Genetics of environmental resistance and super-genes: Latente heat tolerance

In the preceding article, the authors presented data on linkages of latente with aluminum tolerance. The data fit the hypothesis of two pairs of complementary dominant genes, linked to R and B, responsible for aluminum tolerance. Now we will try to fit heat tolerance data to the hypothesis. In MNL 56:28-30 in Table 1 there are such data. Considering live plants as Lte and dead as lte Table 1 can be built. For the Cateto line C1 there was a perfect fit both for Lte and R to a 9:7. The interaction was highly significant, X2=16.78** with P<0.01 indicating strong linkage. For C2 the results were much worse, with significant deviations from the expectations tested and non-significant interaction. The more quantitative effects of the classification for R and r were much worse, and C2 was dropped out from further analysis. The seedlings were transplanted to a field nursery in two separate groups, R and r, and at flowering time classified for the factors g and sr2. A reading of B was not done. These readings are presented in Table 2. Since in the work with aluminum sr2 had a very high mortality of its own, it was eliminated from further analysis.

In Table 3, the values of p with their standard errors are presented for the segregations indicated. For the segregations involving seeds and seedlings, n was taken as the geometric mean of n for seeds and n for seedlings. Both maximum likelihood and the product moment method were used. For Lte linkage, due to high differential mortality in b and c cells, the use of the first method had no real solution. Turning to the results of the second method, it is clear that Lte2 must be between g and R. As indicated in the preceding article, we transformed their values to cM and by differences between these values adjusted to the known distance between g and R, giving the results g Lte 8 units and Lte R 6 units. So the most probable position of Lte2 is 55 in chromosome ten.

Since it seems that heat tolerance and aluminum tolerance are pleiotropic effects of the same effective factor, the data from both experiments were pooled in one Joint analysis. The results are shown in Table 4. With an Lte R distance of 5 units, and between g and R, Lte2 must be around position 56 in chromosome ten.

Table 1.

Table 2.

Table 3.

Table 4.

L. T. de Miranda, L. E. C. de Miranda and E. Sawazaki

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

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