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In Rio Grande do Sul, the main rice producer State in Brazil, low temperatures can occur during germination and seedling establishment, and in some cases, during the reproductive stage. When low temperatures occur in the early developmental stages cause delay in germination, resulting in a non-homogeneous growing. In reproductive stage, low temperatures cause spikelet sterility, directly interfering with plant yield. Researchers have shown that some phenolic compounds such as proanthocyanidins and anthocyanin are associated with low temperature tolerance in plants due to their antioxidant capacity. The red and black color in the seeds of some rice genotypes is conferred by the phenolic compounds proanthocyanidins and anthocyanin, respectively. Therefore, tis study aimed to verify whether rice genotypes with red or black seeds are more tolerant to low temperatures during germination. In this study, five rice genotypes were tested, two present seeds without pigmentation and with contrasting response to low temperature tolerance (BRS Bojuru - tolerant and BRS Pampeira - sensitive), two genotypes with red seeds (BRS 902, SCS 119 Rubi) and one black seed genotype (SCS 120 Ônix). As expected, the genotypes with pigmented seeds had a greater total phenolic compounds content. However, under low temperature conditions, the genotypes with pigmented seed showed a similar response to the sensitive genotype. Therefore, the presence of proanthocyanidins and anthocyanin in the seed of the studied genotypes does not provide tolerance to low temperatures during germination.

Rice production (Oryza sativa L.) is among the most economically important activities in the world. However, soil and salinity coming from irrigation water reduce rice yield. Therefore, the identification and/or development of salt-tolerant rice genotypes is a strategy to minimize this problem. The development of new genotypes depends on the presence of genetic diversity, and understanding the heritability of a desired trait can help in the selection process. Thus, this study aimed to identify superior genotypes, analyze the genetic diversity and estimate the heritability for salinity tolerance at the seedling stage in rice genotypes used in Brazil. For this, seedlings of 69 genotypes were kept in hydroponic solution with 40 mM NaCl (4 dSm-1) for seven days. Shoot length, root length, shoot dry weight, and root dry weight) were evaluated and the results were converted into relative performance. Tolerant and moderately salt-tolerant genotypes were identified at the seedling stage, which can be used in breeding programs and can be cultivated in high salinity areas. Principal component analysis showed the presence of genetic diversity for salinity response. Finally, it was shown that most of the observed variation is of genetic origin, which can make the breeding process less difficult.

The genus Vitis belongs to the Vitaceae family and is divided into two subgenera: Muscadinia and Vitis, the main difference between these subgenera being the number of chromosomes. There are many hypotheses about the origin of the genus, which have been formed with archaeological studies and lately with molecular analyses. Even though there is no consensus on the place of origin, these studies have shown that grapes have been used by man since ancient times, starting later on its domestication. Most studies point to the Near East and Greece as the beginning of domestication, current research suggests it took place in parallel in different sites, but in all cases Vitis vinifera (L.) subsp. sylvestris [Vitis vinifera (L.) subsp. sylvestris (Gmelin) Hagi] seems to be the species chosen by our ancestors to give rise to the now known Vitis vinifera (L.) subsp. vinifera [=sativa (Hegi)= caucasica (Vavilov)]. Its evolution and expansion into other territories followed the formation of new empires and their expansion, and this is where the historical importance of this crop lies. In this process, plants with hermaphrodite flowers were preferentially selected, with firmer, sweeter, larger fruits of different colors, thus favoring the selection of genes associated with these traits, also resulting in a change in seed morphology. Currently, genetic improvement programs have made use of wild species for the introgression of disease resistance genes and tolerance to diverse soil and climate environments. In addition, the mapping of genes of interest, both linked to agronomic and fruit quality traits, has allowed the use of molecular markers for assisted selection. Information on the domestication process and genetic resources help to understand the gene pool available for the development of cultivars that respond to producer and consumer requirements.

