CAMPINAS, SAO PAULO, BRAZIL
Instituto Agronomico
Resistance to Angoumois moth and corn weevil in husked ears
--Luiz Eugenio Coelho de Miranda, Luiz Torres de Miranda and Sylmar
Denucci
In MNL 54:15-19 we reported on inheritance and linkages of multiple aleurone
layering. Using ACRE 134, and AMAZONAS unnumbered collection, and Entrelacado
from the same source, and a waxy source, versions with Mal, wx
on our opaque-2 versions of IAC Maya and IAC 1 were obtained. The pedigrees
simplified are Mal wx x IAC Maya o2(4) -o2 Mal wx
and Mal wx x IAC 1 o2(4) -o2 Mal wx, Mal being
"multiple aleurone layering". After the original cross and 3 backcrosses
pure versions of o2 Mal wx were obtained. The original Mal
collections are from a super humid very hot climate with no distinct dry
season limiting for maize growing and optimum to insects. They are very
badly adapted to our region down to pollen semi-sterility. In the beginning
of June 5 ears of each entry of the acclimated material were husked and
put in pairs touching in split plots, with their opaque-2 only versions
on a shelf board, each pair about 30cm from the other in an ambient room
condition. At the beginning of November the unholed and holed kernels were
counted. The attack was by both Sitophilus oryzae or S. zeamais
(Motschulsky), which are prevalent in our area, and Sitotroga cerealella
(Oliver), not discriminating damage of one pest from the other. The data
and analysis are presented in Table 1. For the IAC Maya the total effect
of Mal over mal was +1.6±1.2, non-significant, but
in the IAC 1 with +9.0±1.5, significant at P<0.01. In the 3 ears
of each, which were better than the original opaque-2 versions, 11 grains
each of both holed and unholed kernels were characterized in the number
of aleurone layers by a third party. The results are presented in Table
2. Under binocular aleurone layer classification, a few kernels changed
class, and that is why there are not equal numbers in unholed and holed
classes.
Table
1. Number of unholed (U), and holed (H) grains in the pairs studied
with the calculated relevant parameters.
Although we planted what we thought were pure Mal by analysis
of 11 kernels per ear of selfed mothers, checking two or more layers, the
readings gave initially 4 classes: 1) clearly only 1 layer, 2) with tendency
to have more than 1 layer, 3) clearly 2 layers and 4) with more than 2
layers. By a contingency test in the 2x4 factorial it was seen that best
results were gotten by pooling 1) with 2) and 3) with 4) (Table 2). Curiously
for IAC Maya, which gave a lesser effect, now we have greater significant
effects and vice versa for the IAC 1. It seems clear that now selecting
within a population with variability, for the stabilization and enhancement
of multialeurone expression, a much greater effect will probably be achieved
since now we have a mean unholed % of 68.3±6.2 for 2 or more layers
as opposed to the first total of 1, 3, 5, 6, 9, 10 of 23.8±1.0 in
whole segregating ears, a difference of 44.5±6.3. Parallel populations
with the factors were field tested for grain yield in 4 localities with
4 reps per place and in the fourth backcross, now to the normal endosperm,
yielded in IAC Maya 87% and in IAC 1 119% in relation to their counterparts.
Table
2. Determination in the ear families 1, 3, 5, 6, 9, and 10 with Mal
from Table 1 of the number of layers in the unholed (U), and holed (H)
classes with the calculated relevant parameters. As seen, the families
were not pure for multiple aleurone layering, perhaps because of environmental
interaction effects.
Please Note: Notes submitted to the Maize Genetics Cooperation
Newsletter may be cited only with consent of the authors
Return to the MNL 63 On-Line Index
Return to the Maize Newsletter Index
Return to the MaizeGDB Homepage
