ABSTRACT South Brazilian grasslands are among the most species-rich grasslands worldwide yet they have been suffering ongoing degradation due to land-use. Little is known about the reproductive ecology of the native species of these grasslands. Thus, our goal was to characterize seed traits and germination requirements of three native species of the tribe Tigridieae (Iridaceae, Iridoideae) due to its richness in the Pampa biome and the contrasting morphology, cytogenetics, and geographic distributions of its representatives. We tested if closely related species possess similar seed traits and whether species with wider distributions have broader germination requirements. Seed production and mass were estimated, and morphological analyses, germination experiments and viability tests were performed. Principal component analysis (PCA) was used to describe correlations between seed traits and species’ distributions. Germination was assessed using time-to-event analysis and the Cox model. All seed traits differed among the analyzed species/cytotypes. Final germination percentage (FGP) averaged 39.1 % and with overall viability of 89.9 %. Germination tests showed that seeds benefit from negative photoblasty. Species/cytotypes with wider distributions and heavier and larger seeds generally had better germination performances than narrower distributed species/cytotypes with lighter and smaller seeds.

Abstract Sisyrinchium is the largest genus of Iridaceae in the Americas and has the greatest amount of cytological data available. This study aimed at investigating how genomes evolved in this genus. Chromosome number, genome size and altitude from species of sect. Viperella were analyzed in a phylogenetic context. Meiotic and pollen analyses were performed to assess reproductive success of natural populations, especially from those polyploid taxa. Character optimizations revealed that the common ancestor of sect. Viperella was probably diploid (2n = 2x =18) with two subsequent polyplodization events. Total DNA content (2C) varied considerably across the phylogeny with larger genomes detected mainly in polyploid species. Altitude also varied across the phylogeny, however no significant relationship was found between DNA content changes and altitude in our data set. All taxa presented regular meiosis and pollen viability (> 87%), except for S. sp. nov. aff. alatum (22.70%), suggesting a recent hybrid origin. Chromosome number is mostly constant within this section and polyploidy is the only source of modification. Although 2C varied considerably among the 20 taxa investigated, the diversity observed cannot be attributed only to polyploidy events because large variations of DNA content were also observed among diploids.

Abstract Evolutionary analyses have been widely used for evaluation of genetic diversity of natural populations and correlate these data to the fitness of the species, especially in the case of threatened species. Calydorea crocoides occurs in a restricted area at altitudes from 800 to 1500 m in southern Brazil and is considered endangered. A study assessing genetic diversity, cytogenetic features and ecological niche was performed aiming to characterize C. crocoides by multidisciplinary approaches. Molecular data highlighted that most of the total variation (76%; p < 0.001) was found within populations and the parameters of genetic diversity were high at the species level (PPB = 98.97%; I = 0.4319; h = 0.2821). Gene flow (Nm) was estimated in 0.97 individuals per generation. Cytogenetically, C. crocoides presents a bimodal karyotype and low asymmetry. DAPI banding pattern was uniform, but the CMA-signal evidenced a pericentric inversion in the population ESC688. The species presents high pollen viability and two different morphologies of pollen grains. Our data showed high levels of polymorphism maintained in this species that could ensure conservationist practices in which the main goal is to preserve the evolutionary potential of the species through the maintenance of genetic diversity.

Bromeliaceae is a morphologically distinctive and ecologically diverse family originating in the New World. Three centers of diversity, 58 genera, and about 3,140 bromeliad species are currently recognized. We compiled all of the studies related to the reproductive biology, genetic diversity, and population structure of the Bromeliaceae, and discuss the evolution and conservation of this family. Bromeliads are preferentially pollinated by vertebrates and show marked variation in breeding systems, from predominant inbreeding to predominant outcrossing, as well as constancy in chromosome number (2n = 2x = 50). Autogamous or mixed mating system bromeliads have a high inbreeding coefficient (F IS), while outcrossing species show low F IS. The degree of differentiation among populations (F ST) of species ranges from 0.043 to 0.961, which can be influenced by pollen and seed dispersal effects, clonal growth, gene flow rates, and connectivity among populations. The evolutionary history of the Bromeliaceae is poorly known, although some studies have indicated that the family arose in the Guayana Shield roughly 100 Mya. We believe that genetic, cytogenetic, and reproductive data will be essential for diagnosing species status and for assisting conservation programs.