Wheat is a staple food for a large part of the world's population and faces a continuous demand for increased productivity. The presence of genetic variability allows the success in developing cultivars with higher yield. The understanding of the genetic variability available is crucial for their effective use in breeding programs. Inheritance of wheat yield components is complex, due to polygenic control and the strong influence of the environment. Therefore, an accurate heritability estimation can accelerate the selection gains towards increasing wheat yield. Thus, this study aimed to characterize agronomic traits related to yield in a collection of 99 wheat accessions used in Brazil. In addition, the heritability of these traits was estimated. The studied accessions showed variability for yield, which can be explained by the presence of variability in most yield components. Cluster analysis showed that there is variability in wheat genotypes, however, the introduction of new sources of variability in crossing blocks or the induction of mutations is suggested. The broad-sense heritability for grain yield was considered high, as well as for most of the studied agronomic traits, suggesting that it is possible to obtain genetic gain with selection in this environment. However, for greater accuracy, genetic gain values should be estimated and considered when designing selection strategies. Hectoliter weight showed low heritability, demonstrating the complexity of selection for this trait. In summary, this study demonstrates the presence of genetic variability and high heritability for agronomic traits, enabling genetic gain in breeding programs using these wheat accessions.

Maize (Zea mays L.) is the cereal most produced in the world, due to its wide scope and utilization in human and animal diet. This study aims to evaluate the agronomic performance of intervarietal maize hybrids, as well as the linear associations, interrelations of cause and effect, and the genotypes dispersion through canonical variates. The experiment was conducted in the agricultural year of 2014/2015. The crosses that originated the hybrids were carried out on the growing season of 2013/2014 and hybrids evaluated on 2014/2015. The hybrids were arranged in randomized blocks, being 13 treatments with five repetitions. The measured characters were: plant height, spike insertion height, stem diameter, spike diameter, spike length, spike mass, number of rows of grains per spike, number of grains per row, cob diameter, cob mass, spike grains mass, mass of a thousand grains, grain length and grain yield. The data were submitted to analysis of variance and mean values compared by the Tukey test at 5% of probability. The Pearson’s linear correlation analysis and path analysis were performed using grain yield as a dependent character. Furthermore, the analysis of canonical variables was carried out. The hybrid H5: G3 X G4 revealed higher grain yield, spike grains mass, number of grains per row and spike diameter. Grain yield of intervarietal hybrids presented positive correlations with the traits such as stem diameter, spike diameter, spike length, number of grains per row, mass of a thousand grains, grain length and spike grains mass. Spike diameter and spike length presented higher direct effects on grain yield of intervarietal hybrids. The canonical variates revealed the formation of five phenotypically distinct groups of intervarietal hybrids.

The morphological characterization allows one to estimate and evaluate the genetic distance among different varieties, identifying heterotrophic groups by means of clustering methods. The objectives of the study were to characterize improved open-pollinated varieties (VPAs) and maize landraces based on the main quantitative agronomic traits and to estimate the variability and similarity between them. Sixteen maize varieties from the southern region of the State of Rio Grande do Sul, Brazil were evaluated. Data were subjected to analysis of variance. For the characterization, the Tukey averages comparison test was performed. The similarity among the varieties was tested using the Tocher optimization method. The differences detected indicate the presence of genetic variability among the studied varieties. According to the Tocher grouping, it was found that some populations have the potential to be selected as parents in breeding programs, maximizing the variability obtained from their crosses. For certain traits, maize landraces do not differ from improved varieties and show high similarity.

In the present work, we study the genetic control of reproductive traits under different heat stress conditions in two populations of inbred lines derived from crosses between two S. pimpinellifolium accessions and two tomato cultivars (E9×L5 and E6203×LA1589). The temperature increase affected the reproductive traits, especially at extremely high temperatures, where only a few lines were able to set fruits. Even though a relative modest number of QTLs was identified, two clusters of QTLs involved in the responses of reproductive traits to heat stress were detected in both populations on chromosomes 1 and 2. Interestingly, several epistatic interactions were detected in the E9×L5 population, which were classified into three classes based on the allelic interaction: dominant (one locus suppressed the allelic effects of a second locus), co-adaptive (the double-homozygous alleles from the same parent alleles showed a higher phenotypic value than the combination of homozygous alleles from alternative parents) and transgressive (the combination of double-homozygous alleles from different parents showed better performance than double-homozygous alleles from the same parents). These results reinforce the important role of non-additive genetic variance in the response to heat stress and the potential of the new allelic combinations that arise after wide crosses., This research was funded by the European Commission H2020 Research and Innovation Program through the TomGEM project, grant agreement no. 679796; HARNESSTOM, grant agreement no. 101000716; G2P-SOL, grant agreement no. 677379. L.C.d.M. was supported by the Visiting Professor scholarship 88881.173041/2018-01 from the Coordination for the Improvement of Higher Education Personnel (CAPES), Ministry of Education of Brazil.

