ABSTRACT
The objective of this study was to describe the pollen grain development in hermaphrodite papaya tree. The flower buds were collected at different stages of the development and the anthers were treated chemically for observation under optical and electronic transmission microscopes. The pollen grain development followed the normal pattern described for the Angiosperms. The pollen grain development was described from meiocyte to the mature pollen grain. In the microsporogenesis, the microspore mother cells or the meiocytes underwent meiosis giving rise to the tetrads that were enclosed by the calose. Later, the tetrads were released by the dissolution of the calose by calase activity and microspores underwent mitosis. Microgametogenesis was characterized by asymmetrical mitotic division of each microspore giving rise to bi-nucleate pollen grains. The structures similar to the plastids were found in the cytoplasm and close to the nucleus of the generative cell. Gradual degeneration was observed in the tapetum during the male gamete development.
Esta pesquisa descreve os estádios de formação do gameta masculino (grão de pólen) em mamoeiro. Para isto foram coletados botões florais em diferentes etapas de desenvolvimento e as anteras foram tratadas quimicamente para serem observadas ao microscópio óptico e eletrônico de transmissão. O desenvolvimento do grão de pólen seguiu o padrão normal para Angiospermas. Foram descritos os estádios de desenvolvimento do grão de pólen desde meiócitos ou células mães de micrósporos até o grão de pólen binucleado. Na microesporogênese, as células esporogênicas sofreram meiose dando origem as tétrades, com posterior liberação dos micrósporos da tétrade. A microgametogênese caracterizou-se, principalmente, pela divisão mitótica assimétrica de cada micrósporo originando grãos de pólen binucleados. Estruturas semelhantes a plastídios foram encontradas no citoplasma da célula generativa e agregados próximos ao núcleo da célula generativa. Observou-se degeneração gradativa das células do tapete no decorrer da formação do gameta.
ABSTRACT
Objetivou-se neste trabalho avaliar a influência da planta doadora de pólen sobre as características dos frutos produzidos na cultura do maracujazeiro-amarelo (Passiflora edulis f. falvicarpa). Neste contexto, um experimento foi conduzido, segundo o esquema de cruzamentos controlados. Empregaram-se 23 plantas "genitor masculino" e 103 plantas receptoras de pólen, perfazendo o total de 185 frutos avaliados segundo as características: peso, largura, comprimento, número de sementes e peso relativo de 100 sementes. A avaliação dessas características, segundo análise de variância multivariada (MANOVA), permitiu a verificação de efeitos significativos ("genitor masculino" e "fêmea hierarquizada a genitor masculino"). A partir das informações da MANOVA, construiu-se uma função discriminante, constituída pela primeira variável canônica baseada na matriz de soma de quadrados para a fonte de variação "genitor masculino" (Importância relativa = 58,10 por cento). A análise desta permitiu verificar elevado efeito da fonte de variação "genitor masculino" sobre as características dos frutos, cujos indivíduos foram agrupados univariamente em três grupos distintos. Tais resultados permitem concluir que tanto progenitores femininos como masculinos podem influenciar os resultados obtidos em esquemas de seleção massal.
This research was aiemd at evaluating the influence of the relactive pollination of pollen donor plant in obtaition higher fruits of yellow passion (Passiflora edulis f. falvicarpa). To do so, an experiment was conduced according to the controlled crosses, using 23 male plants and 103 pollen receptor plants. The total of fruits obtained was 185 units, that were evaluated according to the following traits: fruit weight, fruit diameter, fruit length, fruit seed number and relative weight of 100 seeds. The data were analyzed by using multivariate analysis (MANOVA). The discriminant function was constituted by the first canonic variable based on matrix of square sum of male (relative importance = 58.1). The discriminant function analysis permitted to verify high effect of male in relation to fruit traits, whose individuals were grouped in three distinct classes. The results indicate that female as well as male can influence the results obtained in mass selection.
ABSTRACT
The yellow passion fruit, Passiflora edulis f. flavicarpa, is one of the most important Brazilian fruit crops. It is an allogamous, diploid, and self-incompatible species. It has hermaphrodite, solitary flowers, located in the leaf axils and protected by leaf bracts. The flower has an androgynophore, which is a straight stalk supporting its reproductive parts. There are usually five anthers, located at the tip of each of the five filaments. The ovary is borne just above the filaments, at the top of the androgynophore; there are three styles that are united at their base, and at the top there are three stigmas. The objective of this research was to observe embryo sac development in yellow passion flowers. Ovaries at different stages of development were fixed in FAA (formalin, acetic acid and alcohol solution), hydrated, stained with Mayer's hemalum, and dehydrated. Ovules were cleared by using methyl salicylate, mounted on slides, and observed through a confocal scanning laser microscope. The yellow passion fruit ovule is bitegmic, crassinucellate, and anatropous, and its gametophyte development is of the Polygonum type. After meiosis, functional megaspores under go three successive mitotic divisions, resulting in an eight-nucleate megagametophyte: the egg apparatus at the micropylar end, two polar nuclei at the cell center, and three antipodals at the chalazal end. The egg apparatus is formed by an egg cell and two synergids, each with a filiform apparatus. The mature embryo sac has an egg cell, two synergids, two polar nuclei, and three antipodes, as has been described for most angiosperms