ABSTRACT: The aim of this study was to investigate the effect of heat stress on 12 bean genotypes through the analysis of their reproductive biology in terms of flowering, pollen viability, meiotic behavior, and production. Plants were grown in a climate chamber at 25-20 °C (day and night) and at a high temperature treatment 37-26 °C (day and night) from the vegetative (V4) development stage to physiological maturity. The experimental design was 2 × 12 factorial arrangement with six replications and the factors consisted of heat treatments and genotypes. In three replications, the number of newly opened flowers was checked daily. At physiological maturity, the following traits were evaluated: percentage of pod set, number of pods, number of viable seeds, number of aborted seeds, 100 seed weight, and seed yield (g per plant). The other three replications were used to collect flowers to create slides to study viability of the pollen grain and analyze the meiotic behavior. The heat treatment factor significantly affected the following traits: total number of pollen grains, number of flowers, number of pods, pod set, number of viable seeds, 100 seed weight, and seed yield. The raised temperature reduced these variables, except for percentage of pod set, and increased meiotic irregularities. The mean values regarding seed yield were 16.39 g per plant for the control treatment and 7.46 g per plant under high temperature. IAC Imperador, FT Nobre, Pérola, BRS Estilo, and IAC Diplomata stood out for higher bean seed yield under increased temperature.

ABSTRACT: Presence of the ALMT1 (aluminum-activated malate transporter) gene confers resistance to aluminum toxicity in Triticum aestivum (common wheat). No resistant cultivars of Triticum turgidum ssp. Durum Desf. (durum wheat) have been registered in Brazil. The aim of this study was to map the ALMT1 through application of the FISH (fluorescence in situ hybridization) technique in five wheat genotypes, common and durum, from the Active Germplasm Bank (AGB) of the Instituto Agronômico (IAC): BH 1146, P19, P33, Anahuac, and IAC 1003. FISH-ALMT1 signals were registered in Anahuac (sensitive) chromosomes and in BH 1146, P19, and P33 (resistant) chromosomes. In the three resistant genotypes, a characteristic double FISH signal was found, located in different chromosomes of the complements: in BH 1146 in chromosome 5D, in P19 in 3B, and in P33 in 6B. This FISH - ALMT1 mapping allows for introgression of aluminum resistance in sensitive cultivars through breeding programs using introgression lines containing these carrier chromosomes.

ABSTRACT Parental plants, an F1 interspecific hybrid and the F2 generation from Arabusta coffee plants were investigated for meiotic behavior and viability of pollen to understand part of their reproductive biology that affects their possible use in coffee breeding programs. Both parental plants (C. canephora var. Robusta 4x and C. arabica var. dihaploid Bourbon Vermelho) showed a meiosis diploid-like behavior, despite presenting a small percentage of irregularities, just as occurred for the F1 Arabusta hybrid. On the other hand, all F2 plants showeda higher frequency of anomalies that compromised pollen viability. The highest meiotic indices were registered for three analyzed plants of the F2 generation, and the pollen viability tests revealed the highest values for staining (PVS) and germination in vitro tests (PVG) for three others different F2 plants. The meiotic analysis and pollen viability tests may facilitate the selection of the best genetic resources, reducing the time needed for producing new hybrid cultivars. F2 plants which have high meiotic indices and/or high pollen fertility could be used as pollen donors in crossbreeding programs when there is interest in their functional or morphological characteristics. In contrast, the F2 plants that showed low pollen viability could be exploited as sterile male plants or discarded from a breeding program.

ABSTRACT Karyotyping and chromosome complement knowledge are a prerequisite for cytogenetic mapping. The aim of this study was to characterize 1 common wheat cultivar (BH 1146) and 4 durum wheat genotypes (IAC 1003, Langdon, P19 and P33) from the breeding program of the Agronomic Institute of Campinas (IAC), using karyotype analysis together with Chromomycin A3/4’-6-Diamidino-2-phenylindole (CMA/DAPI) banding techniques for longitudinal characterization of chromosomes and fluorescence in situ hybridization (FISH) in the mapping of the 45S rDNA region. Durum wheat chromosome complement number was 2n = 4x = 28 with the following karyotype formula: 22m + 6sm. Common wheat chromosome complement number was 2n = 6x = 42 with the following karyotype formula: 34m + 8sm. Tetraploid and hexaploid genomes presented 2 pairs of chromosomes with secondary constriction and terminal satellites. All 5 wheat genotypes exhibited CMA and DAPI bands and signals in the 45S rDNA regions (FISH-probe pTa71) which varied in number and location on the chromosome complement. All lines showed greater amount of DAPI bands than CMA bands. The FISH-rDNA 45S in situ hybridization signals, related to the nucleolar organizing regions (NORs), were observed in common wheat, presenting signals for the 45S rDNA sequence in 3 pairs of chromosomes. Durum wheat presented signals in 2 pairs. The CMA bands coincided with the location of 45S rDNA region in the chromosomes of durum wheat. The techniques were efficient for chromosomal characterization of all 5 genotypes.

