RESEARCH REPORTS TGC REPORT 52, 2002
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A new allele at the potato leaf locus derived from L. chilense accession LA 1932
is discovered in a geminivirus resistance project.
Scott, J.W.
University of Florida, IFAS, Gulf Coast Research & Education Center, Bradenton, FL
34203
The potato leaf (c) locus has been mapped to chromosome 6 near the sp and B loci
Tanksley et al., 1992; Weide et al., 1993). In 1990 we discovered resistance to the
geminivirus, tomato mottle virus (ToMoV), in several accessions of L. chilense (Scott
and Schuster, 1991). Resistance was introgressed into tomato by crossing entirely with
cut leaf recurrent parents. Nevertheless, we began to find potato leaf segregants in
determinate plants derived from LA 1932 (and LA1961). The potato leaf trait seemed to
be associated with ToMoV resistance and potato leaf was used along with sp to anchor
RAPD markers linked to resistance loci (Griffiths, 1998; Griffiths and Scott, 2001). In
that research it was observed that the potato leaf type observed was not as easily
identified as with c genotypes.
To determine if the LA 1932
derived potato leaf was in fact
an allele at the c locus, an
inbred with the trait, 745-Y1,
was
crossed
with
c leaf
accessions LA 2510 and LA
2513 and Fla. 7781 (c+).
Subsequently, F2 seed was
obtained
for
each
cross.
Parents, F1 and F2 generations
were grown in Todd planter flats
in a greenhouse in spring,
2002. Plants were rated as wild
type (cut leaf), potato leaf (c), or
LA 1932 potato leaf (Fig. 1)
when seedlings were at the 2-3
leaf stage. The LA 1932 derived
potato leaf is not as distinctive
as c, the leaf generally has a
lower length to width ratio, is
more rounded than pointed, and
has a small serration in the leaf
margin (Fig. 1). As can be seen
in Fig. 1d, the axillary leaflets
often connect to the terminal
leaflet unlike c where they are
generally separate. The LA 1932
31
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