ABSTRACT Rice (Oryza sativa) is among the most important crops worldwide; however, rice crops demand high water consumption. Future projections indicate reduced water availability and severe drought events, which may affect rice crops as the cereal is highly sensitive to drought stress. Thus, cultivars with lower water demand for irrigation or drought escape capacities are among the strategies to address this issue. This study aimed to assess five mutant rice genotypes in terms of growth cycle length, other agronomic interest traits, and drought response in the reproductive stage. The mutant genotypes evaluated showed a shortening of the growth cycle compared to the original cultivar, BRS Pampeira, representing a drought escape strategy. In addition, mutations did not negatively affect plant height and crop yield. However, similar to the original cultivar, mutants are not tolerant to water deficit in the reproductive stage. The genotypes evaluated have potential to be released as early cycle cultivars, which can reduce water demand during the harvest season while presenting a drought escape strategy. Oryza sativa worldwide however consumption events stress Thus issue length traits stage cultivar Pampeira strategy addition yield However

Abstract The objective of this work was to map the chromosomal regions responsible for iron accumulation in rice grains, in Southern Brazil. Eighty-one rice accessions were genotyped and phenotyped for Fe accumulation. Single nucleotide polymorphisms were mapped in the whole grain on chromosomes 1, 5, 6, and 10, from which 13 candidate genes were identified. Some of the genes, such as O s10g040680 0, seem to have a relationship with Fe homeostasis, while others are related to other metabolic processes or have an unknown function.

Resumo O objetivo deste trabalho foi mapear regiões cromossômicas responsáveis pelo acúmulo de ferro em grãos de arroz, na região Sul do Brasil. Oitenta e um acessos de arroz foram genotipados e fenotipados quanto ao acúmulo de Fe. Polimorfismos de nucleotídeos únicos foram mapeados no grão integral, nos cromossomos 1, 5, 6 e 10, dos quais 13 genes candidatos foram identificados. Alguns dos genes, como o Os10g0406800, parecem ter relação com a homeostase do Fe, enquanto outros têm relação com outros processos metabólicos ou função desconhecida.

Abstract Effective strategies for disease control are crucial for sustaining world food production and ensuring food security for the population. Wheat blast, a disease caused by the pathogen Magnaporthe oryzae pathotype Triticum, has been a concern for cereal producers and researchers due to its aggressiveness and rapid expansion. To solve this problem, the development of resistant varieties with durable resistance is an effective, economical and sustainable way to control the disease. Conventional breeding can be aided by several molecular tools to facilitate the mining of many sources of resistance, such as R genes and QTLs. The identification of new sources of resistance, whether in the wheat crop or in other cereals are an opportunity for efficient wheat breeding through the application of different techniques. Since this disease is still poorly studied in wheat, knowledge of the rice Magnaporthe pathotype may be adapted to control wheat blast. Thus, genetic mapping, molecular markers, transgenic approaches, and genomic editing are valuable technologies to fight wheat blast. This review aimed to compile the biotechnological alternatives available to accelerate the development of improved cultivars for resistance to wheat blast. population blast Triticum expansion problem effective QTLs techniques Thus mapping markers approaches

Abstract Palm trees are the third most important botanical family for humans because of their potential use in oils, drugs, cosmetics, food, and feed. Despite their importance, little information on their genetics and molecular variations exists, and a better understanding could contribute to breeding programs. This study aimed to determine the amount, distribution, and organization of plastid simple sequence repeats (cpSSRs) and their potential use in breeding in 52 species belonging to the order Arecales. Plastid genomes were analyzed to identify cpSSRs according to their nature, position, and presence in genic or intergenic regions. Primer pairs were validated in silico for amplification and polymorphisms in these SSRs and their dissimilarities were evaluated. The results showed a high frequency of mononucleotide repeats in the intergenic regions. Approximately 76 primer pairs were generated and are suggested for further studies. The dissimilarity analysis of cpSSRs showed that mono- and trinucleotides were highly abundant in plastid SSRs.

