论文部分内容阅读
棉花种间杂种:G.hirsutum(2n=52)×G.thurbeti(2n=26),F_1的染色体数2n(3x)=39,属于三倍体,因而杂种植株高度不育。从花粉粒形态鉴定,大都是不规则形,其中正常园形的约占14％,但花药又不破裂。用染色剂测定其花粉生活力,不着色者占89％,浅红色者占11％,均为失活花粉。观察杂种F_1(3x)的花粉母细胞,在减数分裂时,染色体大都不配对,单价体数20个左右。而且分裂未期多数P.M.C形成具有5—12个的多分孢子体。这都表明雄性配子败育,导致杂种植株表现为高度不育。用秋水仙碱和DMSO等药物处理杂种枝条,获得染色体加倍的嫁接植株,镜检花粉母细胞,减数分裂的中期相,其二价染色体数为25—32对。分裂末期,形成正常四分体数占95％以上,花粉生活力也显著的提高,因此杂种株的育性得到一定的恢复。同时随着回交世代的延续,杂种育性逐渐提高。利用棉花种间杂种后代的多样性,从中选出抗病、抗虫高纤维强度等新类型,已供棉花育种应用。
Cotton hybrids: G.hirsutum (2n = 52) × G.thurbeti (2n = 26), chromosome number 2n (3x) of F_1 = 39, belong to triploid, and the hybrid plants are highly sterile. Identification from the pollen grain morphology, mostly irregular shape, of which about 14% of the normal park-shaped, anther without rupture. Pollen viability was measured with a stain, with 89% non-colored and 11% light red, all inactivated pollen. Pollen mother cells of F_1 (3x) hybrids were observed. At meiosis, the chromosomes were mostly unpaired with about 20 monovalent units. Moreover, the most frequent P.M.C splitting spawns with 5-12 sporozoites. This shows that male gametes abortion, resulting hybrid plants show a high degree of infertility. With colchicine and DMSO and other drugs to deal with hybrid branches to obtain doubled chromosome grafted plants, microscopic examination of pollen mother cells, meiotic metaphase, the number of bivalent chromosomes 25-32 pairs. At the end of division, the formation of normal tetrad number accounted for more than 95%, pollen viability also significantly increased, so the fertility of hybrid strains have been restored. At the same time, with the continuation of the backcross generation, hybrid fertility gradually increased. Taking advantage of the diversity of interspecific hybrids in cotton, new types such as disease resistance and insect resistance and high fiber strength were selected for cotton breeding.