ABSTRACT The species Conyza bonariensis (L.) cause losses in agriculture due to their invasive capacity and resistance to herbicides like glyphosate. The species of this genus exhibit phenotypic plasticity, which complicates their identification and characterization. Thus, experiments were performed with 2 extreme C. bonariensis phenotypes (called broad leaf and narrow leaf) in greenhouse conditions and in the laboratory, in order to verify if the morphological differences among these phenotypes are a genetic character or result from environmental effects. In addition to the comparative morphological analysis, assessment of DNA methylation profile was performed to detect the occurrence, or not, of differences in the epigenetic level. The morphological characteristics evaluated were length, width, shape, margin and leaves indument; plant height and stem indument; the number of capitula, flowers and seeds. The Methylation Sensitive Amplified Polymorphism technique was used to investigate the methylation levels. The morphological differences of phenotypes supposed to be C. bonariensis are probably genetic in origin and not the result of environmental effects, since, after 6 crop cycles in a greenhouse under the same environmental conditions, these phenotypes remained with the same morphological characteristics and seed production in relation to the original phenotypes found in the collection site. The different phenotypes did not show differences corresponding to DNA methylation patterns that could indicate an epigenetic effect as the cause of the differences between the 2 phenotypes. The results of morphological analysis and methylation probably indicate that maybe they are individuals of populations from different taxa not registered yet in the literature.

Este é o primeiro estudo de biologia da reprodução e citologia realizado em Hypericum brasiliense, uma espécie com propriedades medicinais e de interesse agronômico. Três populações de H. brasiliense da região Sudeste do Brasil foram estudadas. Os resultados obtidos dos estudos indicam que H. brasiliense é uma espécie preferencialmente alógama, auto-compatível, apomítica facultativa e anemófila. Foi observada macho-esterilidade em 50% dos indivíduos estudados nas três populações. Estudos anatômicos evidenciaram anormalidades estruturais nas anteras de flores macho-estéreis, como células do tapete aumentadas, com grossas camadas de secreções depositadas em sua superfície que podem originar deficiências nutricionais para as células mães do pólen. Nos estudos citogenéticos diversos números haplóides foram observados, tais como n = 4, 8, 9, 11, 16 e 17, incluindo a presença de multivalentes e micronúcleos em tétrades, indicando a ocorrência de anormalidades no processo meiótico de H. brasiliense. Apesar das anormalidades meióticas a viabilidade polínica e o índice de germinação in vitro dos pólens observado para as flores férteis podem ser considerados altos. O número cromossômico diplóide registrado foi 2n = 16, com cromossomos metafásicos pequenos e similares entre si. Foram aplicadas técnicas de bandamento com fluorocromos DAPI e CMA3, sem que bandas positivas fossem observadas.

This is the first study of reproductive biology and cytology carried out with Hypericum brasiliense, a species with medicinal properties and potential agronomic interest. Three populations of H. brasiliense collected at Southeastern Brazil were studied. The results indicate that H. brasiliense is preferentially allogamous, self-compatible, facultative apomitic and anemophilous. Male sterility was observed in about 50% of individuals from the three populations. Anatomical studies evidenced structural abnormalities in anthers of male sterile flowers, showing enlarged tapetal cells and thick secretion deposits on the tapetal cell surfaces that may cause nutritional deficit for pollen mother cells. In cytogenetic studies several haploid chromosome numbers were observed like n = 4, 8, 9, 11, 16 and 17, including the presence of multivalents and micronuclei in tetrads, indicating the occurrence of abnormalities in the meiotic process of H. brasiliense. Despite these meiotic abnormalities the pollen viability and in vitro pollen germination rate observed in fertile flowers may be considered high. The diploid chromosome number 2n = 16 was observed, and the chromosomes in metaphase were small and similar. Fluorochrome staining techniques using DAPI and CMA3 were applied, with no positive bands observed.

O pólen das anonas comerciais, cherimóia (Annona cherimola Mill.), fruta-do-conde, pinha ou ata (Annona squamosa L.) e atemóia (Annona cherimola X Annona squamosa) têm período de viabilidade reduzido. Este fato, aliado à ocorrência de dicogamia protogínica nessas plantas, demanda metodologias de conservação que promovam maior longevidade ao pólen. Objetivou-se neste estudo a aplicação de técnicas de conservação do pólen dessas fruteiras. O pólen foi coletado de flores em estádio macho e conservado em nitrogênio líquido (-196 °C) e geladeira (4-5 °C). Utilizaram-se amostras de pólen dessecadas e não dessecadas, coletadas em período seco e úmido do ano. Pólen recém-coletado e não submetido à conservação, pólen fresco (PF), foi considerado padrão. O pólen amanhecido (PA) foi utilizado após 12 horas da coleta. A viabilidade polínica foi avaliada através de testes de coloração com o corante Alexander, germinação in vitro e polinização em campo. Para a germinação, utilizaram-se dois meios de cultura, o meio A e o BK e a viabilidade foi avaliada pela taxa de emissão de tubo polínico. O PF coletado em período úmido revelou maior viabilidade em relação ao do período seco. Nos testes de germinação in vitro ocorreu emissão de tubos polínicos para as amostras de PF e PA nas primeiras 12 horas. A emissão de tubos polínicos decaiu com o tempo de conservação. Nos testes de germinação in vitro e polinização em campo, o pólen das três fruteiras, conservado em geladeira, proporcionou maior viabilidade que o conservado em nitrogênio. Nas polinizações obtiveram-se frutificações com PF e PA coletados em período úmido e em período seco e ausência de frutificações nas polinizações com pólen conservado além de três dias, tanto em nitrogênio como na geladeira.