Plants of the family Iridaceae are well represented in the grassland vegetation of southern Brazil, occurring in the Pampa and Atlantic Forest biomes. Nevertheless, little is known about the taxonomy and evolution of Iridaceae species in southern Brazil. The main goal of this review is to compile published information about South American Iridaceae, and to discuss the evolution and genetic diversity of the family presenting our own research data in the light of the published literature. The main focus is on the genera Calydorea, Cypella, Herbertia, and Sisyrinchium. Aspects of reproductive system and of pollinator attraction are also discussed.

Sisyrinchium micranthum Cav. is a member of the family Iridaceae, which is distributed over the American continent. In Brazil, this species is found, not only in disturbed areas and coastal regions, but is also very common in urban centers, such as public parks, during the spring. Chromosome counts for North American specimens are 2n = 32 and 2n = 48, whereas in southern Brazil, there is a polyploidy series with three chromosome numbers, 2n = 16, 2n = 32, and 2n = 48. Population analyses using DNA molecular markers are inexistent for this species, in spite of its wide distribution and morphological variation. To study the genetic population structure of S. micranthum, five natural populations were accessed in a conservation park within the Atlantic Rain Forest Biome in southern Brazil. Here, the chromosome numbers 2n = 16 and 2n = 48 had already been described. Molecular analysis showed that the populations are highly structured with low gene flow among them. The population with 2n = 48 was genetically less variable than and distinct from the other populations. Population genetics in relation to cytogenetic data provided new insights regarding the genetic diversification and mating system of S. micranthum.

A utilização do milho (Zea mays) na cultura de anteras é limitada devido ao baixo número de genótipos com alto potencial androgenético. A obtenção de micrósporos no estádio de desenvolvimento apropriado no início da cultura é um dos fatores cruciais para o sucesso do processo androgenético. Em genótipos brasileiros de milho não existem estudos relatando a correlação entre características citológicas e parâmetros morfológicos. Neste estudo, parâmetros morfológicos foram avaliados e associados com estádios específicos da microsporogênese em dois genótipos brasileiros de milho os quais foram semeados em diferentes locais (campo e câmara de crescimento). Para ambos os genótipos, as plantas crescidas na câmara de crescimento apresentaram atraso no desenvolvimento. O comprimento da espigueta e a razão comprimento da antera/comprimento da espigueta não são bons parâmetros uma vez que podem ser muito influenciados pelo ambiente. O comprimento da antera foi o melhor parâmetro para indicar o estádio de desenvolvimento do micrósporo. Todavia, variações entre genótipos e ambiente foram detectadas.

The use of maize in anther culture has been limited because only few genotypes presented a high androgenetic potential. Obtaining the proper stage of microspore development at culture initiation is one of the most crucial factors for success in the androgenesis. For Brazilian maize genotypes there are no studies reporting a correlation between cytological features and morphological parameters. In this study, morphological parameters were recorded and associated with cytological specific stages of the the microsporogenesis in two Brazilian maize genotypes that were sowed in different places (field and growing chamber). For both genotypes, the plants of the growing chamber presented a delay in development. Spikelets length and anther length/spikelet length ratio are not good parameters since they can be greatly influenced by the environment. The anther length was the more reliable parameter to correlate with a specific developmental stage. Nevertheless, variations between genotypes and environment were detected.

O objetivo deste trabalho foi analisar a performance agronômica e a estabilidade cromossômica de progênies transgênicas homozigotas de soja [Glycine max (L.) Merrill.], e confirmar a resistência dessas plantas a Anticarsia gemmatalis. Onze progênies com expressão dos genes cry1Ac, hpt e gusA foram avaliadas quanto às características agronômicas, em relação à cultivar parental IAS 5 não transformada. Análises citogenéticas foram realizadas em plantas transgênicas e não transgênicas. Duas das 11 progênies transgênicas também foram avaliadas quanto à resistência a A. gemmatalis, em bioensaios in vitro e in vivo. Dois controles negativos foram utilizados nos bioensaios: uma linha transgênica homozigota, com apenas o gene repórter gusA, e plantas de 'IAS 5' não transgênicas. A presença do transgene cry1Ac não afetou nem o desenvolvimento nem a produtividade das plantas. As plantas transgênicas apresentaram cariótipo normal. No bioensaio com folhas destacadas, as plantas cry1Ac exibiram completa eficácia contra A. gemmatalis, enquanto os controles negativos foram significativamente danificados. Ensaios com plantas inteiras confirmaram a elevada proteção do cry1Ac contra a lagarta-da-soja, enquanto as plantas 'IAS 5' não transgênicas e a linha homozigota gusA exibiram 56.5 e 71.5% de desfolhação, respectivamente. A presença do transgene cry1Ac não afeta a performance agronômica da soja (incluindo a produtividade) e confere elevada proteção a A. gemmatalis.

