Kamstra S A, Ramanna M S, de Jeu M J, Kuipers A G, Jacobsen E
Laboratory of Plant Breeding, The Graduate School of Experimental Plant Sciences, Wageningen Agricultural University, The Netherlands.
Heredity (Edinb). 1999 Jan;82 ( Pt 1):69-78. doi: 10.1038/sj.hdy.6884650.
A distant hybrid between two diploid species (2n = 2x = 16), Alstroemeria aurea and A. inodora, was investigated for homoeologous chromosome pairing, crossability with A. inodora and chromosome transmission to its BC1 offspring. Fluorescence in situ hybridization (FISH) with two species-specific probes, A001-I (A. aurea specific) and D32-13 (A. inodora specific), was used to analyse chromosome pairing in the hybrid and the genome constitution of its BC1 progeny plants. High frequencies of associated chromosomes were observed in both genotypes of the F1 hybrid, A1P2-2 and A1P4. In the former, both univalents and bivalents were found at metaphase I, whereas the latter plant also showed tri- and quadrivalents. Based on the hybridization sites of DNA probes on the chromosomes of both parental species, it was established that hybrid A1P4 contains a reciprocal translocation between the short arm of chromosome 1 and the long arm of chromosome 8 of A. inodora. Despite regular homoeologous chromosome pairing in 30% of the pollen mother cells, both hybrids were highly sterile. They were backcrossed reciprocally with one of the parental species, A. inodora. Two days after pollination, embryo rescue was applied and, eventually, six BC1 progeny plants were obtained. Among these, two were aneuploids (2n = 2x + 1 = 17) and four were triploids (2n = 3x = 24). The aneuploid plants had originated when the interspecific hybrid was used as a female parent, indicating that n eggs were functional in the hybrid. In addition, 2n gametes were also functional in the hybrid, resulting in the four triploid BC1 plants. Of these four plants, three had received 2n pollen grains from the hybrid and one a 2n egg. Using FISH, homoeologous crossing over between the chromosomes of the two parental species in the hybrid was clearly detected in all BC1 plants. The relevance of these results for the process of introgression and the origin of n and 2n gametes are discussed.
对两个二倍体物种（2n = 2x = 16），即金黄六出花（Alstroemeria aurea）和无香六出花（A. inodora）之间的远缘杂种进行了同源染色体配对、与无香六出花的杂交亲和性以及向其BC1代后代的染色体传递情况的研究。使用两种物种特异性探针，即A001 - I（金黄六出花特异性）和D32 - 13（无香六出花特异性）进行荧光原位杂交（FISH），以分析杂种中的染色体配对及其BC1代子代植株的基因组构成。在F1杂种的两种基因型A1P2 - 2和A1P4中均观察到高频率的关联染色体。在前者中，中期I发现了单价体和二价体，而后者植株还出现了三价体和四价体。基于DNA探针在两个亲本物种染色体上的杂交位点，确定杂种A1P4在无香六出花的染色体1短臂和染色体8长臂之间存在相互易位。尽管在30%的花粉母细胞中同源染色体配对正常，但两个杂种均高度不育。它们与亲本物种之一无香六出花进行了正反交。授粉两天后，进行了胚胎拯救，最终获得了六株BC1代子代植株。其中，两株为非整倍体（2n = 2x + 1 = 17），四株为三倍体（2n = 3x = 24）。当种间杂种用作母本时产生了非整倍体植株，这表明杂种中的n卵是有功能的。此外，2n配子在杂种中也有功能，从而产生了四株三倍体BC1植株。在这四株植株中，三株从杂种中获得了2n花粉粒，一株获得了2n卵。使用FISH技术，在所有BC1植株中均清楚地检测到杂种中两个亲本物种染色体之间的同源交叉。讨论了这些结果对于渐渗过程以及n和2n配子起源的相关性。
