engleski

Pleiotropy: measurement and relevance in plant breeding

Trait correlations are common phenomena in plant breeding. Genetically, pleiotropy refers to the phenomenon of genetic trait correlations when some common genes underlie the phenotypic variation in multiple traits. This is particularly common in complex (polygenic), agronomically and biologically relevant traits. We employed multitrait composite interval mapping to determine number, effect and degree of pleiotropy in quantitative trait loci (QTL) affecting several complex components of photosynthesis such as light absorption, trapping of excitation energy, dissipation of excess light, electron transport, and overall photosynthetic performance in maize by analyzing parameters of chlorophyll a fluorescence. Our results demonstrated that QTL analysis for light absorption, trapping of excitation energy, dissipation of excess light, and overall photosynthetic performance detected one significant pleiotropic locus on chromosome 7, coinciding with the gene gst23 that might be associated with efficient photosynthesis under different field scenarios. We argue that some subtle QTL effects which lied below thresholds for statistical detection might be biologically important. However, further genetic and genomic analyses may eventually discriminate and prove whether genetic trait correlations were due to “true” pleiotropy or linkage.

complex traits, photosynthesis, pleiotropy, quantitative genetics

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