Neiva Izabel Pierozzi

Characterization of somatic chromosomes of two diploid species of Coffea L. with acetic orcein and C-band techniques

Abstract Two diploid (2n=22 chromosomes) and self-incompatible coffee species, Coffea canephora Pierre ex Froehner and C. dewevrei De Wild, et Th. Dur., were subjected to 2% acetic orcein and C- banding techniques with the purpose of mitotic chromosome characterizations. Karyological analysis were done in root cell chromosomes. These two diploid species of coffee could be distinguished mainly by some chromosome absolute (u,m) and relative (%) lenght mean values. In both species chromosome 5, 10 and 11 were metacentrics and the others were submetacentries; chromosomes 1 and 3 had secondary constriction beside centromere. The data suggested chromosome 3 had the NOR. Haploid karyotype formula was 1M + 2m + 7sm + lsms for C. canephora, and 3m + 7sm + lsms for C. dewevrei. Total karyotype length mean values were 16.97 ± 0.95u,m for C. canephora and 15.60± l.ll|imfor C. dewev rei and the difference was not significant. C-banded karyotypes were very similar in both species with prevailing centromeric/pericentrom...

Application of C-banding in two Arachis wild species, Arachis Pintoi Krapov. and W.C. Gregory and A. villosulicarpa Hoehne to mitotic chromosome analyses

Abstract Two wild diploid (2n. = 20 chromosomes) and self-pollinating Arachis species, Arachis Pintoi Krapov and W.C.Gregory and A. villosulicarpa Hoehne were submmited to C-band technique to karyotype analyses. Root tips were employed in the analyses. Morphometric data chose that chromosome lengths varied from 3.12 in A. villosulicarpa to 1.45 in A. Pintoi. Karyotype formula obtained was 10sm to A. Pintoi and 9sm + 1m to A. villosulicarpa. There was a predominance of pericentromeric C-band in all mitotic metaphasic chromosomes in both species. Besides C-band values, both species still did not differ in respect to chromosome absolute and relative lengths, centromeric index, symmetry index and total karyotype haploid length. C-band and morphometric data did not show strong or significant differences which could separate these two species of peanut which belong to evolutive different sections.

Giemsa staining and fluorescent chromosome banding in some Vitis L. species

Abstract Giemsa staining technique and fluorescent chromosome banding with CMA3 and DAPI were appliedto the mitotic chromosomes of Vitis champinii, V. cinerea, V. girdiana, V. labrusca, V. rotundifolia, V. rupestris and V. vinifera for the purpose of chromosome measurement and constitutive heterochromatin characterizationat the cytochemical level, respectively. Both fluorescent CMA and conventional Giemsa staining constituted a valuable tool for chromosome characterization. Karyomorphometric data obtained after Giemsa staining allowedfor an average ideogram and karyotype formulae based on chromosome length for the species. V. champinii and V. girdiana distinguished from the other five species by means of the total haploid chromosome length, by thelongest chromosome length and by the average chromosome length. The seven grape species have moderate chromosome asymmetry values and were classified on 2A Stebbins’ category. Positive CMA bands were seen in all species. V. girdiana distinguished from the other species solely by the presence of two CMA+ bands, while V. champinii, V. cinerea, V. labrusca, V. rotundifolia and V. rupestris had four bands. V. vinifera showed chromosome heteromorphism for CMA bands. No clearly visible DAPI+ band was seen in the species. According to the present observations, it seems that the evolutionary process of speciation involving North American and European Euvitis species studied, resulted in some discrete changes in chromosome measurements and also in heterochromatin basecomposition of at least one species. These data enlarge the chromosomal information of the genus Vitis and make possible further comparative studies into the Vitaceae family.

KARYOTYPE ANALYSIS IN GRAPEVINES

Seven species of Vitis L., V. champinii Planchon, V. cinerea (Engelm in Gray) Engelm, V. girdiana Munson, V. labrusca L., V. rotundifolia Michaux, V. rupestres Scheels and V. vinifera L. were studied with the purpose of complementing the karyomorphometric information for further comparative analyses. Based on ideograms and on chromosome measures obtained it was possible to see several differences among the species, which were enough to distinguish at least V. champinii and V. girdiana from the others as well as V. labrusca for the lowest measures and V. rotundifolia for the highest mean value of arm ratio. It seems that during the species diversification process the most crucial differences among them did not involve drastic changes in chromosome morphometry.