ABSTRACT The olive tree (Olea europaea L.) is a species of great importance in history and economic, with large phenotypic variability, represented through a wide range of cultivars spread throughout the world. There are several studies on the characterization of a large number of cultivars of the species. However, there is a need to uncover how these phenotypic traits are heritable, and how they can change when environmental conditions vary. For this reason, the objective here was to estimate the heritability coefficients for fruit characters in six commercial cultivars, analyzed under conditions in the state of Rio Grande do Sul, Brazil. The study was carried out in a single year, based on the analysis of fruit and oil traits on the cultivars Arbequina, Arbosana, Frantoio, Koroneiki, Manzanilla de Sevilla, and Picual, under environmental conditions in the state of Rio Grande do Sul. Phenotypic plasticity and broad-sense heritability were estimated in both inter and intra-cultivar comparisons. From the analyses of variance and heritability, it was observed that some cultivars such as Koroneiki or Picual had their characters mainly under genetic control, while Arbequina was more influenced by genotype-environment interaction. The information derived from this work can help guide the selection of cultivars that are best adapted under the local environments of the southern region of Brazil.

Abstract: Rice blast, caused by the fungus Pyricularia oryzae L., is considered one of the main threats to world rice production. The development of resistant cultivars is one of the best and sustainable control alternatives. Plant breeding efforts have been accelerated by genetic mapping (linkage and associative) and marker assisted selection. On the other hand, genomic editing techniques, such as meganucleases (MNs), Zinc-finger nucleases (ZFNs), Transcription Activator-like Effector Nucleases (TALENs) and Clustered Regularly Interspaced Short Palindrome Repeats/CRISPR-associated protein 9 (CRISPR/Cas9), can be used to promote specific genetic modifications. Likewise, transgenics can also be used to manipulate specific genes. In this sense, this work aims to characterize rice blast and elucidate available biotechnological alternatives to accelerate the development of improved rice cultivars resistant to rice blast.

Abstract There is a worldwide concern about a possible narrowing of the genetic base of most crops, as e.g. that of rice (Oryza sativa L.), as a result of the modern breeding practices. Thus, the purpose of this study was to investigate this phenomenon in the germplasm of elite paddy rice in southern Brazil, including frequently used accessions in crosses. The panel consisted of 91 accessions. Data of morphological traits, SNP markers and mineral content of husked and polished grain were analyzed by hierarchical clustering and principal component analysis. The SNP markers and hierarchical clustering proved most appropriate to assess the genetic variability. A narrowing of the genetic base of rice was confirmed, although a certain level of genetic variability was still found in the germplasm of elite paddy rice in south Brazilian rice, particularly for grain mineral content.

Resumo: O objetivo deste trabalho foi comparar o uso de métodos biométricos uni e multivariados na avaliação da adaptabilidade e da estabilidade de um importante grupo de cultivares de aveia-branca (Avena sativa), cultivadas no Sul do Brasil. Utilizou-se o delineamento experimental de blocos ao acaso, em arranjo fatorial 12 ambientes x 7 cultivares, com três repetições. A análise de variância e os métodos de Eberhart & Russel, de Annicchiarico e da média harmônica do desempenho relativo dos valores genéticos preditos (MHPRVG) foram avaliados. Na comparação geral dos métodos, os genótipos 'UPFA Gaudéria' e 'URS Guapa' foram os mais estáveis em relação à produtividade de grãos. Os genótipos 'UPFA Gaudéria' e 'URS-21' destacaram-se em peso do hectolitro, tendo apresentado as melhores respostas pelo método de Annicchiarico e da MHPRVG. Para a massa de mil grãos, todos os métodos apresentaram resultados semelhantes, o que indica que o genótipo 'UPFA Gaudéria' apresentou os melhores resultados. O genótipo 'URS Guapa' foi superior quando foram utilizados os métodos de Eberhart & Russel, de Annicchiarico e da MHPRVG. Os métodos uni e multivariados avaliados são adequados para estimar com confiança a adaptabilidade e a estabilidade das cultivares para cada objetivo de produção, rendimento e qualidade de grãos.

