Identificação de QTLs em milho associados à qualidade de sementes no pós-processamento

Abstract

Sustainability of high yield levels on maize depends, among several factors, on the availability of high quality seeds. Resistance to processing damage is a critical factor on maize seed quality since damage during processing contributes on the quality loss during storage. The objective of this study was to identify QTLs in maize associated to seed resistance to processing damage. A 231 F2:3 segregating population derived from a cross between a resistant and a susceptible inbred to damage was screened to seed vigor after processing simulation. Levels of reduction on vigor were applied on a QTL mapping based on a 52 SSR molecular map. One QTL was identified on chromosome 9 as associated to processing damage resistance, under a LOD score of 6.56 and explaining 14% of the phenotypical variance. The genomic region identified is known as associated to physical seed traits and as containing genes related to germination process. Evidence of epistatic effects indicates that this trait involves multiple genes acting in a complex way. Similarly, the possibility of a major gene (also considering the accepted model of complete dominance) acting in recessiveness for resistance does not discard the possibility of minor genes with different effects in the degree of susceptibility. A further analyses based on differential expression may contribute on the clarification of factors involved on maize seed quality after processing.