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

Resumo O objetivo deste trabalho foi caracterizar a tolerância ao frio em famílias mutantes de arroz na geração M4, no início do estágio vegetativo. Foram realizados dois experimentos. No experimento I, a tolerância ao frio foi avaliada em 43 famílias mutantes, no genótipo original 'BRS Querência' e em 19 genótipos comerciais. No Experimento II, 8 famílias mutantes do Experimento I, 'BRS Querência' e um mutante proveniente da geração M5 foram testados. Em ambos os experimentos, as plântulas foram avaliadas em duas condições: 10°C por sete dias e 25°C por sete dias. No Experimento I, as mutações induzidas em arroz levaram a respostas variadas nas características de tolerância ao frio, com algumas famílias mutantes M4 tendo superado o genótipo original. O Experimento II destacou o impacto das mutações na tolerância ao frio, particularmente em termos de descoloração das folhas e recrescimento da planta. As famílias mutantes no estágio M4 diferem do genótipo original 'BRS Querência' em tolerância ao frio, no início do estágio vegetativo. As famílias mutantes M36, M54 e M56 e 'BRS Querência' apresentam similaridade genética, o que indica falta de tolerância ao frio durante o início do estágio vegetativo. As famílias mutantes M17, M21, M22 e M26 são promissoras para programas de melhoramento genético de arroz, pois apresentam tolerância ao frio. A família mutante M30 apresenta o melhor desempenho em todas as características analisadas, o que indica tolerância ao frio no início do estágio vegetativo. M vegetativo experimentos I 4 BRS Querência 1 comerciais testados condições 10C C 10 25C 25 planta M36 genética M17 M21 M2 M3 analisadas 2 M1

Abstract The objective of this work was to characterize chilling tolerance in rice mutant families of the M4 generation, at the seedling stage. Two experiments were carried out: chilling tolerance was evaluated in 43 mutant families, in the 'BRS Querência' original genotype, and in 19 commercial genotypes. In Experiment II, 8 mutant families from Experiment I, 'BRS Querência', and a mutant of the M5 generation were tested. In both experiments, seedlings were evaluated under two conditions: 10°C for seven days and 25°C for seven days. In Experiment I, the induced mutations in rice led to varied responses in chilling tolerance traits, with some M4 mutant families outperforming the original genotype. Experiment II highlighted the impact of mutations on chilling-tolerance, particularly in terms of leaf discoloration and plant recovery. Mutant families of the M4 generation differ from the original genotype 'BRS Querência' in chilling tolerance at the seedling stage. The mutant families M36, M54, and M56 and 'BRS Querência' show genetic similarity, indicating a lack of chilling tolerance during the seedling stage. The mutant families M17, M21, M22, and M26 are promising for rice breeding programs because they present chilling tolerance. The M30 mutant family exhibits the best performance for all analyzed traits, indicating chilling tolerance at the seedling stage. M stage out 4 BRS Querência 1 genotypes I Querência, , tested conditions 10C C 10 25C 25 traits chillingtolerance, chillingtolerance tolerance, chilling-tolerance recovery M36 M54 similarity M17 M21 M22 M2 M3 2 M1