Abstract: The objective of this work was to compare uni- and multivariate biometric methods to evaluate the adaptability and stability of an important group of white oat (Avena sativa) cultivars grown in Southern Brazil. The used experimental design was a randomized complete block, in a factorial arrangement of 12 environments x 7 cultivars, with three replicates. The analysis of variance and the methods of Eberhart & Russel, Annicchiarico, and the harmonic mean of the relative performance of predicted genetic values (MHPRVG) were assessed. In the general comparison of the methods, the 'UPFA Gaudéria' and 'URS Guapa' genotypes were more stable regarding grain yield. The 'UPFA Gaudéria' and 'URS-21' genotypes stood out for hectoliter weight, presenting the best performances by the methods of Annicchiarico and the MHPRVG. For thousand-grain weight, all methods showed similar results, indicating that the 'UPFA Gaudéria' genotype presented the best results. The 'URS Guapa' genotype was superior when using the methods of Eberhart & Russel, Annicchiarico, and the MHPRVG. The uni- and multivariate methods evaluated are suitable to estimate with high confidence the adaptability and stability of cultivars for each targeted grain production, yield, and quality.

Resumo: O objetivo deste trabalho foi avaliar o desempenho de híbridos de milho (Zea mays) intervarietais, a partir de cruzamentos topcross entre populações crioulas, além de confirmar se a dissimilaridade genética entre as populações é correlacionada à heterose dos híbridos intervarietais no campo. Nove híbridos topcross foram avaliados com seu testador 'BRS Planalto', e as seguintes populações crioulas foram utilizadas como genitores: Argentino Branco, Dente de Ouro, Amarelão, Criolão, Caiano Rajado, Branco Oito Carreiras, Branco Roxo Índio, Cateto Branco e Argentino Amarelo. O testador 'BRS Planalto' e os híbridos topcross Branco Oito Carreiras x 'BRS Planalto' e Criolão x 'BRS Planalto' apresentaram maior potencial per se quanto ao rendimento de grãos. O topcross Branco Oito Carreiras x 'BRS Planalto' apresentou melhor desempenho quanto a número de grãos por fileira, massa de grãos da espiga e diâmetro de espiga, enquanto o Criolão x 'BRS Planalto' apresentou melhor desempenho quanto a número de grãos por fileira e comprimento de espiga. As maiores estimativas de distância genética não implicaram, necessariamente, altos valores de heterose, e tiveram correlação apenas com o comprimento da espiga. Portanto, não é possível predizer os efeitos de alta heterose sobre o rendimento de grãos, com base na distância genética entre as populações envolvidas nos cruzamentos.

Abstract: The objective of this work was to evaluate the performance of intervarietal corn (Zea mays) hybrids with topcross crosses between landrace populations, and to confirm whether genetic dissimilarity between populations is correlated with the heterosis of the intervarietal hybrids in the field. Nine topcross hybrids were evaluated with their tester 'BRS Planalto', and the following landrace populations were used as parents: Argentino Branco, Dente de Ouro, Amarelão, Criolão, Caiano Rajado, Branco Oito Carreiras, Branco Roxo Índio, Cateto Branco, and Argentino Amarelo. The tester 'BRS Planalto' and the topcross hybrids Branco Oito Carreiras x 'BRS Planalto' and Criolão x 'BRS Planalto' showed higher per se potential for grain yield. The topcross hybrid Branco Oito Carreiras x 'BRS Planalto' showed a better performance for number of grains per row, grain weight, and ear diameter, whereas Criolão x 'BRS Planalto' displayed a better performance for the number of grains per row and ear length. Greater estimates of genetic distance did not necessarily result in greater heterosis values and were exclusively correlated with grain ear length. Therefore, it is not possible to predict the effects of high heterosis on grain yield, based on the genetic distance between the populations involved in the crosses.

