Cytological observation of anther structure and genetic investigation of a new type of cytoplasmic male sterile 0A193-CMS in Brassica rapa L.

摘要

Cytoplasmic male sterility (CMS), a maternally transmitted failure in pollen formation, is an effective pollination control system in hybrid rapeseed (Brassica napus) breeding. However, CMS is not widely used in the related oilseed species Brassica rapa. In the past years, several male sterile plants have been isolated from the B.rapa landrace 0A193', collected in Shaanxi, China, in 2011. It is noteworthy that the fertility expression of 0A193-CMS was affected by temperature. In contrast to pol CMS, fertility tests with 18 B.rapa and 9 B.napus accessions suggest that a different system of maintaining and restoring is responsible for the observed phenotype. Further on, genetic investigation evidenced that fertility of 0A193-CMS is controlled by both cytoplasmic and one pair of nuclear recessive genes. Interestingly, plants of the 0A193-CMS type possess a highly specific fragment of the mitochondrial gene orf222, a crucial regulator of male sterility in nap CMS. Our study broadens the CMS resources in B.rapa and provides a highly applicable alternative to pol CMS and ogu CMS for hybrid breeding production.