Abstract This study aimed to select recombinant lines and explore phenotypic and genotypic correlations using BLUP. It was conducted in Capão do Leão/RS during two years, in an incomplete block design with intercalary controls, with four replications. 131 and 128 RILs were tested in the F6 in the F7 generations, respectively. Plant height; days to flowering; panicle length; number of panicles per plant; number of fertile and sterile spikelets per panicle; one hundred grains weight; yield per plant; broken, chalky, white-belly and red-streaked grains; vitreous whiteness; gelatinization temperature; and apparent amylose content were obtained. According to the study, line F105 is an elite line for improving grain quality, exhibiting high amylose content (27.041%). Canonical (r=0.817), phenotypic (0.541) and genotypic (0.808) correlations inferred that groups of grain quality and agronomic traits were not independent and there was a tendency for the amylose content to be associated with grain yield. BLUP LeãoRS Leão RS years controls replications 13 12 F generations respectively height flowering length plant weight broken chalky whitebelly white belly redstreaked red streaked whiteness temperature obtained F10 27.041%. 27041 27.041% . 27 041 (27.041%) r=0.817, r0817 r r=0.817 , 0 817 (r=0.817) 0.541 0541 541 (0.541 0.808 0808 808 (0.808 1 F1 2704 27.041 2 04 (27.041% r081 r=0.81 81 (r=0.817 0.54 054 54 (0.54 0.80 080 80 (0.80 270 27.04 (27.041 r08 r=0.8 8 (r=0.81 0.5 05 5 (0.5 0.8 08 (0.8 27.0 (27.04 r0 r=0. (r=0.8 0. (0. 27. (27.0 r=0 (r=0. (0 (27. r= (r=0 ( (27 (r= (2 (r

Resumo O objetivo deste trabalho foi determinar as correlações genéticas e as associações diretas e indiretas de caracteres agronômicos e atributos de qualidade de grãos com a percentagem de grãos inteiros em arroz irrigado por inundação. O experimento foi conduzido em dois ambientes, em delineamento de blocos ao acaso, com três repetições, tendo-se utilizado 23 genótipos de arroz irrigado. Os caracteres avaliados foram: percentagem de grãos inteiros, comprimento da cariopse, largura da cariopse, comprimento da panícula, peso da panícula, peso de mil grãos, dias para floração, percentagem de grãos com “barriga branca” e grãos gessados, área gessada total, brancura total, brancura vítrea e defeitos de coloração. A percentagem de grãos com “barriga branca” e área gessada total correlacionaram-se positivamente, enquanto a percentagem de grãos com “barriga branca” e gessada e brancura vítrea correlacionaram-se negativamente. Os caracteres largura da cariopse, percentual de grãos com “barriga branca” e gessada, peso da panícula e peso de mil grãos apresentaram efeitos indiretos sobre a resposta de rendimento de grãos inteiros de acordo com área total gessada e brancura total. Área total gessada e brancura total são os fatores que mais influenciam negativamente a percentagem de grãos inteiros de acordo com as correlações genotípicas e os efeitos diretos. inundação ambientes acaso repetições tendose tendo se 2 foram cariopse floração barriga branca gessados coloração correlacionaramse correlacionaram positivamente diretos

Abstract The objective of this work was to determine the genetic correlations and the direct and indirect associations of agronomic traits and grain quality attributes with the percentage of whole grains in flood irrigated rice. The experiment was carried out in two environments, in a randomized complete block design with three replicates, using 23 irrigated rice genotypes. The evaluated traits were: percentage of whole grains, caryopsis length, caryopsis width, panicle length, panicle weight, 1,000 grain weight, days to flowering, percentage of chalky grains with white belly, total chalky area, total whiteness, vitreous whiteness, and defects in coloring. The percentage of grains with white belly and total chalky area were positively correlated, whereas the percentage of grains with white belly and vitreous whiteness were negatively correlated. The traits caryopsis width, percentage of chalky grains with white belly, panicle weight, and 1,000 grain weight showed indirect effects on whole-grain yield response according to total chalky area and total whiteness. Total chalky area and total whiteness are the factors that most negatively influence the percentage of whole grains according to the genotypic correlations and direct effects. environments replicates 2 genotypes length width 1000 1 000 1,00 flowering coloring correlated wholegrain 100 00 1,0 10 0 1,

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. Brasil Fe integral 1 5 10 identificados Os10g0406800 Osg Os g desconhecida Os10g040680 Os10g04068 Os10g0406 Os10g040 Os10g04 Os10g0 Os10g

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. grains Brazil Eightyone Eighty one 1 5 6 10 identified sg s g s10g04068 0 homeostasis function s10g0406 s10g040 s10g04 s10g0 s10g

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 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.

