Perennial teosinte-Gaspe hybrids: Inheritance of the number of leaves

We have analyzed inheritance of the number of leaves in hybrids between perennial teosinte (Euchlaena perennis = Zea perennis) and Gaspe (Zea mays), and we have also tested the relationship between the number of leaves, growing habits and evolutive cycle. Gaspe is extremely precocious and has a low leaf number, whereas perennial teosinte has a very long cycle and has a high number of leaves (see Table 1). In the F1, 88 plants, and in the F2 and F3, approximately 400 plants were studied. The number of leaves was taken from two stalks from plants selected at random, and the evolutive cycle was measured in days to tassel, days to silking and days to pollen.

Figure 1 shows that the frequency distribution of leaf number variation almost reached paternal extremes in the segregating generations. The average number of leaves found in F1, F2 and F3 did not differ significantly from the theoretical mean (10.9) of its progenitors. The calculated inheritance is 0.71, and the number of leaves would apparently be controlled by very few genes of additive effect. In the F2 and F3 populations, the number of leaves is significantly correlated with the evolutive cycle (Table 2). As to growing habits in populations F2 and F3, the annual plants have a significantly lower number of leaves than the bi-annuals (Table 3).

It can be deduced that the number of leaves associates as much with the evolutive cycle as with the growing habits. Perhaps the characteristics studied are conditioned by the same genes, or by different genes strongly linked in the same chromosomes. Nevertheless, we have found infrequently the recombination of characters in a segregating population, that is to say, precocious plants with high number of leaves and long cycle plants with low number of leaves. Therefore, it is probable that those characters are conditioned by linked genes more than by the same genes.

Table 1.

Figure 1.

Table 2.

Table 3.

Jorge Luis Magoja and Gabriela Nora Benito

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