生物
细胞质雄性不育
遗传学
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基因
基因组
不育
同源(生物学)
同步
分子生物学
肽序列
作者
Wooseong Ahn,Sunggil Kim
出处
期刊:Euphytica
[Springer Nature]
日期:2023-01-24
卷期号:219 (2)
标识
DOI:10.1007/s10681-023-03158-5
摘要
Cytoplasmic male sterility (CMS) has been exclusively used as an emasculation tool in seed production of hybrids in onion (Allium cepa L.).Three types of onion CMS (CMS-S, CMS-R, and CMS-T) have been used in hybrid onion breeding. Male sterility conferred by both CMS-S and CMS-R is likely induced by open reading frame (orf) 725, a chimeric gene. However, this gene was not detected in onion accessions containing CMS-T cytoplasm. Instead, a region showing high homology with orfA501, which is located in the 3’ end of orf725, was detected in CMS-T. A novel chimeric gene, which we named orf219, was identified by genome walking PCR amplification based on the orfA501 homolog. The 684-bp open reading frame of orf219 consisted of an 128-bp of exon 1 of atp1 and a 556-bp sequence of an orfA501 homolog. The high-copy-number orf219 was detected only in the CMS-T cytoplasm (T cytotype). Analysis of RT-PCR products showed normal transcription of orf219 and eight RNA editing sites, one of which created a stop codon, resulting in a shorter amino acid sequence upon translation. Sequences of four hypervariable regions in the chloroplast genome and the organization of syntenic blocks in mitochondrial genome indicated that CMS-T was very closely related to the normal (N) male-fertile and CMS-R cytotypes. Based on these findings, new molecular markers were developed for the identification of cytotypes CMS-T, -R, -S, and -N. Cytotypes of 424 diverse onion accessions were identified using six molecular markers. The CMS-S and CMS-R cytotypes predominated among the analyzed accessions. In contrast, only five accessions possessed CMS-T, supporting earlier reports that CMS-T is rarely used in hybrid-onion breeding.
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