Resumo O objetivo deste trabalho foi analisar componentes de variâncias e herdabilidades, estimar o ganho de seleção e avaliar as diferentes pressões de seleção para atributos físicos de qualidade de grãos de famílias de gerações segregantes de arroz (Oryza sativa) irrigado, por meio da metodologia REML/BLUP. O experimento foi conduzido no Rio Grande do Sul, Brasil, onde foram realizadas seleções nas gerações segregantes F3, F4 e F5, nas safras 2015/2016, 2016/2017 e 2017/2018, em oito populações segregantes (famílias) oriundas de diferentes cruzamentos. Foram avaliados atributos físicos de qualidade intrínsecos, parâmetros genéticos e resposta à seleção, tendo-se utilizado diferentes pressões de seleção. Foram obtidas estimativas que apresentaram ganhos genéticos para os caracteres de qualidade dos grãos, principalmente para área calcárea total, alvura vítrea, alvura total, relação entre alvura vítrea e alvura total, e percentual de grãos inteiros e quebrados, em seleções nas primeiras gerações. As famílias utilizadas apresentam resultados satisfatórios, sendo superiores às cultivares-controle. Para a maioria dos caracteres, as estimativas de herdabilidade em sentido amplo são consideradas intermediárias, junto com os demais parâmetros, o que mostra a possibilidade de seleção genética para os atributos de qualidade do grão. A resposta à seleção com pressão de 10% é muito promissora para os atributos de qualidade de grãos de arroz.

Abstract The objective of this work was to analyze components of variances and heritabilities, estimate selection gain, and evaluate the different selection pressures for physical quality attributes of grains of families of segregating generations of irrigated rice (Oryza sativa), through the REML/BLUP methodology. The experiment was conducted in the state of Rio Grande do Sul, Brazil, where selections were made in the F3, F4, and F5 segregating generations, in the 2015/2016, 2016/2017, and 2017/2018 crop seasons, in eight segregating populations (families) from different crosses. Intrinsic physical quality attributes, genetic parameters, and response to selection were evaluated using different selection pressures. The obtained estimates showed genetic gains for the characters related to grain quality, mainly for total chalky area, vitreous whiteness, total whiteness, ratio between vitreous whiteness and total whiteness, and percentage of whole grains and broken grains, in selections in early generations. The used families show satisfactory results, being superior to the control cultivars. For most characters, the estimates of broad-sense heritability are considered intermediate, together with the other parameters, showing the possibility of genetic selection for grain quality attributes. The response to selection with a pressure of 10% is very promising for rice grain quality attributes.

ABSTRACT Biochemical assays in a time-course were employed to evaluate stresses induced by glyphosate treatment in resistant and sensitive biotypes of Conyza bonariensis. Two experiments were conducted assessing glyphosate doses and time-course after treatment. The doses of glyphosate ranged from 0 to 11840 g ae·ha–1 and assessments performed until 552 h after glyphosate treatment (HAT). The objectives of this study were to evaluate the oxidative stress and differential antioxidant enzyme activity in glyphosate-resistant and -sensitive biotypes of hairy fleabane after glyphosate treatment. After treatment, both studied biotypes accumulated similar levels of shikimic-acid until 96 h. The sensitive biotype died at192 HAT. Shikimic-acid and hydrogen peroxide (H2O2) accumulation in glyphosate-resistant biotype were transient and did not differ from untreated plants at 288 and 500 HAT, respectively. In both glyphosate-resistant and -sensitive biotypes, a correlation analysis established a cause-and-effect relationship after glyphosate treatment, which leads to shikimic-acid and hydrogen peroxide accumulation, lipid peroxidation (indicates tissue damage) and an enhancement in the activity of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzyme. However, in the glyphosate-resistant biotype, the oxidative stress and tissue damage were lower, and antioxidant enzyme activities SOD, CAT, and APX were higher than in the -sensitive biotype. It indicates that antioxidant enzyme in glyphosate-resistant biotype might be related to the glyphosate-resistance process in Conyza bonariensis. This study is the first report of differential antioxidant enzyme activity in hairy fleabane.