The objective of this work was to analyze the agronomic performance and chromosomal stability of transgenic homozygous progenies of soybean [Glycine max (L.) Merrill.], and to confirm the resistance of these plants against Anticarsia gemmatalis. Eleven progenies expressing cry1Ac, hpt and gusA genes were evaluated for agronomic characteristics in relation to the nontransformed parent IAS 5 cultivar. Cytogenetical analysis was carried out on transgenic and nontransgenic plants. Two out of the 11 transgenic progenies were also evaluated, in vitro and in vivo, for resistance to A. gemmatalis. Two negative controls were used in resistance bioassays: a transgenic homozygous line, containing only the gusA reporter gene, and nontransgenic 'IAS 5' plants. The presence of cry1Ac transgene affected neither the development nor the yield of plants. Cytogenetical analysis showed that transgenic plants presented normal karyotype. In detached-leaf bioassay, cry1Ac plants exhibited complete efficacy against A. gemmatalis, whereas negative controls were significantly damaged. Whole-plant feeding assay confirmed a very high protection of cry1Ac against velvetbean caterpillar, while nontransgenic 'IAS 5' plants and homozygous gusA line exhibited 56.5 and 71.5% defoliation, respectively. The presence of cry1Ac transgene doesn't affect the majority of agronomic traits (including yield) of soybean and grants high protection against A. gemmatalis.

Anteras de duas cultivares de soja foram cultivadas em meio de cultura basal B5 longo gelificado com agarose ou Phytagel®. Análises citológicas das anteras foram conduzidas durante os primeiros 45 dias de cultura para avaliar a viabilidade e o estágio de desenvolvimento dos micrósporos. A freqüência de formação de calos foi analisada após 45 dias do início da cultura. A análise da variância da viabilidade do micrósporo mostrou interações significativas de Cultivar X Agente Gelificante X Dias de Cultura. As freqüências de grãos de pólen viáveis diminuíram significativamente com o tempo de cultura, dentro de cada cultivar e agente gelificante testado. A interação Dia X Cultivar foi significante para as freqüências de grãos de pólen binucleados simétricos e estruturas multinucleados/multicelulares. O efeito do agente gelificante na freqüência de grãos de pólen binucleados simétricos e estruturas multinucleados/multicelulares não foi significante. Com relação às freqüências de calos e estruturas embriogênicas formadas, houve diferença significativa entre cultivares (IAS5= 14.8% e BRS 133=6.6%). O agente gelificante não mostrou efeito em tais freqüências.

Anthers of two soybean cultivars were cultured in B5 long basal culture media gelled with agarose or PhytagelTM. Cytological examinations of the anthers were carried out during the first 45 days of culture to assay the viability and developmental stage of microspores. Frequency of callus formation was recorded at 45 days of culture. The analysis of variance of the microspore viability assay showed significant Cultivar X Gelling Agent X Day of Culture interactions. The frequencies of viable microspores decreased significantly with time of culture, within each cultivar and gelling agent tested. The interaction Day X Cultivar was significant for the frequencies of binucleate symmetrical grains and multinucleate/multicellular structures. The effect of gelling agents on the frequency of binucleate symmetrical pollens grains and multinucleate/multicellular structures was not significant. About the frequencies of calli and embryogenic calli formed, a significant difference was detected between the cultivars (IAS5= 14.8% and BRS 133=6.6%). Gelling agents showed no effect over these frequencies.

Anteras obtidas de botões florais da cultivar IAS-5 de soja foram cultivadas em dois meios de cultura basais (B5 e B5 longo). Análises citológicas das anteras cultivadas in vitro foram realizadas durante os primeiros 20 dias de cultura, a fim de avaliar a viabilidade (por testes de carmim propiônico e FDA) e o estágio de desenvolvimento dos grãos de pólen. As freqüências de grãos de pólen viáveis variaram significativamente entre os tamanhos de botões florais na análise com carmim propiônico. O meio de cultura basal e o tamanho do botão floral não têm um claro efeito nas freqüências de pólens binucleados simétricos e multinucleados. Contagens cromossômicas de micrósporos metafásicos ao longo do período de cultura mostraram nível de ploidia superior ao normal (n=20).

