Yang Q, Hanson L, Bennett M D, Leitch I J
Jodrell Laboratory, Royal Botanic Gardens, Surrey, United Kingdom.
Genome. 1999 Jun;42(3):512-8.
Allohexaploid wild oat, Avena fatua L. (Poaceae; 2n = 6x = 42), is one of the world's worst weeds, yet unlike some of the other Avena hexaploids, its genomic structure has been relatively little researched. Consequently, in situ hybridisation was carried out on one accession of A. fatua using an 18S-25S ribosomal DNA (rDNA) sequence and genomic DNA from A. strigosa (AA-genome diploid) and A. clauda (CC-genome diploid) as probes. Comparing these results with those for other hexaploids studied previously: (i) confirmed that the genomic composition of A. fatua was similar to the other hexaploid Avena taxa (i.e., AACCDD), (ii) identified major sites of rDNA on three pairs of A/D-genome chromosomes, in common with other Avena hexaploids, and (iii) revealed eight chromosome pairs carrying intergenomic translocations between the A/D- and C-genomes in the accession studied. Based on karyotype structure, the identity of some of these recombinant chromosomes was proposed, and this showed that some of these could be divided into two types, (i) those common to all hexaploid Avena species analysed (3 translocations) and (ii) one translocation in this A. fatua accession not previously observed in reports on other hexaploid Avena species. If this translocation is found to be unique to A. fatua, then this information, combined with more traditional morphological data, will add support to the view that A. fatua is genetically distinct from other hexaploid Avena species and thus should retain its full specific status.
异源六倍体野生燕麦，即野燕麦（禾本科；2n = 6x = 42），是世界上最有害的杂草之一。然而，与其他一些燕麦属六倍体不同，其基因组结构的研究相对较少。因此，利用18S - 25S核糖体DNA（rDNA）序列以及来自栽培二粒小麦（AA基因组二倍体）和克劳德燕麦（CC基因组二倍体）的基因组DNA作为探针，对一份野燕麦材料进行了原位杂交。将这些结果与之前研究的其他六倍体的结果进行比较：（i）证实野燕麦的基因组组成与其他六倍体燕麦类群（即AACCDD）相似；（ii）确定了rDNA在三对A/D基因组染色体上的主要位点，这与其他燕麦属六倍体相同；（iii）揭示了在所研究的材料中，有八对染色体携带A/D基因组与C基因组之间的基因组间易位。基于核型结构，对其中一些重组染色体的身份进行了推测，结果表明其中一些可分为两种类型，（i）所有分析的六倍体燕麦物种共有的易位（3种易位），（ii）这种野燕麦材料中的一种易位，在其他六倍体燕麦物种的报道中未曾观察到。如果这种易位被发现是野燕麦所特有的，那么这一信息与更传统的形态学数据相结合，将支持野燕麦在遗传上与其他六倍体燕麦物种不同的观点，因此应保留其完整的物种地位。
