennaria type. Asynchronous development of female gametophytes of different origin occurs. The mature, eight-nucleate, seven-celled female gametophyte of meiotic origin is cylindrical and slightly curved. It occupies the central part of the nucellus. The egg apparatus, consisting of an egg cell and two synergids, is formed in the micropylar part of the female gametophyte; the opposite chalazal pole is occupied by antipodal cells. Besides the ovule in which only one seven-celled female gametophyte finally develops, ovules with a different number of cells were observed to initiate female gametophyte development. Some ovules contain a nucellus with a tetrad of linearly arranged megaspores surrounded by enlarged cells, each of which has the potential to develop into an apomictic female gametophyte. After degeneration of some post-meiotic cells or developmentally advanced female gametophytes, some of the chalazal cells initiated female gametophyte development.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.