Anthers obtained from flowers buds of soybean cultivar IAS-5 were cultured in two basal culture media (B5 and B5 long). Cytological examinations of the in vitro anthers were performed during the first 20 days of culture to assay the viability (by propionic-carmine and fluorescein diacetate tests) and the stage of development of pollen grains. The frequencies of viable pollen grains varied significantly between bud sizes on the propionic-carmine analysis. The basal culture media and bud size had no clear effect on the frequencies of binucleate symmetrical and multinucleate pollen grains. Chromosome counts of metaphasic microspores throughout the culture period showed microspores with higher ploidy level in addition to normal chromosome number (n=20).

Neste estudo foram testados os efeitos do choque térmico na indução androgenética em cultura de anteras de soja. Parte das anteras formam submetidas ao choque térmico de 4 ou 33ºC, enquanto as anteras controle formam mantidas a 25ºC. Análises citológicas formam realizadas ao longo dos 30 primeiros dias de cultura mostrando que a freqüência de grãos de pólen binucleados simétricos e multinucleados não difere entre os tratamentos e que os grãos de pólen multinucleados podem ser formados tanto a partir de uma mitose simétrica inicial como após uma mitose assimétrica. Em relação à indução embriogênica, os tratamentos também não diferem. Estes resultados sugerem que o tratamento de choque térmico não induz a rota esporofítica nos micrósporos de soja.

In this study the effect of cold and heat shock on androgenetic induction in soybean anther culture was tested. Anthers of soybean were subjected to 4 and 33ºC, while the anthers used for control were maintained at 25ºC. Cytological analysis done during the 30 days of culture showed that frequencies of symmetrical binucleated and multicellular pollen grain did not differ among temperature treatments. Multicellular pollen grain could be formed by symmetrical division, as well as by assymetrical division. In relation to the embryo induction, the results of the treatments did not differ too. These results suggested that these treatments did not induce a sporophytic pathway in soybean.

Este estudo visa estabelecer a associação entre o tamanho do botão floral e o estágio de desenvolvimento dos micrósporos em cultivares brasileiras de soja. A distribuição dos estágios de desenvolvimento dos micrósporos foi analisada, nos anos de 1995 e 1997, em botões florais jovens das cultivares Década, IAS5 e RS7. Os dados indicam que, para um dado intervalo de tamanho do botão floral, os micrósporos das diferentes cultivares estavam em distintos estágios de desenvolvimento, com as cultivares RS7 e Década exibindo estágios anteriores àqueles observados na cultivar IAS5. A distribuição dos estágios dos micrósporos entre as dez anteras de um mesmo botão floral foi também analisada nestas cultivares. As dez anteras de um mesmo botão estão claramente distribuídas em diferentes estágios de desenvolvimento. Cautela deve ser tomada ao adotar-se o procedimento padrão em cultura de anteras de utilizar o estágio de desenvolvimento dos micrósporos em uma única antera para representar a totalidade do botão floral.

This study was carried out to establish the association between floral bud size and the corresponding microspore developmental stages for Brazilian soybean cultivars. Microspore developmental stage distributions were examined in young buds from cv Década, IAS5 and RS7. The data indicated that for a given bud-size group, the microspores of different cultivars were at different developmental stages, with cv RS7 and Década distributed at the youngest and cv IAS5 at the most advanced stages. Microspore stages distribution were also compared among the ten anthers of the same bud of the above cultivars. The ten anthers from a given bud were clearly distributed at different developmental stages. Caution should be exercised when adopting the standard anther culture practice of using the microspore stage of one anther to represent the entire bud.

A androgênese é o fênomeno no qual um grão de pólen é capaz de alterar sua rota de desenvolvimento e originar um esporófito haplóide. Este processo ontogenético alternativo ainda é pouco conhecido, apesar de sua potencialidade tanto para estudos básicos como àqueles aplicados para melhoramento de plantas. O presente artigo tem como propósito revisar os fatores envolvidos no desvio da via gametofítica normal e os mecanismos fundamentais na indução da embriogênese do pólen.

Androgenesis is a phenomenon in which pollen grain changes its developmental pathway giving rise to haploid sporophyte. This alternative ontogenetic process is still not completely understood despite of its potencial to basic and applied studies, including crop improvement. The present article has the purpose of reviewing the factors related to the deviation of normal gametophytic route and the fundamental mechanisms of pollen embryogenesis induction.