Inheritance of aluminum tolerance in maize

The purpose of this study was to investigate aluminum tolerance in maize. For this purpose, a nutrient solutionwas used with the tolerant (L922) and sensitive (Ast214) homozygous parental lines, with the segregating generation F2 andwith the F2:3 lines derived thereof. Seeds were germinated on paper and seedlings transferred to a nutrient solution containing4.5 mg L-1 aluminum. In the experiments involving F2:3 derived lines groups of rows with F2:3 plants were intercropped withrows of eight seedlings of the parental lines in a completely randomized block design. Results of the F2 generation demonstrateda bimodal distribution of relative frequencies, with approximately three times more seedlings in the tolerant group. Thissuggests the participation of only one locus in tolerance inheritance. The narrow-sense heritability (F2, F2:3) of seminal rootlength of F2 plants and means of F2:3 lines was 0.49, which partially explained the bimodal frequency distribution of means ofF2:3 lines, but was not accurate enough to differentiate tolerant from sensitive groups

Molecular characterization of Cratylia argentea accessions and its phylogenetic relationship with other legumes

O objetivo deste trabalho foi realizar a caracterização molecular de 11 acessos de Cratylia argentea, com base no sequenciamento da região ITS (ITS1/5,8S/ITS2), bem como o estabelecimento de suas relações filogenéticas com outras leguminosas. As relações filogenéticas dessa espécie com outras 15 leguminosas foram estabelecidas com o uso de sequência do gene que codifica a subunidade 18S do rRNA (rDNA 18S). A amplificação do DNA da região ITS/5,8S dos 11 acessos revelou uma única banda de aproximadamente 650 pb. Sequências ITS/5,8S foram obtidas de todos os acessos analisados e depois alinhadas com a região ITS/5,8S da leguminosa Galactia striata. O tamanho das sequências ITS/5,8S dos acessos de C. argentea variou de 565 a 615 pb. Os conteúdos médios de G + C nas regiões ITS1 e ITS2 variaram entre 46 e 47%. O alinhamento múltiplo das seqüências ITS/5,8S dos acessos de C. argentea com Galactia striata revelou a presença de deleções e inserções. Os acessos de C. argentea constituíram um único clado politômico. A análise filogenética de C. argentea demonstrou que essa espécie está incluída no clado das Diocleinae verdadeiras e que os gêneros Calopogonium e Pachyrhizus estão fora desse clado.The objective of this work was to molecularly characterize 11 Cratylia argentea accessions, ITS (ITS1/5.8S/ITS2) region as well to establish its phylogenetic relationship using a gene sequence that codes the subunit 18S of the rRNA (rDNA 18S). DNA amplification of the ITS/5.8S region of these 11 accessions revealed an amplicon with around 650 bp. ITS/5.8S sequences were obtained from all accessions analysed, and then aligned with the region ITS/5.8S of Galactia striata legume. The size of ITS/5.8S region ranged from 565 to 615 bp. Average G + C contents in the ITS1 and ITS2 regions ranged between 46 and 47%. The multiple sequence alignment between the ITS sequences from C. argentea accessions and Galactia striata revealed the presence of deletions and insertions. C. argentea accessions formed a unique politomic clade. Cratylia argentea phylogenetic analysis demonstrated that this species is placed into the true Diocleinae Clade, and that Calopogonium and Pachyrhizus are not included in subtribe Diocleinae

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

Long-wavelength sensitive opsin (LWS) gene variability in Neotropical cichlids (Teleostei: Cichlidae)

ABSTRACT Cichlid fishes are an important group in evolutionary biology due to their fast speciation. This group depends widely of vision for feeding and reproduction. During the evolutionary process it plays a significant role in interspecific and intraspecific recognition and in its ecology. The molecular basis of vision is formed by the interaction of the protein opsin and retinal chromophore. Long-wavelength sensitive opsin (LWS) gene is the most variable among the opsin genes and it has an ecological significance. Current assay identifies interspecific variation of Neotropical cichlids that would modify the spectral properties of the LWS opsin protein and codons selected. Neotropical species present more variable sites for LWS gene than those of the African lakes species. The LWS opsin gene in Crenicichla britskii has a higher amino acid similarity when compared to that in the African species, but the variable regions do not overlap. Neotropical cichlids accumulate larger amounts of variable sites for LWS opsin gene, probably because they are spread over a wider area and submitted to a wider range of selective pressures by inhabiting mainly lotic environments. Furthermore, the codons under selection are different when compared to those of the African cichlids

