MINAS GERAIS, BRAZIL
EMBRAPA Maize and Sorghum
Mapping a novel opaque endosperm mutant
using SSR markers
--Maki, CS, Carneiro, NP, Guimarães,
CT, Lopes, MA, Paiva, E
To understand more about the relation among
the opaque mutations, zein levels, endosperm hardness and nutritional quality
of the maize endosperm we started to characterize native maize opaque endosperm
mutants. The opaque mutants described in the literature have in general
higher nutritional quality and lower zein levels compared to the wild type
genotypes. These novel maize opaque endosperm mutants have soft endosperm,
low nutritional quality and zein levels similar to the wild type endosperm
(Guimarães et al., Rev. Bras. Genet. 18, 2, 259-264). One
of the mutant genotypes (BOL II) was crossed to the wild type genotype
(BR-201) and the F2 plants were self-pollinated to F4. DNA pools from homozygous
vitreous and opaque plants were analyzed in bulked segregant analysis (Michelmore
et al., PNAS 88:9829-9832) to map the locus related to endosperm hardness
in this mutant. Four out of 276 primer pairs tested (Research Genetics)
showed to be polymorphic when bulks of DNA from individuals of vitreous
and opaque endosperm were compared: MAG.T01.D04, bngl125, bngl382
and phi083, located at 2.01-2.02, 2.02, 2.03 and 2.04 respectively.
To get more accurate map position, DNA from these individuals was tested
separately (Figure 1). We are in the process of refining the data using
RFLP markers surrounding this genomic region. The same F4 population will
be used in a subtractive hybridization strategy to isolate genes involved
in the definition of the soft endosperm trait.
Figure
1. SSR marker analysis showing polymorphism among F4 individuals homozygous
for vitreous (Group A) and opaque (Group B) endosperm. Parent A is the
novel mutant and Parent B is the wild type.
Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.
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