GWAS for resistance to mediterranean corn borer and agronomic traits in a MAGIC population of maize

Resumen del póster presentado en el Congreso celebrado en Saint-Malo, Francia, entre el 22 y el 25 de marzo de 2018.
Understanding of the genetic basis of quantitative traits such as resistance to pest and yield are necessary to optimize the breeding programs to simultaneously improve both characters. Genome Wide Association Studies (GWAS) are useful tools to achieve this goal, especially when the mapping population is a Multi-Parent Advanced Generation Intercross (MAGIC) population. A MAGIC population of 672 recombinant inbred lines (RIL) was generated after inter-mating for six generations a synthetic variety composed of eight genetically diverse founder lines. This MAGIC population have been genotyped by genotyping based on the sequence (GBS) and evaluated for resistance to attack by the Mediterranean Corn Borer (MCB, Sesamia nonagrioides) and for yield, plant height and silking. We found seven QTL and six candidate genes for grain resistance, forty-eight QTL and sixty candidate genes for plant height, thirty-four QTL and forty-nine candidate genes for silking time, five QTL and nine genes for tunnel length, and finally fifteen QTL and twenty-four candidate genes for grain yield. We expect that tunnel length produced by MCB larvae attack and plant height also increase when yield is improved due to the genetic correlation between these traits. The intermediate role of plant height on the undesirable genetic relationship between yield and resistance was highlighted suggesting that tradeoff between plant growth and resistance could mediate that undesirable relationship. MAGIC population was useful to discover genomic regions involved in MCB resistance with greater precision than those determined using more structured populations,. The GRMZM2G178190 (Zm00001d048129) gene related to the natural resistance could intervene in the ear resistance and the GRMZM2G057140 (Zm00001d043286) gene that is related to the regeneration of the cell wall could be related to stem resistance to corn borer attacks. A genetic improvement program can be designed with the 5 QTL detected for tunnel length using markers-assisted selection to decrease the tunnel length without neglecting QTL for grain yield, thus improving both traits.
Plan Nacional I+D. Spain, Feder EU