Application of aneuploid plants to plant breeding in genus Nicotiana

非整倍体在许多植物的遗传研究中都很有用，并有可能用于植物育种。首先，为了研究在二倍体和单倍体补体上增加一条额外染色体对基因平衡的影响，在烟叶（Nicotiana sylvestris） （n=x=12）上进行了三体（2n+1）和二体单倍体（n+1）植株的生产实验。将介于三倍体和二倍体之间的F_1植株与二倍体植株回交。从B_1后代中筛选出61株三体植株。这些三体植物根据叶形和花形态可分为12个类型。利用12种三组体进行花药培养。在获得的二体单倍体中，有5种植物发育了花器官。B220三体植株的二体单倍体花明显小而畸形，而相应的三体植株的花和叶比正常的二倍体正常且明显大。因此，三体系B220将是一个非常有用的品种。然而，在种子繁殖的物种中，额外染色体的低传递阻止了这些植物成为农业上有用的栽培品种。在B220系中，2n × 2n+1杂交的额外染色体转移率很低。这是由于n+1粒花粉发育迟缓，在开花时还没有完全成熟。在2n × 2n+1杂交中，延迟1天授粉和通过尼龙网选择的小花粉粒授粉增加了额外染色体的转移。其中，30 m和25 m尼龙网花粉的额外染色体转移率最高，分别为51.9%和70.4%。其次，在培养前用x射线等物理诱变剂处理B220二体单倍体花药中的花粉粒，可能是诱导染色体片段重复的有效方法，从而诱导出大的叶和花。基因组加倍可以在重复的染色体片段中产生纯合子植株。我们发现，经x射线处理的花药在植株中引起了许多染色体畸变。然而，到目前为止，还没有单个植物具有对农艺性状有用的染色体片段重复。看来，为了试图产生一种在农业上有用的特定复制，将需要大量的易位。少

Aneuploids have been useful for studying the genetics of many plant species and have possibility to be used for plant breeding. Firstly, in order to investigate the genic balance influenced by addition of an extra chromosome to diploid and haploid complements, an experiment was carried out on the production of trisomic (2n+1) and disomic haploid (n+1)plants in Nicotiana sylvestris (n=x=12). F_1 plants between triploid and diploid were backcrossed with the diploid plants. Sixty one trisomic plants were selected from the B_1 progenies. These trisomic plants were grouped into 12 types by the leaf shape and flower morphology. The anther culture was performed using the 12 types of trisomics. Among the obtained disomic haploids 5 types of plants developed frower organ. The flower of disomic haploid derived from B220 trisomic plant was conspicuously small and malformed, while the corresponding trisomic plant produced normal and remarkably larger flowers and leaves than the normal diploid. Thu … More s , trisomic line B220 will be very useful as a cultivar. However, in seed-propagated species, the low transimission of the extra chromosome has prevented such plants from becoming agriculturally useful cultivars. In line B220, the transfer of the extra chromosome in 2n x 2n+1 crosses was very low. This was due to the delayed development of n+1 pollen grains, which are not full maturity at the time of anthesis. The transfer of the extra chromosome in 2n x 2n+1 crosses was increased by a 1 day delay in pollination and also by pollination of small pollen grains selected through nylon meshes. Especially, pollen selected by using 30 and 25 m nylon meshes induced an extremely high transfer of the extra chromosome, namely 51.9% and 70.4%, respectively. Secondly, pollen grains in the anthers of disomic haploids of B220 treated before culture with physical mutagen such as X-rays, may be a useful method to induce the duplication of a chromosome segment which induces large leaf and flower. Doubling of genome may result in homozygous plantlets in the portion of duplicated chromosome segment. We realized many chromosome aberrations in plantlets induced by the anther treated by X-rays. No single plant with a useful duplication of the chromosome segment for agronomic character, however, has been achieved until now. It seems that in order to attempt to produce a specific duplication which is useful agriculturally, a huge number of translocations will be required. Less