McCoy T J, Echt C S
Department of Plant and Soil Science, Montana State University, Bozeman 59717-0312.
Genome. 1993 Jun;36(3):594-601. doi: 10.1139/g93-080.
This report describes the production and cytology of the first interspecific hybrids between cultivated alfalfa (Medicago sativa L.) at the diploid level (2n = x = 16) and the diploid (2n = 2x = 16) perennial species M. daghestanica and M. pironae. An ovule-embryo culture technique was required to rescue hybrid embryos and all hybrids were diploid. Predominately bivalent chromosome pairing was observed at meiotic metaphase. All F1 hybrids were male and female sterile and no species backcross progeny could be produced. We discovered that trispecies hybrids could be efficiently recovered via crossing diploid F1 interspecific hybrids of M. sativa x M. rupestris with either M. daghestanica or M. pironae. Ovule-embryo culture was also required to recover these trispecies hybrids with recovery efficiency of trispecies hybrids about 10 times greater than for bispecies hybrids. Most chromosomes paired as bivalents in the trispecies hybrids. Importantly, progeny can be recovered from crossing the trispecies hybrids with M. sativa. Therefore, the M. sativa x M. rupestris hybrids provide a bridge cross to potential 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 hybridization of the type reported here.
本报告描述了二倍体水平（2n = x = 16）的栽培苜蓿（紫花苜蓿）与二倍体（2n = 2x = 16）的多年生物种达吉斯坦苜蓿和皮罗内苜蓿之间首次种间杂交种的产生及细胞学情况。需要采用胚珠 - 胚培养技术来拯救杂种胚，且所有杂种均为二倍体。在减数分裂中期观察到主要是二价染色体配对。所有F1杂种均雌雄不育，无法产生种间回交后代。我们发现，通过将紫花苜蓿与卢佩斯特里斯苜蓿的二倍体F1种间杂种与达吉斯坦苜蓿或皮罗内苜蓿杂交，可以有效地获得三物种杂种。同样需要胚珠 - 胚培养来获得这些三物种杂种，三物种杂种的获得效率比二物种杂种高出约10倍。在三物种杂种中，大多数染色体配对形成二价体。重要的是，三物种杂种与紫花苜蓿杂交能够获得后代。因此，紫花苜蓿与卢佩斯特里斯苜蓿的杂种为达吉斯坦苜蓿或皮罗内苜蓿种质的潜在渗入提供了一个桥梁杂交。对三物种杂种中随机扩增多态性DNA（RAPD）标记的分析表明，RAPD标记在检测本文报道的这种复杂杂交后的种质渗入方面具有很大潜力。
