太空诱变玉米核不育突变体矮化的遗传及外施赤霉素分析

Genetic analysis and gibberellins treatment effects on dwarfism of maize genic male sterile mutant induced by space flight

关键词:  太空诱变, 玉米, 细胞核雄性不育, 矮化, 遗传, 赤霉素

Key words:  space flight, maize, genic male sterility, dwarfism, genetic, gibberellins

摘要:

为了解太空诱变玉米核不育突变体矮化的遗传规律和原因,该研究以不育突变体为母本,自交系178、478为父本,对测交F₁、F₂群体进行育性鉴定和株高分析,对F₂可育株进行基因型和株高分析,对姊妹交后代分离群体进行育性鉴定和株高、雄穗长度、节间数、节间长度分析,同时,还对姊妹交后代分离群体进行施赤霉素处理,调查育性和株高的变化。结果表明:178和478背景下的F₁表现出与测交母本一样的极显著差异; 在178和478核背景下的F₂中,不育株株高极显著矮于可育株,两核背景下的不育株间株高差异不显著,而可育株间株高差异极显著; F₂中纯合和杂合可育株的株高差异不显著; 姊妹交后代分离群体中不育株株高、雄穗长度、节间数和节间长度极显著小于可育株; 外施赤霉素的不育株在苗期表现出对赤霉素一定的敏感性,但株高最终未恢复正常高度。因此,得出该突变体矮化表现稳定,与不育性状并存,且不受细胞核背景的影响; 核不育基因对植株株高的矮化无剂量效应; 突变体的矮化与雄穗长度、节间数和节间长度有关; 突变体不完全属于赤霉素不敏感型,其矮化并不是单一缺乏赤霉素而引起。该研究结果为认识太空诱变玉米核不育突变体矮化的遗传和生理机制提供了参考。

Abstract:

Male sterility provides an effective way for maize hybrids production. Plant dwarfism is one of the important target traits in crop breeding. Maize research institute of Sichuan Agricultural University obtained a genic male sterile mutant induced by space flight which was controlled by a pair of recessive genes. This mutant has the traits of sterility and dwarfism both needed by breeding. In order to find the genetic rules and reasons of dwarfism of the maize genic male sterile mutant, taking this sterile mutant as mother and inbred lines 178, 478 as father, fertility identification and plant height analysis of test cross F₁, F₂, genotype and plant height analysis of fertile F₂, fertility identification and plant height, tassel length, internode number and internode length analysis of sister cross off-springs were done. Meanwhile, gibberellins were applied on sister cross off-springs, fertility and plant height of which were examined. The results were as follows: The plant height difference of F₁ at the background of 178 and 478 which was significant was the same with that between 178 and 478; Sterile plant height was significantly lower than fertile plant height in F₂ at the background of 178 or 478, and the difference of sterile plant heights was not significant in F₂ at the background of 178 and 478, while the difference of fertile plant heights was significant; In fertile F₂ at the background of 178 or 478 of which the off-springs' fertility separated, the difference between homozygous and heterozygous plant heights was all not significant; In sister cross off-springs, separation ratio of fertile and sterile plants met 1:1, and sterile plant height, tassel length, internode number and internode length were significantly less to those of fertile plant; Exogenous application of gibberellins did not affect the fertility of sterile plants, and the sterile plants showed certain sensitivity to gibberellins at seedling stage, but the plant height of which did not restore to normality finally. Collectively, it was obtained that the dwarfism of this sterile mutant existing with the sterile trait was stable and not affected by nuclear background; There was no dose effect of nuclear male sterile gene on the dwarfism of plant height; Plant height difference of sterile and fertile plants was associated with tassel length, internode number and internode length; The sterile plant did not completely belong to gibberellins reduced response type, the dwarfism of which was not caused only by lack of gibberellins. The recessive gene controlling this male sterile mutant has been mapped at bin 3.06 of the maize third chromosome long arm and it is reported that there are also two maize dwarfism genes at this location. So, it was supposed that the abortion and dwarfism traits of this mutant were possibly regulated by a pleiotropic gene or two recessive genetic linkage genes, and the gene controlling plant height would produce a series of chain reaction, ultimately affecting the content of endogenous gibberellins and being regulated by exogenous gibberellins at certain developmental stages. These research results provide a reference for us to further understand the genetic and physiological mechanism of dwarfism of this mutant.