POTENTIAL OF TRISPECIES BRIDGE CROSSES AND RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS FOR INTROGRESSION OF MEDICAGO-DAGHESTANICA AND M-PIRONAE GERMPLASM INTO ALFALFA (M-SATIVA)
Tj. Mccoy et Cs. Echt, POTENTIAL OF TRISPECIES BRIDGE CROSSES AND RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS FOR INTROGRESSION OF MEDICAGO-DAGHESTANICA AND M-PIRONAE GERMPLASM INTO ALFALFA (M-SATIVA), Genome, 36(3), 1993, pp. 594-601
This report describes the production and cytology of the first intersp
ecific hybrids between cultivated alfalfa (Medicago sativa L.) at the
diploid level (2n = 2x = 16) and the diploid (2n = 2x = 16) perennial
species M. daghestanica and M. pironae. An ovule-embryo culture techni
que was required to rescue hybrid embryos and all hybrids were diploid
. Predominately bivalent chromosome pairing was observed at meiotic me
taphase. All F1 hybrids were male and female sterile and no species ba
ckcross progeny could be produced. We discovered that trispecies hybri
ds could be efficiently recovered via crossing diploid F1 interspecifi
c hybrids of M. sativa X M. rupestris with either M. daghestanica or M
. pironae. Ovule-embryo culture was also required to recover these tri
species hybrids with recovery efficiency of trispecies hybrids about 1
0 times greater than for bispecies hybrids. Most chromosomes paired as
bivalents in the trispecies hybrids. Importantly, progeny can be reco
vered from crossing the trispecies hybrids with M. sativa. Therefore,
the M. sativa X M. rupestris hybrids provide a bridge cross to potenti
al introgression of M. daghestanica or M. pironae germplasm. Analysis
of randomly amplified polymorphic DNA (RAPD) markers in the trispecies
hybrids indicates that RAPD markers offer considerable potential for
assaying germplasm introgression following complex hybridizations of t
he type reported here.