Abstract WRKY transcription factors (TFs) are responsible for the regulation of genes responsive to many plant growth and developmental cues, as well as to biotic and abiotic stresses. The modulation of gene expression by WRKY proteins primarily occurs by DNA binding at specific cis-regulatory elements, the W-box elements, which are short sequences located in the promoter region of certain genes. In addition, their action can occur through interaction with other TFs and the cellular transcription machinery. The current genome sequences available reveal a relatively large number of WRKY genes, reaching hundreds of copies. Recently, functional genomics studies in model plants have enabled the identification of function and mechanism of action of several WRKY TFs in plants. This review addresses the more recent studies in plants regarding the function of WRKY TFs in both model and crop plants for coping with environmental challenges, including a wide variety of abiotic and biotic stresses.

Abstract Iron is a well-known metal. Used by humankind since ancient times in many different ways, this element is present in all living organisms, where, unfortunately, it represents a two-way problem. Being an essential block in the composition of different proteins and metabolic pathways, iron is a vital component for animals and plants. That is why iron deficiency has a severe impact on the lives of different organisms, including humans, becoming a major concern, especially in developing countries where access to adequate nutrition is still difficult. On the other hand, this metal is also capable of causing damage when present in excess, becoming toxic to cells and affecting the whole organism. Because of its importance, iron absorption, transport and storage mechanisms have been extensively investigated in order to design alternatives that may solve this problem. As the understanding of the strategies that plants use to control iron homeostasis is an important step in the generation of improved plants that meet both human agricultural and nutritional needs, here we discuss some of the most important points about this topic.

ABSTRACT Drought stress affects crop quality and productivity. The challenge of increasing food availability for a growing worldwide demand relies on the development of tolerant cultivars that will need to be adapted to arid and semi-arid areas. In order to help the understanding of rice response to stress, the phenotypic response of 6 Brazilian rice cultivars and 2 different crosses between them were characterized under drought conditions. Since gene regulation is an important part of root morphological responses to stressful conditions, 4 genes related to auxin response and root modifications (OsGNOM1 CRL4, OsIAA1, OsCAND1 and OsRAA1) were evaluated. The expression of these genes was analyzed in stressed rice using public available microarray data and then through real-time quantitative polymerase chain reaction (RT-qPCR), in the 6 phenotypically evaluated Brazilian genotypes under standard conditions (absence of stress). Our results show that all genotypes lengthened its roots in response to drought, specially the 2 hybrids. The expression of these genes is modified in response to stress, and OsRAA1 has a very special behavior, constituting a target for future studies. Further steps include the study of polymorphisms in these genotypes in order to understand if differences in these genes or in regulatory regions can be associated with differences in root system architecture and/or stress tolerance.

ABSTRACT Improvement of quality-related traits of grains is a constant concern in white oat breeding programs, which challenges breeders to understand their dynamics. The performance of different genetic combinations must be thoroughly evaluated to make high nutritional quality cultivars available. This study aimed to estimate the heterosis on F1 and F2 generations, vigor loss, due to inbreeding, and correlation between the grain chemical components to understand the dynamics of these traits, considering two segregating oat progenies. The populations Albasul × UPF 15 (population 1) and IAC 7 × UFRGS 19 (population 2) were developed. Both populations showed transgressive segregant individuals. The combination Albasul × UPF 15 provided significant heterosis for traits β-glucan total and soluble fiber contents, while the population obtained by crossing IAC 7 × UFRGS 19 generated significant gain by heterosis for total fiber, insoluble fibers and non-structural carbohydrate contents. Considering the F2 average for each population, one can observe that population 1 presents higher β-glucan and lipid contents than population 2. On the other hand, population 2 has higher protein content than population 1. In both populations, the non-structural carbohydrate content is strongly and negatively correlated whith protein, total and insoluble fibers. Correlations between total fibers and lipids and between total fibers and insoluble fibers were both positive and high in both populations.

