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fCOMPORTAMENTO MEI6TICO E FERTILIDADE DO'P6LEN DE QUATRO CUL TIV ARES DE T ANGERINEIRA.Lia Rosane Rodrigyes. Maria Teresa Schifino Wittmann e A!!.!!

~; Lucia Cunha DornelJes. Faculdade de Agronornia da Universidade]:Federal do Rio Grande do Sui. Av. Bento Gon9a1ves, 7712, CEP\~91501-970, Porto Alegre, RS. Liarr@Vortex.ufrgs.br,

1: ~ Q~tro cultivares dipl6ides de j ,

CYTOGENETIC OAT A ABOUT SOME BRAZILIAN ACCESSI~NSOF PASPALUM. Luciene Regina Carraro. Patricia Matias de Freitas.Maria Suel): Pagliarini. Neide SilY!.DBC/UEM,Maringa-PR. Luiz AlbertoRocha Batista. CPPSE/EMBRAPA, Sao Carlos-Sr.

Although the cytogenetic studies on genus Paspalum have been startedsix decades ago, no more than 100 species have been evaluated. Severalspecies are economically important for forage, turf and ornamentalpurposes. The botanical composition of natural grassland communieties inBrazil shows a high contribution of species of this genus. Despite theenormous genetic variability existent, few forage options are available.About 215 accessions of somc species from different regions of Brazil areunder evaluation at the CPPSE/EMBRAPA The studies are directed at thechoise of accessions for intra- and interspecific hybridization. As polyploidis fr~uent in the genus and it is correlated \vith apomixis, the knowledge ofchromosome number is essential to the breeders. Young inflorescenceswere collected at CPPSE and fixed in Carnoy for 24 h and then transfelTedto 70% alcohol and stored under refrigeration. Microsporocytes wereprepared by squashing and staining with I % propionic carmine. Thechromosome number and the pairing relationships were determined indiakinesis. Twenty eight accessions belonging to 12 species and 20accessions not yet identified were analyzed. Among them, five presented2n=2x=20, fourty presented 2n=4x=40 and three presented 2n=6x=60chromosomes. The diploid accessions showed only bivalent associations atdiakinesis, while in the tetraploid the pairing relationships were irregularwith the chromosomes associating as univalents, bivalents andquadrivalents. The frequency of muitivalents in tetraploid accessionssuggest that the most of them are segmental allotetraploid. There was noevidence for autotetraploidy among the accessions analyzed. The resultsshowed tile among thc 48 accessions. only the five diploid present potentialfor breeding program.

Supported by: CNPq

tangcrincira Coram

, mei6tico c a fertilidade

Foram coletados botOes florais e flores em antesc dc

Os botaes t1orais com diametro medio de 3

r de p61en em todas as fuses da meioseoCa!, Montenegrina (Citrus deliciosa Tenore),

reticulata Blanco) e King (Co nobilis Lourciro)l microsporogenese bastante regular, com algumas

" ; irregular na anafase I. 0das cultivares atingiu vaJores elevados, majores

a gennina~Ao in vitro de gr30s de p61en no meio2 mM de Ca(N0))2 e 4%

; 16,03; 19,36; 11,50 e 11,85%, em

eKing, respectivamente. Os estudosas quatro cultivaTes possuem mdices elevados de

H.53 H.54

NUMBER AND MICROSPOROGENESIS IN SOME'CIES. Eleniza de Victor Adamowski Maria Suelx

JEM, Maring,j-PR. Luiz Alberto Rocha Batista.""

Paspalum, little or no

This paper

about chromosome number and meiotic

P. maritimum and P.

MACHO ESTERILIDADE EM SOJA GLYCINE MAX (L.)MERRIL: UMA MUTA~AO ESPONTANEA QUE CAUSADEGENERA~AO DA TETRADE DE MICR6sPOROS. Nil!.Q!1Cesar Pires Bione. Maria Suelv Pagliarini. DBC-UEM, Maringa-PR; .Leones Alves Almeida. CNPSo/ EMBRAPA, Londrina-PR.

Ocorrencia de muta~oes que causam macho esteri\idade e urnevento comurn em plantas superiores e particularmente utiI emprograrnas de melhoramento para obten~ao de variedades hI"bridas.Testes de fertiIidade de pOlen identificaram, ate 0 momento, cincomutantes espontaneos que causam macho esteri\idade no programade melhoramento de soja do CNPSo/EMBRAPA. 0 presente estudodedica-se a ava1ia~ao do comportamento meiotico na progenie docruzamento BR-16 x BR-83-l47, portadora de uma muta~ao capazde inviabilizar a produ~ao dog graos de polen. Botoes fIorais fixadosem FAA por 24 horas, transferidos para aIcool a 70% e conservadosem freezer ate 0 momento das anaIises, Coram preparados pelometodo conventional para estudos meioticos, utiIizando-se carmin Iacetico a ] % como corante. Os resultados das anaIises citologicasrevelaram que a muta~ao tern efeito a partir de telofase II tendo, as Irases anteriores, urn compOrtamento norn1al. Dentre asanormalidades encontradas destacam-se telofases IImorfologicamente irregulares e com aspecto degenerativo, ausencia rtotal de citocinese apas a telofase II ou citocinese incompleta oudesorientada, pontes citoplasmaticas entre rnicrosporos e alto indite Ide tetrades com diferentes niveis de degenera~ao. Estasirregularidades resultaram em aborto de rnicrosporos e,consequenternente, na nao produ~ao de polen. Embora vanosmutantes rneioticos que causam macho esterilidade tenham sidodescritos em linhas americanas de soja, nenhum deles apresenta asmesmas caracteristicas do mutante aqui descrito.Auxilio financeiro: CAPES.

squashing and stained with 1 % propionic carmine., .' was determined in diakinesis. All accessions of P.presented (2n=2x=20) chromosomes, with 10 bivalents atshowing onc or two terminal chiasmata. Although these

.chromosome behavior at

associating predominantly as bivalents.quadrivalents were observed in these

usc in intra- and intcrspecific crosses.

173