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6. DO ANY SPECIES BOUNDARIES....
Noteworthy, all enzymatic loci but Sod1, deviating from the Mendelian model of inheritance in
the interspecific population BR3 x NZ15, were tightly linked with transposon sequences.
6.3.4. Inheritance of selected traits in intra- and interspecific crosses
Seedling root fluorescence (SRF)
Seedling root fluorescence (SRF) segregated in both interspecific F 2
populations (BR3
x NZ15 and HU5 x BO2) and in the F 2
population of L. multiflorum, VA7 x AS17. Unsurprisingly,
no segregation was observed in the L. perenne F 2
population, KY20 x BB6, which was
derived from nonfluorescent parents (Table 6.11). The roots of the F 1
hybrid did not fluoresce
as well.
Segregation of seedling root fluorescence was consisted with the monogenic dominant
mode of inheritance in the L. multiflorum population and in the F 2
derived from the interspecific
cross between L. perenne and L. multiflorum, HU5 x BO2. However, the significant
deviation from the expected 3:1 ratio was observed in the second interspecific population
derived from the cross between L. multiflorum and L. perenne, BR3 x NZ15. By contrary, the
segregation of seedling root fluorescence in this population was in agreement with the 9:7
ratio typical of two complementary genes.
A report from genetic mapping studies in the L. multiflorum x L. perenne population,
BR3 x NZ15 provided other evidences that at least two genes may be responsible for the
SRF character. Two regions were identified on the first linkage group (Figure 6.5A). The
first locus was located on the proximal part of LG1 and it was tightly linked with Lolcopia2
marker Lc2Pat22 (1.3 cM). It was also located more than 30 cM away from Est4 locus. This
locus was further assigned as SRF1 with respective alleles, SRF1 as dominant and srf1 as
recessive. The second one, further described as SRF2 with dominant SRF2 and recessive
srf2 alleles, mapped on the same linkage group but in the distal part, in about 3.4 cM away
from of a small cluster of three AFLP markers, McacEaac32, McaaEact15 and MctgEaac22.
In proximity to this region, the insertion site of Tpo1 transposon (TpPat41) was found and
enzymatic locus, Pgdh1 encoding phosphogluconate dehydrogenase (within 9 cM). Appar-