Pollen of commercial anonas, cherimoya (Annona cherimola Mill.), curstad apple (Annona squamosa L.) and atemoya (Annona cherimola X Annona squamosa) has a short viability time. This fact associated with the occurrence of protogynous dichogamy in these plants demands methodologies for pollen conservation that increases pollen longevity. The objective of this study was to apply pollen storage procedures to these fruit trees. The pollen was collected from flowers at male stage and conservation assays were performed in liquid nitrogen (_196°C) and refrigerator (4-5°C). Pollen samples were submitted to desiccation and some were not desiccated and were collected during dry and humid periods of the year. The freshly collected pollen without desiccation was denominated fresh pollen (PF) and was used as control. The freshly collected pollen that was used in the assays 12 hours after collection was denominated dawned pollen (PA). Pollen viability was evaluated by staining tests with Alexander stain, in vitro germination and hand pollination assays. In the in vitro germination assays culture mediums A and BK were used and the evaluation was based on pollen tube growth rate. The fresh pollen collected during humid period exhibited higher viability then the fresh pollen collected during dry period. In the in vitro germination tests the pollen tube growth was observed for samples of PF and PA in the first 12 hours. The rate of emitted tubes decreased as time of conservation raised. In the in vitro germination and pollinations tests the pollen samples conserved in the refrigerator exhibited higher viability than those on the nitrogen. The pollinations made with PF and PA pollen that were collected both in the humid and dry period resulted in fruit settings. There was no fruit set from pollinations made with any other pollen sample that was conserved either in nitrogen or refrigerator for more than three days.

Estudaram-se as causas biológicas do reduzido número de sementes da tangerina `Sunki' (Citrus sunki Hort. ex. Tan.), promissor porta-enxerto para a citricultura brasileira. As seguintes hipóteses foram investigadas: (1) existência de uma limitação na anatomia do fruto, decorrente do pequeno número de óvulos por ovário; (2) ocorrência de esterilidade gamética em função do desenvolvimento anormal do saco embrionário e/ou dos grãos de pólen; (3) presença de auto-incompatibilidade. Realizaram-se cortes histológicos de ovários e de sacos embrionários, observações detalhadas de frutos e suas sementes, bem como polinizações com outras espécies e cultivares. Concluiu-se que apesar de a tangerina `Sunki' produzir normalmente apenas duas a três sementes viáveis, possui potencial biológico para originar até dezessete sementes por fruto. A formação de gametas tanto masculinos como femininos é normal. Quanto ao reduzido número de sementes por fruto, pode-se explicá-lo em razão do acentuado grau de auto-incompatibilidade. Quando polinizada com espécies compatíveis, há um aumento significativo no número de sementes por fruto, cuja magnitude depende do polinizador específico utilizado. Em termos biológicos, é possível e praticamente exeqüível aumentar o número de sementes da tangerina `Sunki' por meio de polinizadores adequados, no entanto, esse aumento é acompanhado pelo maior número de plantas zigóticas e não de nucelares como seria de interesse comercial.

The biological causes for the reduced number of seeds per fruit in the `Sunki' mandarin (Citrus sunki Hort. ex Tan.), a promising citrus rootstock in Brazil, were studied. Three hypotheses were investigated: (1) existence of an anatomical limitation related to a reduced number of ovules in the ovary; (2) occurrence of sterility due to abnormal formation of the embryo sac and/or pollen grains; (3) self-incompatibility. Histological studies of the ovary, observations of fruits, seeds, and pollen grains as well as pollinations with other citrus species led to the conclusion that although `Sunki' fruits usually bear only two or three viable seeds, they have however, a biological potential to produce up to 17 seeds. The formation and viability of male and female gametes are normal. The main reason for the reduced number of seeds is the self-incompatibility of this clone. When pollinated with other species, there is a significant increase in the number of seeds/fruit of a magnitude dependent on the pollen source. Therefore, it is possible to increase the number of seeds/fruit with adequate pollinators although this will result in substantial increase only in the number of zygotic plants and not in the nucellar ones as would be commercially desirable.