Heteroplasmia para o gene mitocondrial T-urf13 do citoplasma texas de milho

In maize (Zea mays L.), the Texas (T) cytoplasm carries male sterility (cms-T) and susceptibility to host-specific fungal toxins and to the insecticide methomyl, traits of great interest both for basic research and plant breeding. These traits are apparently inseparable, and they are directly associated with the T-urf13 mitochondrial gene, which encodes a 13-kilodalton protein (URF13). Reversion to male fertility, associated with toxin/methomyl resistance, has been observed in progenies of cms-T somaclones regenerated from methomyl resistant calli. Diversity for PCR amplification of T-urf13 sequence and URF13 expression was observed within revertant progenies. Apparently, this diversity occurred among tissues within ear and tassel, and between ears and tassels of individual plants. The results demonstrate heteroplasmy in T-urf13 sequence persisting through several generations of T-cytoplasm mutants, that apparently consisted of deletions and sequence alterations. Furthermore, URF13 deficiency suggested that total or partial cytoplasmic reversions to male fertility in cms-T somaclones are caused by T-urf13 heteroplasmyEm milho (Zea mays L.), o citoplasma texas (T) condiciona macho-esterilidade (cms-T) e susceptibilidade à toxina de fungos e ao inseticida metomil, características de grande interesse para estudos básicos e melhoramento de plantas. Essas características são aparentemente inseparáveis e estão diretamente associadas ao gene mitocondrial T-urf13, que codifica uma proteína de 13 kilodaltons (URF13). Reversão para fertilidade masculina, associada à resistência à toxina/metomil, tem sido observada em progênies de somaclones cms-T, derivados de calos resistentes ao metomil. Foi encontrada diversidade para amplificação via PCR do gene T-urf13 e para expressão da proteína URF13 nesses somaclones revertentes. Aparentemente, esta diversidade ocorre dentro de tecidos de espiga e panícula e entre espiga e panícula de uma mesma planta. Os resultados demonstram heteroplasmia na seqüência T-urf13, que persistiu em várias gerações desses mutantes, consistindo aparentemente de deleções e alterações na seqüência de DNA. Além disso, deficiência da proteína URF13 em somaclones férteis sugeriu que a reversão total ou parcial da macho-fertilidade é causada pela heteroplasmia no gene T-urf1

<b>Molecular variants in populations of <i>Bryconamericus</i> aff. <i>iheringii</i> (Characiformes, Characidae) in the upper Paraná river basin</b> - doi: 10.4025/actascibiolsci.v35i2.11451

There are evidences that Bryconamericus aff. iheringii represents a species complex. DNA molecular markers have been effective in studies on phylogeny, taxonomy, and identification of cryptic species. In this study, partial sequences of genes of ATPase 6 and 8 were used to assess genetic diversity within and among populations of B. aff. iheringii of sub-basins of Tibagi, Pirapó and Ivaí rivers, belonging to the Upper Paraná river basin. The analysis of the sequences of genes pointed out high genetic diversity in B. aff. iheringii from the sub-basins studied with genetic distance values comparable to those found among different species. There was a division of the individuals into five groups. The comparison with other species of Bryconamericus that have sequences available in GenBank confirmed that the individuals studied have relevant values of genetic distance, found among different species. Nevertheless, with the available data it is not possible to refute the hypothesis that the populations correspond to a group resulting from hybridization or that there might have been introgression of mitochondrial DNA among different species

Opsin genes: research perspectives with Neotropical cichlids (Perciformes: Cichlidae) and their relevance in floodplain studies

Vision not only plays an important role in the behavior and exploration capacity of new ecology niches but also influences the evolution of species exposed to the heterogeneity of light. Floodplain environments have high habitat heterogeneity and, thus, different light gradients. Cichlids are a group of vertebrates that has stirred interest in evolutionary studies due to their morphological and behavioral diversity and their widely used vision. The molecular basis of vertebrates’ vision occurs through the interaction of opsin proteins and retinal chromophores. Proteins are expressed by opsin genes where each is responsible for absorbing certain light wavelengths.  Current review analyzes the main characteristics of opsin genes family and the possibility of using them in floodplain and Neotropical cichlids studies. Opsins may have different levels of expression and molecular polymorphisms according to the dispersion of the species. They are also related to such behavior as sexual selection, nourishment and exploration of new habitats. Floodplains are natural experiments and dynamic environments that provide a wide range of habitats. In fact, the integration of studies in floodplains and the opsin genes in Neotropical cichlids seems to be a promising and still unexplored area in Neotropical regions.

