Mutations in starch BRANCHING ENZYME 2a suppress the traits caused by the loss of ISOAMYLASE1 in barley
Key message The hvbe2a mutations restore the starch-deficient phenotype caused by the hvisa1 and hvflo6 mutations in barley endosperm. The genetic interactions among starch biosynthesis genes can be exploited to alter starch properties, but they remain poorly understood due to the various combinatio...
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Veröffentlicht in: | Theoretical and applied genetics 2024-09, Vol.137 (9), p.212, Article 212 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Key message
The
hvbe2a
mutations restore the starch-deficient phenotype caused by the
hvisa1
and
hvflo6
mutations in barley endosperm.
The genetic interactions among starch biosynthesis genes can be exploited to alter starch properties, but they remain poorly understood due to the various combinations of mutations to be tested. Here, we isolated two novel barley mutants defective in starch
BRANCHING ENZYME 2a
(
hvbe2a-1
and
hvbe2a-2
) based on the starch granule (SG) morphology. Both
hvbe2a
mutants showed elongated SGs in the endosperm and increased resistant starch content.
hvbe2a-1
had a base change in
HvBE2a
gene, substituting the amino acid essential for its enzyme activity, while
hvbe2a-2
is completely missing
HvBE2a
due to a chromosomal deletion. Further genetic crosses with barley
isoamylase1
mutants (
hvisa1)
revealed that both
hvbe2a
mutations could suppress defects in endosperm caused by
hvisa1
, such as reduction in starch, increase in phytoglycogen, and changes in the glucan chain length distribution. Remarkably,
hvbe2a
mutations also transformed the endosperm SG morphology from the compound SG caused by
hvisa1
to bimodal simple SGs, resembling that of wild-type barley. The suppressive impact was in competition with
floury endosperm 6
mutation (
hvflo6
), which could enhance the phenotype of
hvisa1
in the endosperm. In contrast, the compound SG formation induced by the
hvflo6 hvisa1
mutation in pollen was not suppressed by
hvbe2a
mutations. Our findings provide new insights into genetic interactions in the starch biosynthetic pathway, demonstrating how specific genetic alterations can influence starch properties and SG morphology, with potential applications in cereal breeding for desired starch properties. |
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ISSN: | 0040-5752 1432-2242 1432-2242 |
DOI: | 10.1007/s00122-024-04725-7 |