Gene Cloning and Characterization - Genetics, Genomics and Breeding of Crop Plants - page 178

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Gene Cloning and
Characterization
Renate Horn* and Sonia Hamrit
ABSTRACT
In sunflower, two approaches have been followed to isolate genes:
map-based-cloning and candidate gene approaches. Map-based
cloning of nuclear male sterility and fertility restoration genes, as well
as, genes conferring resistance to downy mildew so far has been
unsuccessful. This is primarily due to the large genome size, the high
content of repetitive elements, the lack of publicly available large
mapping populations and large insert genomic libraries. On the other
hand, candidate gene approaches in the areas of developmental
biology (e.g., embryogenesis, non-dormancy, pollen and pistil-specific
genes), abiotic stress (e.g., heat-shock and drought-related genes),
disease resistance and quality traits (e.g., fatty acid biosynthesis or
tocopherol biosynthesis) have proven to be very successful. However,
in sunflower even if a gene was identified, the lack of a good
transformation system hampers verification of the candidate gene.
Fortunately, heterologous systems and mutant analyses have proven
to be helpful for gene verification and characterization. In spite of
these problems, enormous progress has been made on the cloning of
genes in sunflower. The current expansion of genomic resources in
sunflower promises to accelerate the process of isolation and
characterization of agronomically important genes.
Keywords: map-based cloning; molecular marker; BAC libraries;
candidate gene approach; mutants
Institute of Biological Sciences, Department of Plant Genetics, University of Rostock,
Albert-Einstein-Str. 3, 18051 Rostock, Germany.