F1 embryo proteins as valuable tools in better understanding of heterosis
--Konstantinov, K; Coric, T; Drinic, G and Drinic, SM

The creation of new and more productive maize hybrids has as a prerequisite inbred lines possessing both general and specific combining ability, determined almost entirely through studies at the phenotypic morphological level. In a companion paper are reported results on the presence of more hybrid-embryo specific proteins in higher as compared to lower yielding crosses.

This study is focused on parental lines participating in genome expression in the F1 maize embryo at the level of total and salt soluble proteins. Total and salt soluble proteins were analyzed in embryo tissue of seven single cross hybrids produced by crossing one inbred used as the female parent and seven inbreds used as the male parents. In this way it was expected to distinguish the specific contribution of each inbred line genome in genetic control of protein synthesis.

A high resolution polyacrylamide gel electrophoresis (PAGE) system (Wang et al., Seed Sci. Technol. 22:51-57, 1994) was used for protein separation according to molecular weight. Electrophoregrams of total F1 embryo proteins are presented in Figure 1 and salt soluble proteins in Figure 2.

Both quantitative and qualitative differences between analyzed crosses are obvious. Protein fractions which are candidates as markers associated with heterotic effect are indicated by arrows.

Parallel studies of embryo specific proteins and polyA-mRNAs of parental lines and hybrid combinations during kernel development after pollination are in progress. Specific fraction/fractions of protein/proteins synthesized only in particular hybrid combinations could be used as a tool for identification and characterization of the encoded gene/genes important in manifestation of heterotic vigor.

Figure 1. Electrophoregram of total proteins isolated from the maize dry embryo of different crosses: line 1 (ZPL153 x ZPL218); line 2 (ZPL153 x ZPL2/2); line 3 (ZPL153 x ZPL2/2); line 4 (ZPL153 x ZPL17); line 5 (ZPL153 x ZPL59G); line 6 (ZPL153 x ZPL655); line7 (ZPL153 x ZPL573).

Figure 2. Electrophoregram of salt soluble proteins isolated from the maize dry embryo of different crosses. Legend is the same as in Figure 1.


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