Obtaining 5S rDNA molecular markers for native and invasive Cichla populations (Perciformes – Cichlidae), in Brazil - DOI: 10.4025/actascibiolsci.v30i1.1467

The 5S rDNA gene is informative and has high conservation rates along the eukaryotic genome, having unique hereditary characteristics. Molecular studies with the 5S rDNA gene have been carried out with several groups, including some species of fish, aiming at solving phylogenetic relationship problems, ancestral patterns and genetic diversity among groups in natural populations. Species of the Cichla genus, introduced in the Upper Paraná River basin, present some genetic polymorphisms detected by RAPD and SPAR analyses. These species have been intercrossing and forming viable hybrids, with greater genetic variability. The objective of this work was to standardize the amplification methodology for the non-transcribed regions of 5S rDNA multigenic family of Cichla, and to obtain specific markers for parent species that could also be identified in the hybrids. Sixty-five specimens of Cichla collected from the Upper Paraná River and Amazon basins were analyzed. Although molecular markers that could be useful in the identification of hybrids were not obtained, genetic molecular 5S rDNA species-specific markers for Cichla temensis that can be employed to identify of this species, as well population markers that can be useful in population genetic variability studies, were obtainedO gene DNAr 5S é informativo e possui altas taxas de conservação ao longo do genoma dos eucariotos, possuindo características únicas que são hereditárias. Estudos moleculares do gene DNAr 5S vem sendo realizados com diversos grupos, inclusive em algumas espécies de peixes, com o intuito de solucionar problemas de relações filogenéticas, padrão de ancestralidade e diversidade genética, entre grupos de populações naturais. Espécies do gênero Cichla, introduzidas na bacia do alto rio Paraná, apresentam polimorfismos genéticos, detectados por análise de RAPD e SPAR. Essas espécies estão intercruzando-se e formando híbridos viáveis, com maior variabilidade genética. O objetivo desse trabalho foi padronizar a metodologia de amplificação de regiões não-transcritas da família multigênica rDNA 5S de Cichla e obter marcadores específicos para as espécies parentais que pudessem, também, ser identificados nos híbridos. Foram analisados 65 espécimes de Cichla, das bacias do alto rio Paraná e Amazônica. Apesar de não se obter marcadores moleculares que pudessem ser úteis à identificação de híbridos, foram obtidos marcadores moleculares genéticos DNAr 5S espécie-específicos para Cichla temensis, que podem ser utilizados para identificação de exemplares dessa espécie e, também, marcadores populacionais, que podem ser úteis para estudos de variabilidade genética populaciona

Obtaining 5S rDNA molecular markers for native and invasive Cichla populations (Perciformes – Cichlidae), in Brazil = Obtenção de marcadores moleculares 5S rDNA para populações nativas e introduzidas de Cichla (Perciformes – Cichlidae), do Brasil

The 5S rDNA gene is informative and has high conservation rates along the eukaryotic genome, having unique hereditary characteristics. Molecular studies with the 5S rDNA gene have been carried out with several groups, including some species of fish, aiming at solving phylogenetic relationship problems, ancestral patterns and geneticdiversity among groups in natural populations. Species of the Cichla genus, introduced in the upper Paraná river basin, present some genetic polymorphisms detected by RAPD and SPAR analyses. These species have been intercrossing and forming viable hybrids, withgreater genetic variability. The objective of this work was to standardize the amplification methodology for the non-transcribed regions of 5S rDNA multigenic family of Cichla, and to obtain specific markers for parent species that could also be identified in the hybrids. Sixty-five specimens of Cichla collected from the upper Paraná river and Amazon basins were analyzed. Although molecular markers that could be useful in the identification of hybrids were not obtained, genetic molecular 5S rDNA species-specific markers for Cichla temensis that can be employed to identify of this species, as well population markers that can be useful in population genetic variability studies, were obtained.O gene DNAr 5S é informativo e possui altas taxas de conservação ao longo do genoma dos eucariotos, possuindo características únicas que são hereditárias. Estudos moleculares do gene DNAr 5S vem sendo realizados com diversos grupos, inclusive em algumas espécies de peixes, com o intuito de solucionar problemas de relações filogenéticas, padrão de ancestralidade e diversidade genética, entre grupos de populações naturais. Espécies do gênero Cichla, introduzidas na bacia do alto rio Paraná, apresentam polimorfismos genéticos, detectados por análise de RAPD e SPAR. Essas espécies estão intercruzando-se e formando híbridos viáveis, com maior variabilidade genética. O objetivo desse trabalho foi padronizar ametodologia de amplificação de regiões não-transcritas da família multigênica rDNA 5S de Cichla e obter marcadores específicos para as espécies parentais que pudessem, também, ser identificados nos híbridos. Foram analisados 65 espécimes de Cichla, das bacias do alto rio Paraná e Amazônica. Apesar de não se obter marcadores moleculares que pudessem ser úteis à identificação de híbridos, foram obtidos marcadores moleculares genéticos DNAr 5S espécie-específicos para Cichla temensis, que podem ser utilizados para identificação deexemplares dessa espécie e, também, marcadores populacionais, que podem ser úteis para estudos de variabilidade genética populacional