UNREDUCED GAMETES IN PLANT BREEDING

Ciência Rural

Schifino-Wittmann, Maria Teresa²  Dall'Agnol, Miguel¹ 

[1] Universidade Federal do Rio Grande do Sul;Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil

关键词: unreduced gametes;    polyploidy;    plant breeding;    evolution;   

DOI  :  10.1590/S0103-84782001000100028

学科分类：农业科学（综合）

来源: Universidade Federal de Santa Maria * Centro de Ciencias Rurais

【 摘 要 】

The role of unreduced (2n) gametes, those with the somatic chromosome number, in the origin of polyploids and in plant breeding are reviewed. It is accepted that polyploids originated in nature rather by fusion of unreduced gametes than by somatic duplication. These gametes are formed by meiotic non-reduction, in the first division restitution (FDR) or in the second division restitution (SDR). They are normally found in natural populations in very low frequencies, with some remarkable exceptions, and are under genetic and environmental influence. Detection of 2n gametes, which are much more studied in male meiosis, is mainly accomplished by pollen grains size and detection of dyads and tryads at the end of meiosis II. Unreduced gametes are utilized in plant breeding in two ways: in uni or bilateral polyploidization, which maintains in the newly formed polyploid the heterozygosis lost through somatic duplication, and as a bridge to transfer desirable genes from wild diploid species into the cultivated polyploid genepool, by example in alfalfa. The manipulation of unreduced gametes should be considered as an important tool in plant breeding.

【 授权许可】

CC BY-NC