Prospecção de genes candidatos ao deficit hídrico em soja
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2022-09-09
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Universidade Federal de Viçosa
Resumo
A soja é a principal oleaginosa cultivada mundialmente, e contribui tanto para a alimentação humana quanto para à animal. Devido essa grande importância, grandes esforços são realizados para o desenvolvimento de novas cultivares. Contudo, condições adversas, como períodos de escassez hídrica, tem se tornado cada vez mais frequentes com o avanço das mudanças das condições climáticas. Esses períodos causam grandes perdas nas culturas, na soja perdas de 24 - 50% têm sido registrados. Assim, muitos estudos têm focado nas fases críticas da soja, no entanto, o período de estiagem pode ocorrer durante qualquer fase da cultura. Assim no intuito de ajudar a compreender esse processo complexo e auxiliar no desenvolvimento de cultivares mais tolerantes, esse estudo tem os seguintes objetivos: (i) identificar os marcadores moleculares e os genes candidatos associados à estes marcadores no processo de tolerância ao déficit hídrico em soja durante o estádio de germinação; (ii) identificar os marcadores moleculares e os genes candidatos associados à estes marcadores no processo de tolerância ao déficit hídrico em soja durante o estádio vegetativo. Em cada estádio foram realizados dois experimentos em delineamento em blocos casualizados em esquema fatorial 100 x 2 (Genótipos x Disponibilidade hídrica) com 3 repetições. Os cultivares utilizados, foram provenientes de diversas empresas comerciais a fim de representar um painel de diversidade de soja no país. As disponibilidades hídricas foram: a condição controle (Capacidade de campo) e a condição estresse ( -0,2 MPa (germinação) ou -1,2 MPa (estádio vegetativo)) com duração de 20 dias. A parcela experimental no estádio de germinação foi uma linha contendo dez sementes tratadas e no estádio vegetativo foi uma planta em um vaso de 3 litros de substrato (solo:areia). O início do período de estresse na germinação foi no ato do plantio das sementes, enquanto no vegetativo foi quando as plantas entraram no estádio vegetativo 2 (V2). Para cada característica foram obtidos os valores genotípicos (gBLUP) utilizando duas abordagens para o conceito de tolerância. Na primeira abordagem utilizou-se a diferença entre a condição estresse e a controle para obter o valor genotípico. Na segunda abordagem os gBLUPs foram obtidos utilizando os dados da condição estresse e controle como tratamentos. Os valores de gBLUP foram então utilizados no estudo de associação genômica ampla para a obtenção dos marcadores significativos. No estádio vegetativo foram identificados 25 marcadores do tipo SNP utilizando a primeira abordagem e 18 marcadores utilizando a segunda. Dentre esses, 3 marcadores estavam presentes em ambas as abordagens. Foram encontrados 5 genes na região próxima a esses marcadores em que: um relacionado a parede celular, dois relacionados a transporte de proteínas e dois fatores de transcrição. No estádio vegetativo, foram encontrados 114 marcadores na primeira abordagem e 68 na segunda. Em ambas as abordagens foram encontrados 18 marcadores moleculares. Na região próxima a esses marcadores foram encontrados 15 genes: um fator de transcrição, quatro que já são relacionados à tolerância ao déficit hídrico, três relacionados ao crescimento de raízes e seis que são relacionados a outros tipos de estresse. Palavras-chave: Glycine max. Estresse abiótico. GWAS. Germinação. Estádio vegetativo. Melhoramento de plantas.
