八倍体小偃麦与普通小麦杂种自交和回交后代染色体和性状分离的研究

Segregation of Chromosomes and Traits in Selfing and Backcross Progenies of Hybrid between Octoploid Tritelytrigia and Triticum aestivum

以八倍体小偃麦小偃693和普通小麦烟农15的六个不同杂种世代为材料,研究了自交和回交对杂种后代染色体和性状分离的不同影响。结果表明,随自交和以烟农15为轮回亲本回交世代的增加,染色体数目逐渐减少,但回交比自交能使后代中偃麦草染色体丢失更快;回交后代PMC MI染色体构型较为简单,平均交叉结数减少,回交次数过多不利于偃麦草与普通小麦染色体发生遗传重组;自交和回交世代中小偃麦类型、中间类型和小麦类型出现频率明显不同,回交能显著提高后代中倾小麦类型的频率,明显改善杂种后代的农艺性状。杂种后代变异类型丰富,利用八倍体小偃麦与普通小麦杂交是将偃麦草的遗传物质导入普通小麦,选育具有偃麦草优良特点的新种质和新品系的有效方法。

Six different hybrid generations of the cross between Octoploid Tritelytrigia Xiaoyan 693 and common wheat Yannong 15 were used to study the effects of selfing and back-cross on the segregation of chromosomes and traits. The results indicated that the chromosome number decreased gradually as the generation advance of the selfing and the backcross (recurrent parent Yannong15). In the backcross generations the Agropyron chromosome lost fast, the chromosome configuration at MI in PMC became more simple and with less chiasmas than that in selfing generations. It suggested that many times of backcross was not helpful to the genetic recombination between Agropyron and common wheat chromosomes. On the other hand, the phynotypic types of all the hybrid offsprings were very plentiful, but the frequencies of the A-gropyron type, the wheat type and the middle type were obviously different between the selfing and backcross generations. The backcross significantly increased the frequency of wheat type and improved the agronomic traits of offsprings. These indicated that the cross between Octoploid Tritelytrigia and common wheat was efficient to introduce new germplasms into the common wheat and select new strains with the good characters of Agropyron.