Genetic characterization of a new cytoplasmic male sterility system (hau) in Brassica juncea and its transfer to B. napus

Abstract

A novel cytoplasmic male sterility (CMS) was identified in Brassica juncea, named as hau CMS (00-6-102A). Subsequently, the male sterility was transferred to B. napus by interspecific hybridization. The hau CMS has stable male sterility. Flowers on the A line are absolutely male sterile, and seeds harvested from the line following pollinations with the maintainer gave rise to 100% sterile progeny. The anthers in CMS plants are replaced by thickened petal-like structures and pollen grains were not detected. In contrast, in other CMS systems viz. pol, nap, tour, and ogu, anthers are formed but do not produce viable pollen. The sterility of hau CMS initiates at the stage of stamen primordium polarization, which is much earlier compared with the other four CMS systems. We have successfully transferred hau CMS from B. juncea to B. napus. Restorer lines for pol, ogu, nap, and tour CMS systems were found to be ineffective to restore fertility in hau CMS. Sixteen out of 40 combinations of mitochondrial probe/enzyme used for RFLP analysis distinguished the hau CMS system from the other four systems. Among these sixteen combinations, five ones alone could distinguish the five CMS systems from each other. The evidence from genetic, morphological, cytological and molecular studies confirmed that the hau CMS system is a novel CMS system.

Comparative analysis of mitochondrial genomes between the hau cytoplasmic male sterility (CMS) line and its iso-nuclear maintainer line in Brassica juncea to reveal the origin of the CMS-associated gene orf288

“…Although it has relatively high similarity with orf263 in alloplasmic male sterile Brassica tournefortii at the nucleotide level, the restorer lines for tour CMS systems were found to be ineffective for restoring fertility in the hau CMS line. This may suggest that they were different from each other [22]. A comparative analysis of the mitochondrial genome of the hau CMS line and its maintainer line further confirmed that orf288 was CMS-associated gene in hau CMS line in B. juncea .…”

“…A cultivar trilocular line, J163-4, in B. juncea with fertility anther was also used as control in our study [39]. The anthers in the hau CMS plants are replaced by thickened petal-like structures and the sterility of the hau CMS initiates at the stamen primordium polarization stage [22]. Seeds from the hau CMS line, its iso–nuclear maintainer line and the normal type line “J163-4” were harvested in an experimental field at Huazhong Agricultural University in 2011.…”

“…The anthers in the hau CMS plants are replaced by thickened petal-like structures, and hau CMS sterility starts at the stamen primordium polarization stage, much earlier than the other four CMS systems used in Brassicas ( pol , ogu , nap , and tour ) [22]. A novel chimeric gene named orf288 was found to be located downstream of the atp6 gene and co-transcribed with this gene in the hau CMS sterile line.…”

Cytoplasmic male sterility in Brassicaceae crops

“…Xiangyu (Liu et al 2005) and hau in B. juncea (Wan et al 2008). Maintainer and restorer lines of 681A CMS are the same as those for pol , but 681A lines differ from pol lines in their mitochondrial genome organization, suggesting that 681A might be a variant of pol CMS.…”

“…Maintainer and restorer lines of 681A CMS are the same as those for pol , but 681A lines differ from pol lines in their mitochondrial genome organization, suggesting that 681A might be a variant of pol CMS. On the other hand, restorers for hau cytoplasm have not been identified so far and pol or nap restorers fail to rescue hau -induced male sterility (Wan et al 2008). …”