Genetic distance studies in maize and its wild relatives based on biochemical assays

Electrophoretic patterns produced by PAGE of soluble germ proteins and isoenzyme patterns of esterase in soaked germs of races of maize, species of teosinte, species of Coix, Trilobachne and Chionachne were used to calculate similarity indices (S.I.) in all possible combinations. Pooling the similarity indices of isoenzyme esterase and soluble germ proteins gave cumulative similarity indices (C.S.I.). The average similarity indices (A.S.I.) were worked out from C.S.I.'s of races, species and genera. This was found to give a concise picture of interspecific and intergeneric electrophoretic affinities. A.S.I.'s indicated the following similarity hierarchy:

Maize :Teosinte > Coix > Trilobachne > Chionachne

Teosinte :Maize > Coix > Trilobachne > Chionachne

Coix :Maize = Trilobachne > Teosinte = Chionachne

Trilobachne :Coix > Maize > Chionachne > Teosinte

Chionachne :Trilobachne > maize > Coix > Teosinte

The comparison of A.S.I.'s revealed that Chionachne showed the least similarity with other genera, followed by Trilobachne and Coix. The similarity pattern of maize and teosinte was quite alike.

Values of genetic distances obtained were represented as polygon graphs. A comparative study of these graphs revealed that maize and teosinte were more or less equidistant from other genera. While the distance between maize and teosinte was less than 50 units, other genera were separated from them by at least 65 units. Maize was nearer to teosinte, followed by Coix, Trilobachne and Chionachne. A similar situation was observed with teosinte also. Coix polygon indicated equidistant placement of maize and teosinte, while Chionachne was the farthest and Trilobachne fell in between. Trilobachne exhibited nearly equidistant placement to Chionachne and teosinte along one diagonal, maize and Coix on the other. The squarish polygon of Chionachne indicated near equidistance of this genera with other genera of Maydeae.

Figure.

V. V. Shenoy, K. N. Srivastava, J. K. S. Sachan and K. R. Sarkar

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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