Characterization of the Mitochondrial Genome of a Wheat AL-Type Male Sterility Line and the Candidate CMS Gene

• Main Authors: Miaomiao Hao, Wenlong Yang, Weiwen Lu, Linhe Sun, Muhammad Shoaib, Jiazhu Sun, Dongcheng Liu, Xin Li, Aimin Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: International Journal of Molecular Sciences
• Subjects: AL18A; T-CMS; tapetum PCD; mitochondrial genome; <i>orf279</i>
• Online Access: https://www.mdpi.com/1422-0067/22/12/6388

Heterosis utilization is very important in hybrid seed production. An AL-type cytoplasmic male sterile (CMS) line has been used in wheat-hybrid seed production, but its sterility mechanism has not been explored. In the present study, we sequenced and verified the candidate CMS gene in the AL-type sterile line (AL18A) and its maintainer line (AL18B). In the late uni-nucleate stage, the tapetum cells of AL18A showed delayed programmed cell death (PCD) and termination of microspore at the bi-nucleate stage. As compared to AL18B, the AL18A line produced 100% aborted pollens. The mitochondrial genomes of AL18A and AL18B were sequenced using the next generation sequencing such as Hiseq and PacBio. It was found that the mitochondrial genome of AL18A had 99% similarity with that of <i>Triticum timopheevii</i>, AL18B was identical to that of <i>Triticum aestivum</i> cv. Chinese Yumai. Based on transmembrane structure prediction, 12 <i>orfs</i> were selected as candidate CMS genes, including a previously suggested <i>orf256</i>. Only the lines harboring <i>orf279</i> showed sterility in the transgenic <i>Arabidopsis</i> system, indicating that <i>orf279</i> is the CMS gene in the AL-type wheat CMS lines. These results provide a theoretical basis and data support to further analyze the mechanism of AL-type cytoplasmic male sterility in wheat.