Cytological association between a knob on the short arm of chromosome 2 of maize and the latent-1 supergene

SUMMARYC-banding technique was applied in some maize materials with the purpose of verifing cytogenetical association between chromosome 2S knob and the presence and expression of latent-1 supergene and also mitotic chromosome characterization. Materials chosen were IP 48-5-3 Cateto Assis Brasil, its isoline IP 48-5-3-lte-1 carring latent-1 factor and Michoacan 21-1-104 latent-1 donnor. C-band number obtained was 3.26 ± 0.69 for IP 48-5-3 Assis Brasil, 7.86±1.57 for IP-48-5-3-lte-1 and 8.43 ±1.12 for Michoacan 21-1-104. The mean of total heterochromatin amount values obtained and expressed as percentage were 4.07±0.46; 9.68±1.59 and 13.99±2.05, respectively, C-band was used because of good correspondence between heterochromatic knobs and positive C-bands. IP 48-5-3 lte-1 isoline and Michoacan 21 showed positive C-band on short arm of chromosome 2 and IP 48-5-3 Assis Brasil did not show any band in the same chromosome.

Orcein, C- and NOR-banding on mitotic chromosomes of some wild diploid coffee species (Coffea L.)

The mitotic chromosomes of four diploid and auto-incompatible coffee species – Coffea congensis, C. eugenioides, C. liberica and C. stenophylla have been comparatively analyzed by acetic orcein, C-banding and nucleolar organizer region (NOR)-banding techniques in order to complete the chromosome characterization in the Coffea genus, by determining morphometric parameters and heterochromatin localization, and to establish karyotype traits, including the degree of symmetry/asymmetry of the karyotypes of the four studied species. The subject is of practical interest because botanical classification of coffee species is still controversial and the reported results can contribute to a better comprehension of interspecific relationships as well as of the evolutionary trends in Coffea. Some species differed from others based on some karyomorphometric parameters. The karyotype formula obtained was the same for all coffee species analyzed, 3m + 6sm + 2sms. All species displayed a moderate karyotype asymmetry and according to the Stebbins system, C. congensis and C. liberica were classified as 2A while C. eugenioides and C. stenophylla, classified as 2B, were more asymmetrical than the two former ones. Among the four indices used to assess karyotype asymmetry, Stebbins and Paszko AI indices were the best suited to individualize the species. C-bands occurred preferentially at pericentromeric/centromeric position. Two pairs of chromosomes with secondary constriction and satellite segments were observed in the species following acetic orcein staining. C. congensis, C. eugenioides and C. liberica displayed one pair of chromosomes with the NOR-band after silver staining procedure, while C. stenophylla showed two pairs. Data on morphometric chromosome and NOR-banding results were suitable for the characterization of the species.

Um caso de translocação em um híbrido entre Zea mays L. e Z. mexicana (Schrad.) Kuntze

Foi constatada, citologicamente, a presenca de uma translocacao heterozigota envolvendo dois cromossomos nao-homologos em um hibrido entre Zea mays L. e Z. mexicana (Schrad.) Kuntze. As analises citologicas foram feitas na microsporogenese das plantas hibridas, onde se observou a caracteristica configuracao em cruz que os cromossomos translocados assumem na fase de paquiteno, bem como as configuracoes em cadeia ou anel na diacinese e anel torcido na metafase I. A contagem dos graos de polen indicou 44,0% ± 1,2 de esterilidade, que foi atribuida diretamente a translocacao e nao a hibridacao. Devido ao mau espalhamento dos cromossomos na fase de paquiteno, nao se puderam identificar os cromossomos envolvidos na translocacao, estimando-se, porem, que estejam entre os tres cromossomos maiores do genoma (cromossomos 1, 2 e 3).