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.

Resumo: O objetivo deste trabalho foi avaliar a consistência dos métodos de Annicchiarico, Lin & Binns, Wricke e de análise fatorial na identificação de clones de eucalipto com estabilidade, adaptabilidade e alto potencial produtivo. Foram utilizados 84 clones, com três anos de idade, provenientes do programa de melhoramento genético da empresa CMPC Celulose Riograndense. Três experimentos de campo foram realizados em delineamento de blocos ao acaso, em arranjo fatorial 84x3, com 20 repetições de uma planta por parcela. Os clones foram avaliados quanto a diâmetro à altura do peito, altura da planta e volume de madeira. Os métodos de Annicchiarico e Lin & Binns são altamente correlacionados entre si, e seu uso em conjunto com o método de Wricke é uma estratégia apropriada para avaliação de clones de eucalipto. A análise fatorial identificou clones amplamente adaptáveis, e alguns deles foram os mesmos identificados pelos métodos de Annicchiarico e Lin & Binns. O uso da classificação média dos clones, juntamente com a análise fatorial, é eficiente para identificar os mais adaptados, estáveis e produtivos, entre um elevado número de genótipos.

Abstract: The objective of this work was to evaluate the consistency of the methods of Annicchiarico, Lin & Binns, Wricke, and factor analysis in identifying eucalyptus clones with stability, adaptability, and high productive potential. Eight-four clones, with three years of age, from the genetic breeding program of the company CMPC Celulose Riograndense were used. Three field experiments were carried out in a randomized complete block design, in an 84x3 factorial arragement, with 20 replicates of one plant per plot. The clones were evaluated as to diameter at breast height, plant height, and volume of wood. The methods of Annicchiarico and Lin & Binns are highly correlated with each other, and their use together with the method of Wricke is a sound strategy for the evaluation of eucalyptus clones. The factor analysis identified broadly adaptable clones, and some of them were the same ones identified by the methods of Annicchiarico and Lin & Binns. The use of the mean classification of the clones, along with the factor analysis, is efficient to identify the most adapted, stable, and productive ones among a high number of genotypes.

RESUMO: O caráter stay-green tem sido relacionado à maior tolerância a estresses e a produtividade pela manutenção mais prolongada do aparato fotossintético. A relação deste caráter com a produtividade de grãos talvez esteja associada a uma rede de características que não somente a massa de grãos. O objetivo do estudo é trazer à luz a real contribuição do caráter stay-green em trigos brasileiros, na relação entre os caracteres definidores da produtividade de grãos, em diferentes condições de ambiente. O experimento foi conduzido em delineamento experimental de blocos casualizados com três repetições, nos anos de 2003, 2004 e 2005. Foram avaliadas linhagens-irmãs com presença e ausência do caráter stay-green, analisando a correlação fenotípica e trilha separadamente por ano e grupo de maturação. Em condições favoráveis de cultivo, a contribuição do caráter stay-green em trigo se dá pelo aumento da fertilidade de espiga, incrementando o número de grãos. Num cenário mais restritivo, favorece a massa de grãos pelo maior tempo de enchimento no final do ciclo.

ABSTRACT: The stay-green character has been related to greater stress tolerance and yield through longer activity of the photosynthetic apparatus. Association of this character with grain yield may be linked to a network of features other than the grain mass. This study aimed to shed light on the actual contribution of stay-green character in Brazilian wheats and the associations between grain yield components in different environmental conditions. The experiment was conducted in a randomized block design with three replications in the years 2003, 2004 and 2005. Sibling lines with and without the stay-green character were evaluated analyzing the phenotypic correlation and path analysis separately by year and maturity group. Under favorable growing conditions, the contribution of stay-green character in wheat is obtained by the increased ear fertility and number of grains. In a more restrictive scenario, it favors an increase in grain mass by longer filling time at the end of the cycle.

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.