ISSN:
1573-4927
Keywords:
maize
;
starch synthesis
;
endosperm
;
leaves
;
amylose-extender
;
branching enzyme
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Soluble starch synthases (SS) and branching enzymes (BE) from 20-day-old maize leaves and 22-day-old seeds of normal andamylose-extender (ae) were purified by DEAE-cellulose chromatography. Elution profiles of leaf extracts showed one major SS and two BE fractions from both genotypes. The SS fractions from normal andae leaf extracts were capable of citrate-stimulated starch synthesis and had different reaction rates with various primers. The two BE fractions from normal leaf extracts differed significantly from each other but not when compared to the same BE fromae. Comparison of BE fractions fromae and normal leaves showed no differences based on chromatographic, kinetic, and immunological properties. Comparison of the leaf enzymes with endosperm enzymes showed major differences. Leaf extracts did not contain SSII or BEIIb observed in endosperm extracts. Developingae endosperm lacks BEIIb activity andae is the structural gene for BEIIb. The tissue specific expression of BEIIb in the endosperm provides the basis for explaining the tissue-specific expression ofae. We propose that as BEIIb is expressed in the endosperm, but not leaves, allelic substitution at theae locus modifies only endosperm starch synthesis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00553629
Permalink