Transcriptome and proteome wide identification of genes that are related to heterosis manifestion in maize seedling roots

• Applicant: Professor Dr. Frank Hochholdinger
• Subject Area: Plant Breeding and Plant Pathology
• Term: from 2003 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5410304

Heterosis describes the superior performance of hybrids compared to the average of their parental inbred lines and is attributed to the interaction of a considerable number of genetic loci. A major step towards the understanding of heterosis will be the molecular identification and characterization of these loci. We suggest therefore a transcriptome- and proteome wide characterization of heterosis related gene expression and protein accumulation in roots of young seedlings of maize. The analyses will comprise six combinations of four different inbred lines including one flint/flint (A x B) and one dent/dent (C x D) intra-group cross and the four possible flint/dent inter-group crosses of these inbred lines (A x C, A x D, B x C and B x D). This will allow to study four alleles of each gene in three different hybrid combinations. Inclusion of reciprocal crosses in our experiments will allow to study parent of origin effects. In the initial phase of the project, early root development of selected inbred lines and hybrids will be quantitatively analyzed on the phenotypical and on the histological level. Microarray experiments will then be conducted with young seedling roots of all six reciprocal crosses at one defined developmental stage. The same developmental stage of three of these reciprocal hybrids will also be subjected to a proteomic analysis. Our objective is to identify a subset of genes/proteins which is differentially expressed in inbred lines versus hybrids and to test which of these genes are expressed according to the genetic models of the dominance or overdominance hypothesis. Among the differentially expressed genes we hope to identify genes whose relative expression level can be correlated with the degree of heterosis of a given hybrid. Organization of profiling data in databases and integration of the molecular data into a modeling framework might help to predict suitable inbred combinations for future hybrid production. In summary with this approach we hope to contribute to the molecular understanding of the complex genetic networks involved in heterosis.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1149: Heterosis in Plants