ABSTRACT O incremento do potencial produtivo nas novas variedades de arroz (Oryza sativa L.) tem sido um dos principais desafios para o melhoramento genético. A geração de mutantes, seguida da sua caracterização, constitui-se em uma ótima possibilidade para isolar e selecionar genes e genótipos que apresentem caracteres agronômicos de interesse. Este trabalho teve como objetivo avaliar o efeito do mutagênico químico etilmetanossulfonato (EMS) sobre caracteres agronômicos em 340 famílias M3 de arroz, derivadas da cultivar BRS Querência. As sementes de cada família e da testemunha BRS Querência foram semeadas a campo e posteriormente avaliadas para os caracteres comprimento da panícula principal, peso da panícula principal, massa de grãos da panícula principal, largura da folha bandeira e estatura de planta. Os dados foram submetidos à análise de variância (p ≤ 0,05), e a comparação entre as médias foi realizada pelo teste de Dunnett a 5% de significância. Os resultados obtidos mostram que existe variabilidade genética entre as famílias mutantes de arroz e que a indução de mutação com EMS a 1,5% é eficiente na geração de mutantes de arroz para todos os caracteres avaliados. Dentre esses, a estatura das plantas foi a mais afetada pelo agente mutagênico, o qual proporcionou o incremento do caráter. Para o caráter comprimento da panícula principal, sete famílias obtiveram médias superiores à testemunha; já para os caracteres peso e massa de grãos da panícula principal, foram observadas quatro e seis famílias mutantes, respectivamente, com desempenho superior ao da testemunha.

ABSTRACT The increase of yield potential in new rice (Oryza sativa L.) varieties has been a major challenge for genetic improvement. The generation of mutants, followed by their characterization, constitutes a great possibility to isolate and select genes and genotypes that present agronomic traits of interest. This study aimed to evaluate the effect of chemical mutagen ethyl methane sulphonate (EMS) on agronomic traits in 340 M3 families of rice derived from BRS Querência cultivar. Seeds from each family and the original genotype BRS Querência were sown in the experimental field, and the characters main panicle length, main panicle weight, main panicle grain weight, flag leaf width and plant height were evaluated. Data were subjected to analysis of variance (p ≤ 0.05), and a comparison of means was carried out by Dunnett's test at 5% significance. The results show that there is genetic variability among the mutant families, suggesting that the mutagen EMS at 1.5% is effective for generating mutants for all assessed traits. Among the characters, plant height was the most affected by the mutagen, which provided an increase in the character. For the main panicle length character, seven families showed means above the control; for main panicle weight and grain weight, four and six mutant families were observed, respectively, with a superior performance in comparison to the control.

Observando as novas demandas do cenário agrícola mundial, a busca por genótipos mais produtivos, eficientes e adaptados a estresses tem chamado a atenção de melhoristas de plantas na análise de plantas com melhores características fisiológicas. Nesse contexto, o caráter stay-green vem tomando destaque, como uma importante estratégia em superar os atuais tetos de produtividade, aliados à adaptabilidade e estabilidade. Esta revisão tem com objetivo trazer à luz os principais aspectos relacionados ao caráter stay-green, mostrando suas potencialidades de emprego no melhoramento genético de plantas.

Looking at the new demands of the global agricultural scenario, the search for more productive, efficient and stress adapted genotypes has attracted attention of plant breeders regarding plants with improved physiological characteristics. Therefore, the stay-green trait has taken proeminence as an important strategy to overcome the current yield plateaus allied with yield adaptability and stability. This review has aimed to bring light the main aspects of the stay-green character, showing their employment potential of plant breeding.