Italian ryegrass (Lolium multiflorum, LOLMU) is one of the most troublesome weeds in temperate regions in the world. This weed species interfere with wheat, corn, rye, and oat, causing significant crop yield losses. This species has evolved glyphosate resistance, making it difficult to control. The mechanisms of glyphosate resistance are still unknown, and an understanding thereof will favor the development of new strategies of management. The present study is the first transcriptome study in LOLMU using glyphosate-resistant and -sensitive biotypes, aiming to identify and to provide a list of the candidate target genes related to glyphosate resistance mechanism. The transcriptome was assembled de novo, producing 87,433 contigs with an N50 of 740 bp and an average length of 575 bp. There were 92 and 54 up- and down-regulated genes, respectively, in the resistant biotype, while a total of 1683 were differentially expressed in the sensitive biotype in response to glyphosate treatment. We selected 14 highly induced genes and seven with repressed expression in the resistant biotype in response to glyphosate. Of these genes, a significant proportion were related to the plasma membrane, indicating that there is a barrier making it difficult for glyphosate to enter the cell.

Rice WRKYs comprise a large family of transcription factors and present remarkable structure features and a unique DNA binding site. Their importance in plants goes beyond the response to stressful stimuli, since they participate in hormonal pathways and developmental processes. Indeed, the majority of WRKYs present an independent activation since they are able to perform self-transcriptional regulation. However, some WRKY activation depends on epigenetic and transcript regulation by micro RNAs. Their protein function depends, almost always, on the posttranslational changes. Taking to account its properties of auto-activation, all these regulators process are extremely important for complete WRKY regulation. In this sense, here we provide an overview of transcriptional activation and posttranscriptional and posttranslational regulation of rice WRKY genes under stresses.

The main aim of this study was to investigate the phenotypic correlation of yield component traits using several environmental stratifications methods. We also aimed to propose cause and effect of relationships for grain yield components in soybean genotypes under several environmental conditions. The tests were conducted in the agricultural year of 2013/2014 in four growing sites in Rio Grande do Sul, Brazil. The experimental arrangement was randomized blocks in factorial scheme (11 x 4), consisting eleven soybean genotypes in four environments with four repetitions each. All the growing environments Tapera-RS, Derrubadas-RS and Frederico Westphalen-RS were classified as favorable for soybean cultivation. The traits such as total number of pods per plant, number of branches and number of pods with 2-3 grains showed significant linear correlations with grain yield in both methods of analysis. The path analysis was applied under favorable and unfavorable environments to accurately estimate the direct and indirect effect of traits on soybean grain yield. The mass of a thousand grains and plant height were highly associated with grain yield but mostly influenced by environmental effects. The total number of pods should be prioritized for selecting superior soybean genotypes due to its direct and indirect effects on grain yield. It has shown constant in all environmental conditions. The direct effects of number of branches and number of pods (with one grain) presented distinct effects on yield in favorable and unfavorable environments.

The objective of this study was to relate the activation of enzymatic antioxidant system to the production of reactive oxygen species induced by salt stress. Rice (Oryza sativa L.) genotypes BRS Bojuru and BRS Pampa, tolerant and sensitive to salinity, respectively, were subjected to 150 mM NaCl for 0, 6, 24, 48, and 72 h. A significant increase of superoxide anion and H2O2 and a decrease in malondialdehyde (MDA) content were observed in the tolerant genotype, whereas in the sensitive genotype, there was no change in superoxide anion content, reduced H2O2 content, and increased MDA content. The superoxide dismutase (SOD) activity increased significantly in both genotypes, and increases in amounts of transcript were observed for OsSOD3Cu/Zn and OsSODA1-Mn in the tolerant genotype and for OsSOD4-Cu/Zn, OsSOD3-Cu/Zn, OsSODCc1-Cu/Zn, OsSOD-Fe, and OsSODA1-Mn in the sensitive genotype. The activities of catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were not significantly and consistently changed, but OsCATA, OsAPX2 and OsGR1 were induced in both genotypes. OsCATB transcription was increased in the tolerant genotype and OsCATC and OsAPX3 in the sensitive genotype under salinity. It is concluded that OsAPX3, OsGR2, OsGR3, and OsSOD3-Cu/Zn genes are the most suitable to distinguish tolerant from sensitive genotypes under salt stress.

