A mutation of a gene (discovered in Festuca pratensis
Huds.
and designated sid ) confers indefinite greenness on
senescing leaves. Via intergeneric hybrids with Lolium multiflorum
L. and Lolium perenne L., the mutant gene
(sidy)
has been introgressed into a range of Lolium backgrounds. Using
genomic in situ hybridization we have identified
segments carrying sidy
in recombinant chromosomes of Lolium–Festuca introgression
lines. We also used L.
perenne lines segregating 1[ratio ]1 for the staygreen
character to tag the gene with molecular markers. In two mapping
populations a total of 84 genotypes were screened with isoenzymes, RAPD
primers,
RFLP probes and AFLP
primer pairs. Over 180 polymorphic loci were identified, representing 10
linkage groups spanning 600 cM. Two
AFLP markers are linked to sid at 4·6 and 14·9 cM,
close enough to be usable for marker-assisted selection.
Introgression of sidy
into Lolium temulentum L. resulted in the production of
near-isogenic inbreeding lines
suitable for comparative studies of gene expression. Using a variation
of the
method of representational difference
analysis a very small number of cDNAs have been identified as promising
candidates for sid, or genes directly
regulated by sid.