Revealing the genetic architecture of soybean resistance to the stink bug complex

• Ano de defesa: 2021
• Autor(a) principal: Martins, Emanoel Sanches
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Glycine max; GWAS; Mapeamento de QTLs; QTL mapping; QTL validation; Resistance to insects; Resistência a insetos; Validação de QTLs
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11137/tde-11112021-112335/

Damage caused by the stink bug complex in soybean has exceeded the figure of millions of dollars annually. Cultivating extensive areas, the damage due to these insects has increased, reducing the gains in production. Among the insects control, resistant cultivars to the stink bug complex may be an alternative to the use of insecticides. It is known that this resistance has a quantitative nature and is thus controlled by several genes. In this way, strategies that aim to clarify the control of these insects become overpowering for the future of soybeans. To this end, the objective of this project was to identify and elucidate the genetic architecture of soybean resistance to the stink bug complex. In the first study, we seek to map regions of resistance and elucidate the interactions between QTLs and environments involved in resistance to the stink bug complex on soybean, in a population of recombinant inbred lines (RILs). For this purpose, a population of 256 RILs were used, developed from the cross between IAC-100 (resistant) and CD-215 (susceptible). The experiments were carried out at the ESALQ experimental area in the city of Piracicaba, SP, during the seasons 2012/2013, 2013/2014, 2014/2015, 2015/2016, 2016/2017, 2017/2018, and 2018/2019. We use an alpha-lattice 10 x 26, with three replications as the experimental design. Nine traits associated with resistance to the stink bug complex and agronomic performance were evaluated. For genotyping of RILs, the genotyping technique by sequencing (Genotyping-by- Sequencing) was used. Subsequently, with the data obtained and the analyzes carried out, we found a total of seven significant QTLs, 5 of which were considered as stable QTLs and with potential for use in marker assisted selection. Additionally, in this first study, we developed an epistasis study using the SPAEML software, in which we conclude that the size of the studied population (n = 256) is too small to quantify epistatic effects. In the second study, we developed a work aimed to validate the regions found by the QTL mapping through a genomic wide association study. A soybean breeding panel composed of 299 lines, obtained from a multiparental crossing, was evaluated. This population was evaluated during the years 2018/2019 and 2019/2020, in the experimental area of ESALQ in a 16x19 alpha-lattice design with three replications. We evaluated traits that had significant QTLs in the QTL mapping. Genotypic data were obtained by genotyping by sequencing. With the data obtained, we calculated the means adjusted through mixed models and subsequently performed the GWAS to validate the regions of resistance to the stinkbug complex. A total of 22 QTNs were found, with three regions validating the QTLs found in the previous mapping. For our studies, chromosomes 1, 6, and 15 appear as regions with possible candidate resistance genes and with great potential to assist breeding programs to decide for resistant cultivars.