Background: Fusarium Head Blight (FHB) is a worldwide devastating disease of bread wheat (Triticum aestivum L.). Genetic resistance is the most effective way to control FHB and many QTL related to this trait have been mapped on the wheat genetic map. This information, however, must be refined to be more efficiently used in breeding programs and for the advance of the basic research. The objective of the present study was to in-depth analyze the QTLome of FHB resistance in bread wheat, further integrating genetic, genomic, and transcriptomic data, aiming to find candidate genes. Methods: An exhaustive bibliographic review on 76 scientific papers was carried out collecting information about QTL related to FHB resistance mapped on bread wheat. A dense genetic consensus map with 572,862 loci was generated for QTL projection. Meta-analysis could be performed on 323 QTL. Candidate gene mining was carried out within the most refined loci, containing genes that were cross-validated with publicly available transcriptional expression data of wheat under Fusarium infection. Most highlighted genes were investigated for protein evidence. Results: A total of 556 QTL were found in the literature, distributed on all sub-genomes and chromosomes of wheat. Meta-analysis generated 65 meta-QTL, and this refinement allows one to find markers more tightly linked to these regions. Candidate gene mining within the most refined meta-QTL, meta-QTL 1/chr. 3B, harvested 324 genes and transcriptional data cross-validated 10 of these genes, as responsive to FHB. One is of these genes encodes a Glycosiltransferase and the other encodes for a Cytochrome P450, and these such proteins have already been verified as being responsible for FHB resistance, but the remaining eight genes still have to be further studied, as promising loci for breeding. Conclusions: The QTLome of FHB resistance in wheat was successfully assembled and a refinement in terms of number and length of loci was obtained. The integration of the QTLome with genomic and transcriptomic data has allowed for the discovery of promising candidate genes for use in breeding programs.

To obtain superior genotypes, the use of natural genetic variability is essential, aiming to select parents that will make future crossings blocks. Therefore, the aim of this study was to determine the genetic variability and dissimilarity using multivariate analyzes in common black bean accessions native to southern Brazil. The experiment was conducted in the 2014/2015 in Frederico Westphalen – RS. The experimental design was augmented blocks (RCBD) with four repetitions (totally 149 treatments), in which 147 black common bean accessions were evaluated. Two commercial cultivars were used as witnesses: BRS Esplendor and BRS Supremo. The phenotypic traits such as days to flowering, plant height at flowering, days to maturity, plant height at maturity, insertion of the first pod, number of pods per plant, number of seeds per pod, mass of seeds per pod, number of branches, mass of seeds per plant, seed length, seed width, seed flattening, seed brightness, presence of halo, color of the halo were measured. The distributions of phenotypic frequencies indicate genetic variability among the 149 genotypes of common black bean. The Tocher optimization method presents the formation of eight groups of genotypes. The dendrogram formed by the standardized Euclidean distance was efficient in the stratification of the accessions for their genetic distance. The relative contribution evaluated by Singh method shows that the characters days to flowering and seed brightness are those that best discriminate the genotypes. The multivariate techniques of Tocher optimization and the standardized Euclidean distance show similar responses, proving to be viable tools for the choice of parents in a breeding program.

The aim of this study was to determine the phenotypic adaptability and stability of the soybeans grown in different environments of Rio Grande do Sul through bissegmented regression analysis, factor analysis and AMMI. The experiment was held in 2013/2014 season in a randomized block design factorial (six environments cultivation × 20 genotypes of soybean), arranged in three replications. The results showed that methods of adaptability and stability have similar responses to the rank of environments. The Tenente Portela - RS, Arroio Grande - RS lowland and coxilha were favorable environments, while Santa Rosa - RS and Campos Borges -RS have been recognized unfavorable for soybean genotypes. Differential responses were obtained for the Sarandi - RS environment, where the factor analysis and regression bissegmented revealed that this is a favorable environment, while the method AMMI indicated negative scores and unfavorable. Genotypes TMG 7161 RR and NA5909 RR were indicated as high productivity and recommended for favorable environments for both methods. To reconcile bissegmented regression, factor analysis and AMMI accurately predicted the best genotypes and environments for soybean.

The chemical analysis of market-available white oat cultivars allows for their optimized use for processing, consumption, and in blocks of crosses. The purpose of this study was to evaluate the per...

