中国春ph2b突变体×华山新麦草F_1自交和回交一代细胞遗传学研究

Cytogenetics Study of Chinese Spring ph2b mutant×Psathyrostachys huashanica Keng Selfing(S_1) and Backcross(BC_1)

用中国春ph2b突变体(Triticumaestivum L.cv.Chinese Spring)与华山新麦草(Psathyrostachys huashani-caKeng)杂种F1的部分进行自交,而另一部分与3个不同的普通小麦品种以及中国春ph2b突变体进行回交,并对自交和回交一代的形态学和细胞学进行研究。结果表明:(1)含有AABBDDNs的自交F2的花粉母细胞减数分裂中期Ⅰ平均单价体数都在7以上,说明来自华山新麦草的Ns基因组可引起普通小麦ABD基因组中某一个(几个)同源组发生不联会或联会消失;(2)在回交一代(F1×CS、F1×CSph2b)中,平均单价体数都在7以下,说明其中的ph2b基因起到了促进染色体配对的作用;而在回交一代(F1×J-11、F1×郑麦-9023)中,则表现正常,与理论一致;(3)在所有自交和回交一代中,减数分裂期间均出现染色体桥、落后染色体、三分孢子体、多分孢子体以及微核等各种染色体异常行为,说明Ns基因组引起了所得材料细胞学上的不稳定性。从总体上讲,回交比自交能更快地恢复ph2b基因促进部分同源染色体配对的作用,为染色体重组提供更多的机会,期望在后代中获得新种质。

Morphology and cytological behaviors of S1 and BC1 plants was studied. The results were as follows.（1）average univalents of S1 ,containing AABBDDNs genomes had more than 7 at MI during meiosis. This indicated that at least one chromosome of the Ns genome derived from P. huashanica, caused asynapsis or desynapsis of one ore more bivalents formed between homologues of the A,B or D genomes; （2）Average univalent of BC1 plants（F1× CS,F1× CSph2b）having less than 7,it may be introduced by ph2b gene, which can cause chromosome pairing; But average univalent of BC1 plants （F1×J-11, F1× Zhengmai-9023） had normal expected univalent numbers; （3） Various chromosome abnormalities were observed, such as chromosome bridges,lagging chromosomes, Tri- and polynucleate cells, micronuclei and so on, because of Ns genome both backcross and selfing plants were not steady in cytological. On the whole, backcross could reinstate the action of ph2b quicker than selfing. It could be advance for chromosome rearrangment, from this we expect to get new germplasm.