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6. DO ANY SPECIES BOUNDARIES....
Another five enzymatic loci (Mdh2, Per1, Adh1, Idh1 and Acoh1) mapped on LG4 and
covered around 40 cM (Figure 6.5D). The linkage between genes encoding aconitase hydratase
(Acoh1) and isocitrate dehydrogenase was observed in the HU5 x BO2 interspecific
family as well. Three enzymatic loci, Cap2, Mdhp2 and Hk1 spanned over the distance of
70 cM in the middle of LG2 (Figure 6.5B). The locus Est2 should be also placed within this
group for the reason that it was moderately linked with Mdhp2 in the population of L. multiflorum
VA7 x AS17. The remaining three enzymatic loci segregating in the BR3 x NZ15 were
allocated to three linkage groups; Gtdh2 to LG5, Per3 to LG6, and Skdh1 to LG7 (Figure
6.5E-G). The common feature of these enzymatic loci was linkage with katG markers and
proximity to transposons.
Bacteria Specific Amplification Polymorphism (B-SAP)
In total 33 markers revealed by primers complementary to different M. tuberculosis
sequences were mapped on the L. multiflorum x L. perenne genetic map that supported the
usefulness of such markers in genetic studies of plants. Moreover, the majority of them segregated
in the Mendelian fashion in the mapping population, BR3 x NZ15. Significant distortions
were observed for four markers, hence for 12% of loci and this value was significantly
below the overall level observed in this cross combination. Because these markers were
derived from bacteria, they were further referred to as Bacteria Specific Amplification Polymorphism
(B-SAP) with adding the name of a sequence or a gene from which primers were
derived if necessary. Thus markers revealed by primers complementary to KatG gene were
assigned as katG and those revealed by primers complementary to IS6110 as IS markers.
The majority of IS markers from six mapped were found on LG1. Two of them were
located on the proximal part while the other two were completely linked with OPA08-16
marker on the distal part of this group. Another marker, IS1 was linked with Tpo1 transposon
(TpMaca41a) on LG2, while IS8 was linked with AFLP marker, MctgEagc8 on LG5.
The katG markers were distributed among seven linkage groups. The most of them
were allocated on LG6 (eight) followed by LG4 and LG5 (five on each group). The most
striking result was the tight linkage between several katG markers on LG6 with locus Per3
encoding peroxidase. This result confirmed our previous predictions that at least some katG
markers can amplify peroxidase loci in plants. Similarly, another locus responsible for peroxidase,
Per1 located on LG4 was also linked with katG markers. Noteworthy, except of
peroxidases, katG markers tended to be linked with other enzymatic loci, especially encoding
dehydrogenases. For example, katG3-7 on LG2 was linked with Hk1 encoding hexokinase,
katG5-9 on LG4 was linked with Mdh2 encoding NAD-depended malate dehydrogenase, two
markers, katG8-6 and katG3-8 with Acoh1 responsible for aconitase hydratase and katG2-12
and katG2-14 with Gtdh encoding glutamate dehydrogenase. Moreover a linkage between
Est4 and katG5-11 was observed on LG1.
The katG markers segregated in the Mendelian fashion according to dominant mode
3:1. They were rarely distorted. However, all distorted katG markers were selected towards
the presence of a band.