The growing demand for fossil-based energy sources has increased oil pollution worldwide. Oil pollution is harmful because 75% of its components are polycyclic aromatic hydrocarbons, which are molecules known to present carcinogenic, mutagenic and teratogenic effects. Mangrove areas are commonly affected by petroleum accidents, making these ecosystems particularly sensitive to oil pollution. In order to elucidate the molecular response of a petroleum mixture on plants, the global gene expression analysis of 10-day-old Arabidopsis thaliana exposed to the water soluble fraction of the marine fuel MF380 (WSF-MF380) was evaluated by a 24 h time-course microarray. The microarray results revealed that 340 genes were modulated by WSF-MF380 stress; these genes were distributed in 12 clusters according to their expression profile. Different classes of biological processes were overrepresented, such as the response to heat, hypoxia, oxidative and osmotic stresses. The expression pattern of five transcription factors and 16 possible targets with enriched cis-regulatory elements was further investigated by qPCR at three selected time-points, revealing that the expression of selected target genes are in accordance with the expression profile of their possible regulator. We further demonstrate that WSF-MF380 stress gives rise to a high induction of genes at the initial time-point t2 h, indicating a rapid molecular response in plants. At t2 h, many HSP genes were induced, showing a similar expression profile in WSF-MF380 and heat stresses. In contrast to the initial induction, many iron deficiency genes, such as bHLH38, bHLH39, bHLH100 and bHLH101, were down regulated from t3 h to t24 h, with no GUS activity observed in the roots of pbHLH38:GUS transgenic A. thaliana after 16 h of exposure. Taken together, these analyses demonstrate that WSF-MF380 exposure seems to encompass a general response to abiotic stresses in plants, which could be an evidence of the complex chemical composition of the oil.

Background SUMOylation is an essential eukaryotic post-translation modification that, in plants, regulates numerous cellular processes, ranging from seed development to stress response. Using rice as a model crop plant, we searched for potential regulatory points that may influence the activity of the rice SUMOylation machinery genes. Results We analyzed the presence of putative cis-acting regulatory elements (CREs) within the promoter regions of the rice SUMOylation machinery genes and found CREs related to different cellular processes, including hormone signaling. We confirmed that the transcript levels of genes involved in target-SUMOylation, containing ABA- and GA-related CREs, are responsive to treatments with these hormones. Transcriptional analysis in Nipponbare (spp. japonica) and LC-93-4 (spp. indica), showed that the transcript levels of all studied genes are maintained in the two subspecies, under normal growth. OsSUMO3 is an exceptional case since it is expressed at low levels or is not detectable at all in LC-93-4 roots and shoots, respectively. We revealed post-transcriptional regulation by alternative splicing (AS) for all genes studied, except for SUMO coding genes, OsSIZ2, OsOTS3, and OsELS2. Some AS forms have the potential to alter protein domains and catalytic centers. We also performed the molecular and phenotypic characterization of T-DNA insertion lines of some of the genes under study. Knockouts of OsFUG1 and OsELS1 showed increased SUMOylation levels and non-overlapping phenotypes. The fug1 line showed a dwarf phenotype, and significant defects in fertility, seed weight, and panicle architecture, while the els1 line showed early flowering and decreased plant height. We suggest that OsELS1 is an ortholog of AtEsd4, which was also supported by our phylogenetic analysis. Conclusions Overall, we provide a comprehensive analysis of the rice SUMOylation machinery and discuss possible effects of the regulation of these genes at the transcriptional and post-transcriptional level. We also contribute to the characterization of two rice SUMO proteases, OsELS1 and OsFUG1. Electronic supplementary material The online version of this article (10.1186/s12870-018-1547-3) contains supplementary material, which is available to authorized users.

This study evaluated the metabolism of proline in rice based on the expression pattern of genes involved in biosynthesis and catabolism of amino acid and determined the correlation with the proline content produced under stress. In stage V4, genotypes with a differentiated response to salinity and low-temperature stresses were exposed separately to two test conditions: 150 mM NaCl and 13 °C. Proline increased in both genotypes and stresses. The expression of P5CS1 was increased in both genotypes and conditions, while P5CS2 was responsive in the sensitive genotype under salinity. High correlations between proline content/P5CS1, proline content/P5CS2, P5CS1/P5CR, and P5CS2/P5CR were observed for the tolerant genotype under salt stress. The correlation between proline content/PDH was 0.42 and −0.13 (tolerant genotype) and −0.54 and 0.15 (sensitive genotype) under salinity and cold, respectively. P5CDH was positively correlated with proline content under salinity for both genotypes. Under salt stress, there was a positive correlation between proline content/OAT in the tolerant genotype. It was concluded that the increase in proline content is greater for the tolerant genotype. Under salt stress, the levels of transcript genes are more correlated with the proline content in the tolerant genotype, while at 13 °C, the correlation of the sensitive genotype was higher.

