Aspectos da Reprodução em Brachiaria brizantha cv. Marandu

Alves, Eliseu

doi:10.1590/s0102-33062001000200019

Cited by 2 publications

(6 citation statements)

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“…The presence of nuclei inside the degenerated synergid observed in B. decumbens was also reported in vivo for B. brizantha cv. Marandu (Alves 2000;Alves et al 2001). Observation of this particular event demonstrates the normal method of transport in an in vitro pollination system.…”

Section: Discussionmentioning

confidence: 78%

“…In some accessions of Brachiaria used, pollen development was normal but in most of accessions development was hampered by lethality in the microspore stage, especially in apomicts. It is known that Brachiaria apomictic pollen has a higher level of abortion compared with the sexual pollen (Ngendahayo 1988;Dusi and Willemse 1999b;Alves 2000). In an earlier study during the period from February to June in Brazil, B. brizantha sexual BS1 viability was higher (87-90%) and more consistent than in apomictic B. brizantha cv.…”

Section: Discussionmentioning

confidence: 93%

“…In an earlier study during the period from February to June in Brazil, B. brizantha sexual BS1 viability was higher (87-90%) and more consistent than in apomictic B. brizantha cv. Marandu accession BRA000591 (35-72.5%); the latter displayed a maximum value in April, which is the peak of the flowering season (Alves 2000). The high level of degeneration observed in early microspores may point to a lethal effect from the preceding male meiosis.…”

Section: Discussionmentioning

confidence: 96%

“…Marandu, the degeneration of one of the synergids was associated with pollen tube discharge inside the embryo sac (Alves 2000;Alves et al 2001). It is hypothesized that the synergids could also be cells involved in the expression of gametophyticgametophytic incompatibility (Ngendahayo 1988).…”

Section: Discussionmentioning

confidence: 99%

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Toward in vitro fertilization in Brachiaria spp.

et al. 2010

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Brachiaria are forage grasses widely cultivated in tropical areas. In vitro pollination was applied to accessions of Brachiaria spp. by placing pollen of nondehiscent anthers on a solid medium near isolated ovaries. Viability and in vitro germination were tested in order to establish good conditions for pollen development. Comparing sexual to apomictic plants, apomictic pollen has more abortion after meiosis during the microspore stage and a lower viability and, of both types, only some plants have sufficient germination in a high sugar concentration. Using in vitro pollination with the sexual plant, the pollen tube penetrates into the nucellus and micropyle, but the embryo sac degenerates and collapses. In the apomictic B. decumbens, in vitro pollination leads to the transfer of the sperm nuclei into the egg cell and the central cell. The results are discussed according to normal fertilization and barriers in sexual and apomictic plants.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Toward in vitro fertilization in Brachiaria spp.

et al. 2010

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“…Architecture, number and distribution of the flowers, anthesis pattern and gametophyte development were as those in the self-fertile cv. Marandu (Nunes 1984;Alves 2000) and in other sexual and apomictic Brachiaria accessions (Clayton and Renvoize 1986). Alterations observed in the female organs, such as the presence of two hermaphrodite flowers within the same spikelet and the presence of multiple embryo sacs of Polygonum type within the same ovule, are interesting aspects of the reproductive development that cannot be related to low fertility.…”

Section: Discussionmentioning

confidence: 99%

Seed abortion in the sexual counterpart of Brachiaria brizantha apomicts (Poaceae)

2007

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Gametophytic organization, fertilization and reproductive success are described for the fertile diploid Brachiaria brizantha accession BRA-002747 which is being raised for use in Brachiaria breeding programs, as well as to understand and control of apomixis in this genus. The current paper reports on reproductive biology and analysis of seed set in field experiments during three consecutive years. Unsuccessful seed production in this plant is believed to correlate with early inbreeding depression, based on the reproductive features analyzed. Caryopsis development was observed using differential interference contrast microscopy with seed set determined by the number of self-and open-pollinated pistils that fully developed into viable seeds. Developing and mature female and male gametophytes were observed in the context of flower phenology, morphology and anthesis patterns. Pollen viability was determined by acetocarmine staining and by observation of germination in vivo, which was also used to observe pollen tube/pistil interaction. Although normal development was observed in floral structures, anthesis and gametophytes, seed set was low, with 2 and 6% in self-and open-pollination, respectively, producing seed. Variations observed in the female organs, such as the presence of a hermaphrodite flower in 50% of the inferior floscules and the presence of multiple embryo sacs of the Polygonum type within the same ovule in 15% of the pistils, are not related to low fertility. The majority of pollen grains are viable, in spite of the reduced number of pollen tubes within the style and ovary carpel, and a developing caryopsis was observed in 70% of self-pollinated pistils, indicating successful double fertilization from 2 days after anthesis (DAA). Nevertheless, abortion gradually increased from 2 until 7 DAA and remains elevated until 12 DAA, when caryopsis maturity is achieved. These data confirm low seed set in this accession and indicate that low fertility is not a consequence of abnormalities, either in the floral or gamete structures, or pollen tube rejection, but most likely a consequence of inbreeding depression.

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Aspectos da Reprodução em Brachiaria brizantha cv. Marandu

Abstract: Resumos impressos de acordo com os originais enviados pelas respectivas Coordenadorias de Pós-Graduação.

Cited by 2 publications

References 0 publications

Toward in vitro fertilization in Brachiaria spp.

Toward in vitro fertilization in Brachiaria spp.

Seed abortion in the sexual counterpart of Brachiaria brizantha apomicts (Poaceae)

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