Ogura CMS紫菜苔与萝卜双二倍体的获得及细胞遗传学研究

Production and cytogenetics of amphidiploids between Ogura CMS Brassica campestris var. purpuria and Raphanus sativus

以Ogura CMS紫菜苔(AA,2n=20)为母本,以不同萝卜品种(RR,2n=18)为父本进行杂交,获得了大量的属间杂种。从杂种F_1中发现了2株染色体自然加倍的双二倍体。在形态上双二倍体与未加倍的杂种F_1相似,都表现父本萝卜的白花性状,蜜腺正常,低温下子叶及真叶均不缺绿。在减数分裂中期Ⅰ双二倍体多数细胞形成19个二价体,后期Ⅰ时染色体以19:19的方式分配到两极,最后形成具有19条染色体的配子。通过对可染花粉比例、全株种子粒数及平均每个有效角果种子粒数的比较发现,虽然双二倍体的花药比未加倍的杂种F_1发育要好得多,但是双二倍体的育性还是低于未加倍的杂种F_1,尽管未加倍的杂种F_1在减数分裂时多数染色体以单价体的形式存在,同时也有二价体、三价体甚至四价体的形成,并且存在落后染色体和染色体桥。推测Ogura CMS紫菜苔×萝卜属间杂种F_1的育性除了减数分裂染色体的配对有关之外,与双亲染色体上基因的相互作用也有重要关系。对该杂种的遗传及育种意义进行了讨论。

Crosses between Ogura CMS Brassica campestrisvar. purpuraria (AA,2 n =20) and Raphanus sativus (RR,2 n = 18) were made and many intergeneric hybrids were produced. Two amphidiploids (AARR, 2 n = 38) were found from the FI . The amphidiploids were similar to common F, plants in morphology, eg., the seedlings did not show chlorosis at low temperature, all the F1 plants had white flowers and normal honey glands, but the anthers of the amphidiploids were better than those of the common F1 . During meiosis most cells of the amphidiploids formed 19 bivalents, which were divided evenly to the two poles and gametes with 19 chromosomes were produced, but the fertility of the amphidiploids were much lower than F1 without chromosome doubling, although most chromosomes of the F1 without chromosome doubling exsisted as univalents at metaphase I , and there were laggards and chromosome bridges at anaphaes I . It was supposed that fertility of the intergeneric hybrids was influenced by the interaction of genes on thromosomes of the two parents as well as cytological irregularities.