The set of variables analyzed as integrated by multivariate analysis of principal components consistently showed a memory effect induced by the drought pre-treatment in AN Cambara plants. The effects of drought can vary ddepending on many factors. Among these the occurrence of a previous water stress may leave a residual effect (memory), influencing the future performance of a plant in response to a new drought event. This study tested the hypothesis that plants experiencing recurrent drought would show more active mechanisms of water deficit tolerance, mainly plants of the genotype that is cultivated often experiencing water shortages periods. Additionally, all the plants subjected to water deficit were rehydrated by 24 h and the expression of transcription factors related to drought responses was re-evaluated. To this end, the water status of two rice genotypes, BRS Querencia (flooded) and AN Cambara (dryland), was evaluated to identify molecular alterations likely underpinning drought-memory. In growth stage V5, some plants were exposed to water stress (10% VWC soil moisture—pre-treatment). Thereafter, the pots were rehydrated at the same level as the control pots and maintained under this condition until drought was reapplied (10% VWC) at the reproductive stage (R1–R2). Then, the plants were rehydrated and maintained at pot capacity for 24 h. Overall, the set of variables analyzed integrally by multivariate analysis of principal components consistently showed a memory effect induced by the drought pre-treatment in AN Cambara plants (the dryland genotype). This conclusion, based on data of the biochemical and molecular analyses, was supported by the greater capacity of maintenance of the water status by stomatal regulation of the pre-treated and rehydrated plants after the second drought stimulus.

Conyza bonariensis (hairy fleabane) is one of the most problematic and widespread glyphosate-resistant weeds in the world. This highly competitive weed species significantly interferes with crop growth and substantially decreases crop yield. Despite its agricultural importance, the molecular mechanisms of glyphosate resistance are still unknown. The present RNA-Seq study was performed with the goal of identifying differentially expressed candidate transcripts (genes) related to metabolism-based non-target site glyphosate resistance in C. bonariensis. The whole-transcriptome was de novo assembled from glyphosate-resistant and -sensitive biotypes of C. bonariensis from Southern Brazil. The RNA was extracted from untreated and glyphosate-treated plants at several timepoints up to 288 h after treatment in both biotypes. The transcriptome assembly produced 90,124 contigs with an average length of 777 bp and N50 of 1118 bp. In response to glyphosate treatment, differential gene expression analysis was performed on glyphosate-resistant and -sensitive biotypes. A total of 9622 genes were differentially expressed as a response to glyphosate treatment in both biotypes, 4297 (44.6%) being up- and 5325 (55.4%) down-regulated. The resistant biotype presented 1770 up- and 2333 down-regulated genes while the sensitive biotype had 2335 and 2800 up- and down-regulated genes, respectively. Among them, 974 up- and 1290 down-regulated genes were co-expressed in both biotypes. In the present work, we identified 41 new candidate target genes from five families related to herbicide transport and metabolism: 19 ABC transporters, 10 CYP450s, one glutathione S-transferase (GST), five glycosyltransferases (GT), and six genes related to antioxidant enzyme catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD). The candidate genes may participate in metabolic-based glyphosate resistance via oxidation, conjugation, transport, and degradation, plus antioxidation. One or more of these genes might &lsquo, rescue&rsquo, resistant plants from irreversible damage after glyphosate treatment. The 41 target genes we report in the present study may inform further functional genomics studies, including gene editing approaches to elucidate glyphosate-resistance mechanisms in C. bonariensis.

Submergence can affect plant development due to the stress of oxygen depletion. Another consequence of submergence is toxicity to plants by an excess soluble iron when the soil is under anaerobic conditions. Currently, much attention has been given to the role of ethylene response transcription factors (ERFs) family, especially when plants respond to conditions of oxygen depletion. Considering such a scenario, we aimed to evaluate the transcriptional response of seven ERF genes in leaves of rice seedlings subjected to conditions of anoxia (N2), hypoxia (submergence), and iron overload (2,000 mg L−1 of FeSO4.7H2O). All the analyzed genes showed differential transcriptional expression in response to these three stresses. Analyses in the promoter region of these transcription factors indicated that the promoter region closest to the transcription start site is most responsible for the differential response of these genes under conditions of oxygen absence (anoxia) or reduction (hypoxia). On the other hand, the promoter relationship was not detected for iron stress. The methylation of these regions as a mean of regulation is also suggested as well as the possibility of redundancy of different genes expressed at similar times and stressful conditions.

