Data/hora: 03/06/2024 10:52:43

Biblioteca(s): | Embrapa Soja.
Data corrente: | 20/12/2005
Data da última atualização: | 13/01/2006
Autoria: | PAGLIARINI, M. S.; BIONE, N. C. P.; BOLDRINI, K. R.; ALMEIDA, L. A.
Título: | A male-sterile mutation in soybean (Glycine max ) affecting chromosome arrangement in metaphase plate and cytokinesis.
Ano de publicação: | 2005
Fonte/Imprenta: | In: CONGRESSO BRASILEIRO DE GENÉTICA, 51., 2005, Águas de Lindóia. Resumos... Águas de Lindóia: SBG, 2005.
Descrição Física: | 1 CD-ROM.
Idioma: | Inglês
Notas: | Seção: Genética e Melhoramento - Resumos: Pdf.579.

Conteúdo:

In autogamous crop species with small flowers, such as soybean, manual cross-pollination to produce large quantities of hybrid seed is difficult and tedious. A number of molecular approaches have been used to study and regulate male sterility on various agricultural crops for F1 hybrid production. On the other hand, there are many plant species that display natural mutants that cause male sterility. Mutant nuclear genes (Mendelian inheritance) affecting male cell and organ development are designated ms genes. They
usually are recessive and typically expressed in specific sporophytic tissues at different stages. Several soybean male-sterile, female-sterile mutant lines have been described genetically and cytologically. Spontaneous male-sterile,female-fertile mutations have been identified in Brazilian lines of soybean breeding program developed by Embrapa Soybean. Sterile plants were identified, flower buds were for meiotic analysis and fixed in FAA (3 ethanol 95%:1 acetic acid:1 formaldehyde)for 24 h; transferred to 70%alcohol and stored at 4 0 C until use.Microsporocytes were prepared by squashing and stained with 0.5% acetic carmine.Nine male-sterile plants were cytologically analyzed.Pollen grains were stained with 0.5%acetic carmine and starch content was evaluated with lugol.In these male-sterile,female-fertile mutant bivalent arrangement at the metaphase plate and cytokinesis were affected.Until diakinesis, meiosis was perfectly normal with chromosome pairing as bivalents. From this phase, in several meiocytes, bivalents were not able to organize a single metaphase plate and remained scattered in the cytoplasm in a few or several groups. In these meiocytes, chromosomes segregated in both divisions giving rise to several micronuclei. However, the main cause of male sterility was the absence of cytokinesis after telophase II. Instead of the typical tetrads of microspores, four nucleate coenocytic microspores were formed. Typical tetrads of microspores were not detected in the present mutant.Instead of four haploid microspores, the meiotic products were replaced by four-nucleate coenocytic microspores.After pollen wall formation,and without suffering the pollen mitoses, the coenocytic microspores underwent gradual engorgement by starch,and entered into a progressive process of degeneration. Pollen sterility was complete. A ratio of a 3 male-fertile:1 male-sterile plant was found among self-pollinated progeny in line BR98-197H,where the mutation originally appeared and within segregating families. At least three male-sterile mutant lines identified in the Brazilian breeding
program and critically analyzed in the cytological context presented differential characteristics from those reported for a specific ms mutation. All of them were related to abnormal cytokinesis after telophase II, but always with some additional characteristics. Data suggest that some loci controlling male fertility in soybean tend more towards spontaneous mutations than others.

Categoria do assunto: | --
Registro original: | Embrapa Soja (CNPSO)
Exemplares: | CNPSO - (25855-1) - UPC - PL - -- - CD 0141 -  -  - DIS