Soybean is the major oilseed crop grown worldwide and contributes to both human and animal nutrition. Due to its great importance, great efforts are made to develop new productive cultivars. However, though conditions, such as drought, have become more frequent with the climatic changes. These periods have caused great losses in crops, in soybean losses of 24 - 50% had recorded. Thus, many studies have focused on the critical phases of soybeans, however, the dry period can occur during any phase of the crop. Thus, for understanding this complex process and assist the development of tolerant cultivars, this study aims: (i) identify molecular markers and candidate genes associated with these markers in the process of tolerance to water deficit in soybean during the germination stage; (ii) identify molecular markers and candidate genes associated with these markers in the process of tolerance to water deficit in soybean during the vegetative stage. At each stage, it carried out two experiments in a randomized block design with 3 replications in a 100 x 2 factorial (Genotypes x Water availability). The cultivars, became from different companies, representing country's soybean diversity panel. The water availability was: the control condition (Field capacity) and the stress condition (-0.2 MPa (germination) and -1.2 MPa (vegetative stage)) with a duration of 20 days. The experimental plot at the germination stage was a row containing ten treated seeds and at the vegetative stage, it was a plant in a 3-liter pot of substrate. The substrate used in germination was sand, and in the vegetative stage, it was a mixture of soil and sand. For the germination stage, the stress period began at the time of planting the seeds, while the vegetative period was when the plants entered the vegetative stage 2 (V2). For each trait, genotypic values (gBLUP) were obtained using two approaches to the concept of tolerance. The first approach used the difference between the stress condition and the control to obtain the genotypic value. In the second approach, gBLUP values were obtained using data from stress and control conditions as treatments. The gBLUP values were then used in genome-wide association studies to obtain significant markers. At the germination stage, 25 SNP-type markers were significant using the first approach and 18 markers using the second. Among these, three markers were present in both approaches. In the region close to those three markers, are five genes: one related to the cell wall, two related to protein transport, and two transcription factors. At the vegetative stage, 114 markers were significant in the first approach and 68 in the second approach. In both approaches, it found 18 molecular markers in common. In the region close to these markers are 15 genes: one transcription factor, four that have been reported in other studies of tolerance to water deficit, three related to root growth, and six that have been reported in the literature related to other types of stress. Keywords: Glycine max. Abiotic stress. GWAS. Germination. Vegetative stage. Plant breeding.
Soybean is the major oilseed crop grown worldwide and contributes to both human and animal nutrition. Due to its great importance, great efforts are made to develop new productive cultivars. However, though conditions, such as drought, have become more frequent with the climatic changes. These periods have caused great losses in crops, in soybean losses of 24 - 50% had recorded. Thus, many studies have focused on the critical phases of soybeans, however, the dry period can occur during any phase of the crop. Thus, for understanding this complex process and assist the development of tolerant cultivars, this study aims: (i) identify molecular markers and candidate genes associated with these markers in the process of tolerance to water deficit in soybean during the germination stage; (ii) identify molecular markers and candidate genes associated with these markers in the process of tolerance to water deficit in soybean during the vegetative stage. At each stage, it carried out two experiments in a randomized block design with 3 replications in a 100 x 2 factorial (Genotypes x Water availability). The cultivars, became from different companies, representing country's soybean diversity panel. The water availability was: the control condition (Field capacity) and the stress condition (-0.2 MPa (germination) and -1.2 MPa (vegetative stage)) with a duration of 20 days. The experimental plot at the germination stage was a row containing ten treated seeds and at the vegetative stage, it was a plant in a 3-liter pot of substrate. The substrate used in germination was sand, and in the vegetative stage, it was a mixture of soil and sand. For the germination stage, the stress period began at the time of planting the seeds, while the vegetative period was when the plants entered the vegetative stage 2 (V2). For each trait, genotypic values (gBLUP) were obtained using two approaches to the concept of tolerance. The first approach used the difference between the stress condition and the control to obtain the genotypic value. In the second approach, gBLUP values were obtained using data from stress and control conditions as treatments. The gBLUP values were then used in genome-wide association studies to obtain significant markers. At the germination stage, 25 SNP-type markers were significant using the first approach and 18 markers using the second. Among these, three markers were present in both approaches. In the region close to those three markers, are five genes: one related to the cell wall, two related to protein transport, and two transcription factors. At the vegetative stage, 114 markers were significant in the first approach and 68 in the second approach. In both approaches, it found 18 molecular markers in common. In the region close to these markers are 15 genes: one transcription factor, four that have been reported in other studies of tolerance to water deficit, three related to root growth, and six that have been reported in the literature related to other types of stress. Keywords: Glycine max. Abiotic stress. GWAS. Germination. Vegetative stage. Plant breeding.
Descrição
Palavras-chave
Glycine max, Soja - Melhoramento genético, Estresse hídrico, Germinação, Estudo de associação genômica ampla
Citação
FERREIRA, Dalton de Oliveira. Prospecção de genes candidatos ao deficit hídrico em soja . 2021. 103 f. Tese (Doutorado em Genética e Melhoramento) - Universidade Federal de Viçosa, Viçosa. 2021.