Rice (Oryza sativa L.) is one of the most important species for food production worldwide, besides being an excellent genetic model among the grasses. Cold is one of the major abiotic factors reducing rice yield, primarily affecting germination and reproduction phases. Currently, the RNAseq technique allows the identification of differential expressed genes in response to a given treatment, such as cold stress. In the present work, a transcriptome (RNAseq) analysis was performed in the V3 phase for contrasting genotypes Oro (tolerant) and Tio Taka (sensitive), in response to cold (13°C). A total of 241 and 244 M readings were obtained, resulting in the alignment of 25.703 and 26.963 genes in genotypes Oro and Tio Taka respectively. The analyses revealed 259 and 5579 differential expressed genes in response to cold in the genotypes Oro and Tio Taka respectively. Ontology classes with larger changes were metabolic process ~27%, cellular process ~21%, binding ~30% and catalytic activity ~22%. In the genotype Oro, 141 unique genes were identified, 118 were common between Oro and Tio Taka and 5461 were unique to Tio Taka. Genes involved in metabolic routes of signal transduction, phytohormones, antioxidant system and biotic stress were identified. These results provide an understanding that breeding for a quantitative trait, such as cold tolerance at germination, several gene loci must be simultaneously selected. In general, few genes were identified, but it was not possible to associate only one gene function as responsible for the cultivar tolerance; since different genes from different metabolic routes were identified. The genes described in the present work will be useful for future investigations and for the detailed validation in marker assisted selection projects for cold tolerance in the germination of rice.

Abiotic stresses caused by excessive cold, iron, and salt are among the main growth and yield-limiting factors of rice. Among the metabolic processes, photosynthesis stands out for being closely related to crop yields, causing a yield decline by reduced photosynthetic capacity in plants under abiotic stresses. The purpose of this study was to evaluate the differential expression of chloroplast genes involved in photosynthesis by RNA sequencing (RNA-seq) and quantify gas exchanges in leaves of rice plants exposed to cold, iron, and salt stress for 24 h. Of all genes expressed in each stress, cold had the highest number of differentially expressed genes (DEGs) related to light and chloroplast reactions, with 535 mostly down-regulated genes. Salt and iron stress was associated with 309 and 115 genes, respectively, involved in light reactions and chloroplast. The three stresses had transcripts with GOs related to light reactions, all with more than ten different GO terms. With regard to chloroplast, cold and salt stress had 12 terms of GO, and iron stress has 9 terms of GO. For gas exchange, only the parameter net assimilation rate differed significantly between stresses, with the lowest mean under cold stress. The results showed that cold stress affects photosynthesis most drastically, both at the molecular and the physiological level, and despite decreases in the net assimilation rate, changes under iron and salt stress were minor, which may be related to the tolerance of cultivar BRS Querencia.

Abiotic and biotic stress conditions cause extensive losses to maize production, mainly due to protein dysfunction in these conditions. In higher plants, the occurrence of heat-shock proteins (HSPs) in response to different environmental stresses is a universal phenomenon and has been well documented. Many studies have demonstrated that most HSPs are involved in many regulatory pathways, act as molecular chaperones for other cell proteins, and have strong cytoprotective effects. Although many functional roles for HSPs are known, the mechanisms for these multiple functions are not entirely understood. Here we reviewed the correlation among HSP genes/proteins and plant tolerance, especially maize, in different environmental stresses. Due to the low availability of information regarding the expression of HSP genes in response to different stresses in maize, we decided to mine databases in order to generate new insights related to this topic.

Stresses can cause large yield reductions in cultivated plants. The response to these stresses occurs via a plethora of signalling pathways, where a large number of genes is induced or repressed. Among the environmental stress responsive genes, there are the members of the ethylene response factors (ERF) gene family. The mRNA levels of different ERF are regulated by many hormones and molecules produced under different stress conditions. In this study, with the goal of identifying the response of rice ERF genes to environmental stress, it was analysed the transcriptional expression profile of 114 of these genes under stress by anoxia, salt and Magnaporthe grisea. Also, aiming to characterize how the regulation of ERF genes occurs, the amount of known cis regulatory elements in the promoter region of these genes and their association with the expression profiles under the tested conditions were also assessed. The results indicate that some ERF members present the same specific expression profiles under different environmental stresses, while others do not. Within the ERF family, the regulation of gene expression is complex for some genes which have many cis elements in their promoters, but simple for others, demonstrating high levels of divergence among them. The findings demonstrate the importance of the study of each ERF separately, since it is not possible to establish general rules for regulation and probably for the function of these genes.

