Resistência ao tripes-do-prateamento e seleção em genótipos interespecíficos de amendoim
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Data
2016-05-25
Autores
Pirotta, Melina Zacarelli [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O amendoim (Arachis hypogaea L.) é uma cultura oleaginosa de grande importância para o agronegócio brasileiro. Um dos principais fatores que afetam sua produção é a incidência de pragas, com destaque para o tripes-do-prateamento, Enneothrips flavens, Moulton, 1941 (Thysanoptera: Thripidae). Têm-se sugerido que genes que condicionam a resistência genética a esta praga, podem ser encontrados em outras espécies do gênero Arachis L. Entretanto, a utilização de espécies silvestres no melhoramento, torna-se dificultada por barreiras de esterilidade, sendo a maioria devido às diferenças de constituição do genoma e de ploidia. Para contornar essa incompatibilidade, sugeriu-se a obtenção de anfidiploides, resultantes do cruzamento de espécies diploides, seguido da duplicação de seus cromossomos, para então cruzá-los com o amendoim cultivado. Mediante o exposto, este trabalho teve como objetivos estudar o potencial de resistência ao tripes-do-prateamento em populações segregantes iniciais do cruzamento envolvendo a cultivar comercial IAC 503 e o anfidiploide sintético (A. magna x A. cardenasii)4x, monitorar os caracteres indicadores de proximidade agronômica dos segregantes interespecíficos com genótipos da espécie cultivada, bem como a seleção de genótipos superiores por meio de análises uni e multivariadas. Os experimentos foram conduzidos no esquema de blocos aumentados de Federer com testemunhas intercalares em duas gerações: F3, conduzida no ano agrícola de 2013/14 e F4, conduzida em 2014/15, sob infestação natural do inseto. A resistência ao tripes foi avaliada por meio de sua infestação e pelos sintomas de injúrias causadas pelo inseto. Foram avaliados também, alguns componentes de produção como indicadores da proximidade dos genótipos segregantes ao cultivado. Para estes caracteres, foram utilizadas as estimativas dos componentes genéticos, ganho genético e predição dos valores genéticos, calculados via modelos mistos (REML/BLUP). Para as análises multivariadas foram utilizadas as técnicas de componentes principais, análise de agrupamento hierárquico e não hierárquico com os dados das progênies de geração F4. Os resultados deste trabalho demonstram que as análises univariada e multivariada foram eficientes na seleção das melhores progênies, evidenciando a superioridade agronômica das mesmas, quanto aos componentes de produção e de resistência ao tripes. Porém, apesar de algumas progênies segregantes selecionadas como resistentes apresentarem bons componentes de produção, seu grau de adequação agronômica aos genótipos A. hypogaea L. ainda é pequeno. Assim, a identificação de progênies com resistência ao tripes geneticamente próximas às espécies do gênero Arachis L., constitui interessante fonte para estratégias futuras de introgressão gênica, podendo para isso, ser utilizado o método dos retrocruzamentos para inserção dos genes desejáveis de resistência e consequente recuperação dos genótipos adaptados, obtendo-se ao final do processo seletivo, cultivares comerciais portadoras de resistência ao tripes e com caracteres agronômicos e comerciais superiores.
The peanut (Arachis hypogaea L.) is an oilseed crop of great importance for Brazilian agribusiness. One of the main factors affecting its production is pests incidence, mainly thrips, Enneothrips flavens, Moulton, 1941 (Thysanoptera: Thripidae). There have suggested that genetic resistance to this pest can be found in other species of the genus Arachis L. However, the use of wild species in breeding was hampered by sterility barriers, mostly due to differences in the genome constitution and ploidy. To work around this incompatibility, it was suggested obtaining amphidiploid, resulting from the crossing of diploid species, followed by duplication its chromosomes, and then cross them with cultivated peanut. Through the above, this study aimed to study the potential for resistance to thrips in early segregating populations crossing involving commercial cultivar IAC 503 and synthetic amphidiploid (A. magna x A. cardenasii) 4x, monitor the agronomic traits proximity indicators of interspecific segregating with cultivated species, as well as the selection of superior genotypes using univariate and multivariate analyses. The experiments were conducted on the Federer augmented blocks with additional checks in two generations: F3, conducted in the agricultural year of 2013/14 and F4, conducted in 2014/15, under natural insect infestation. The thrips resistance was evaluated by its infestation, and the symptoms of injuries caused by insects. It was also evaluated, some production components such as proximity indicators of segregating the genotypes grown. To do so, estimates were used genetic components, genetic gain and prediction of breeding values calculated by mixed models (REML/BLUP). For multivariate analyses were used progenies in F4 generation, through technique principal components and cluster analysis. The results show that the univariate and multivariate analyses were effective in selection the best progenies, demonstrating the agronomic superiority of the same, as the components of production and resistance to thrips. However, despite some segregating progenies selected as resistance present good production components, the degree of agronomic suitability to the genotype A. hypogaea L. is still small. Thus, the identification of progenies with genetic resistance to thrips next to genus Arachis L. is an interesting source for future strategies of gene introgression, using the backcrossing method for insertion desirable genes of resistance and posteriorly recovery of adapted genotypes, getting to the end of the selective process, commercial cultivars with thrips resistance and good agronomic traits.
The peanut (Arachis hypogaea L.) is an oilseed crop of great importance for Brazilian agribusiness. One of the main factors affecting its production is pests incidence, mainly thrips, Enneothrips flavens, Moulton, 1941 (Thysanoptera: Thripidae). There have suggested that genetic resistance to this pest can be found in other species of the genus Arachis L. However, the use of wild species in breeding was hampered by sterility barriers, mostly due to differences in the genome constitution and ploidy. To work around this incompatibility, it was suggested obtaining amphidiploid, resulting from the crossing of diploid species, followed by duplication its chromosomes, and then cross them with cultivated peanut. Through the above, this study aimed to study the potential for resistance to thrips in early segregating populations crossing involving commercial cultivar IAC 503 and synthetic amphidiploid (A. magna x A. cardenasii) 4x, monitor the agronomic traits proximity indicators of interspecific segregating with cultivated species, as well as the selection of superior genotypes using univariate and multivariate analyses. The experiments were conducted on the Federer augmented blocks with additional checks in two generations: F3, conducted in the agricultural year of 2013/14 and F4, conducted in 2014/15, under natural insect infestation. The thrips resistance was evaluated by its infestation, and the symptoms of injuries caused by insects. It was also evaluated, some production components such as proximity indicators of segregating the genotypes grown. To do so, estimates were used genetic components, genetic gain and prediction of breeding values calculated by mixed models (REML/BLUP). For multivariate analyses were used progenies in F4 generation, through technique principal components and cluster analysis. The results show that the univariate and multivariate analyses were effective in selection the best progenies, demonstrating the agronomic superiority of the same, as the components of production and resistance to thrips. However, despite some segregating progenies selected as resistance present good production components, the degree of agronomic suitability to the genotype A. hypogaea L. is still small. Thus, the identification of progenies with genetic resistance to thrips next to genus Arachis L. is an interesting source for future strategies of gene introgression, using the backcrossing method for insertion desirable genes of resistance and posteriorly recovery of adapted genotypes, getting to the end of the selective process, commercial cultivars with thrips resistance and good agronomic traits.
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Palavras-chave
Análise de agrupamento, Arachis hypogaea L., Componentes principais, Enneothrips flavens, REML/BLUP, Cluster analysis, Principal components