Tomato (Solanum lycopersicum L.) is a climacteric fruit, i.e., during ripening an increase in ethylene synthesis and high rate of respiration are observed. Low oxygen levels might inhibit or block ethylene biosynthesis and therefore retard the ripening process. Despite commercial applications of low oxygen treatments, the precise mode of action of low oxygen in fruit tissues and ripening is not well understood. In order to delineate the molecular responses to low oxygen stress in fruits, hypoxia-responsive tomato genes encoding heat shock factors, heat shock proteins, and enzymes involved in fermentation and ethylene synthesis pathways were analyzed. In this study, tomato fruit stored under hypoxia conditions showed that HSP17.7 and HSP21 genes were highly induced by low oxygen level, indicating their primary role in maintaining cellular homeostasis after this stress.

Solos do tipo hidromórfico apresentam uma reduzida capacidade de drenagem, sendo utilizados principalmente para cultivo de arroz irrigado. Esta condição favorece o desenvolvimento de microrganismos anaeróbios que produzem substâncias fitotóxicas. O objetivo do trabalho foi avaliar a resposta de 25 genótipos de arroz ao ácido butírico, um composto produzido em solos de deficiente drenagem e alto teor de matéria orgânica. O trabalho foi executado em sistema de hidroponia com 4 doses do ácido e o delineamento utilizado foi blocos casualizados com 3 repetições em um esquema fatorial. As variáveis mensuradas foram comprimento de raízes (CR) e de parte aérea (CPA), número de raízes (NR) e matéria seca de raízes (MSR) e parte aérea (MSPA). Foram procedidas análise de variância, desempenho relativo e ajuste de regressões. Os efeitos para genótipos e doses de ácido butírico foram todos significativos. Apenas os efeitos de interação entre doses x genótipos para as variáveis CR e MSR revelaram significância. A variável CR foi a mais afetada pelo ácido e as regressões estabelecidas para essa variável revelaram 9 genótipos tolerantes e 16 sensíveis ao efeito fitototoxico do ácido butírico. Genótipos desenvolvidos para sistema de irrigação por inundação se mostraram mais tolerantes ao ácido. Hydromorphic soils have low drainage capacity and are used mainly for growing irrigated rice.. This condition favors the development of anaerobic microorganisms that produce phytotoxic substances. The objective of this work was to evaluate the response of 25 rice genotypes to butyric acid, a phytotoxic compound produced in low-drainage soils with high organic matter content. This work was performed by hydroponics with four acid doses as treatments using a random block design with three replications. The variables measured were root (CR) and shoot (CPA) length, number of roots (NR) and root (MSR) and shoot (MSPA) dry matter. Analysis of variance, relative performance and regression fitting were performed. Significance for genotype and dose was found for all variables. Significance for the interaction (genotype vs. dose) was found only for CR and MSR. The variable CR was the most influenced by the acid and the regression established for these variables revealed nine tolerant and 16 sensitive genotypes. Genotypes developed for irrigated systems were more tolerant.

Background The adverse environmental conditions impose extreme limitation to growth and plant development, restricting the genetic potential and reflecting on plant yield losses. The progress obtained by classic plant breeding methods aiming at increasing abiotic stress tolerances have not been enough to cope with increasing food demands. New target genes need to be identified to reach this goal, which requires extensive studies of the related biological mechanisms. Comparative analyses in ancestral plant groups can help to elucidate yet unclear biological processes. Results In this study, we surveyed the occurrence patterns of expressed sequence tag-derived microsatellite markers for model plants. A total of 13,133 SSR markers were discovered using the SSRLocator software in non-redundant EST databases made for all eleven species chosen for this study. The dimer motifs are more frequent in lower plant species, such as green algae and mosses, and the trimer motifs are more frequent for the majority of higher plant groups, such as monocots and dicots. With this in silico study we confirm several microsatellite plant survey results made with available bioinformatics tools. Conclusions The comparative studies of EST-SSR markers among all plant lineages is well suited for plant evolution studies as well as for future studies of transferability of molecular markers.