Use of Hybrid Rice and the Proliferation of Weedy Rice: A Case in Jiangsu, China

摘要

Jiangsu Province, located between northern China and southern China, is a typically mixed area of conventional and three-line hybrid rice without Oryza rufipogon Griff. and Oryza nivara S. D. Sharma & Shastry. In the recent decade, occurrence of weedy rice rapidly increased year by year since it was found and reported from 2000. The recent cloning of the CMS-WA gene (wild abortive cytoplasmic male sterility) makes it possible to design a marker specific for the gene for testing large quantities of weedy rice samples in a single assay by polymerase chain reaction (PCR). Through performing a BLAST search in the National Center for Biotechnology Information (NCBI) database using the sequence of the CMS-WA gene cloned from ZS97A as a reference, the major difference between three-line hybrid rice and conventional rice cultivars was found in the 287 to 439 bp region of the CMS-WA gene. A specific marker, WA7, was designed and evaluated for this region of the CMS-WA gene. This marker, in combination with RED4, a specific marker for the Rc red pericarp gene, was used to distinguish weedy rice, three-line hybrid rice, and conventional rice in a single PCR assay. A total of 1232 accessions of weedy rice collected from 63 locations in Jiangsu Province, China, were evaluated using the red pericarp and CMS-WA DNA markers. Only four accessions from three locations were found positive for the CMS-WA gene, accounting for just 4.76 and 0.32% of all locations and accessions, respectively. These results indicate that the three-line hybrid is likely a source but not the major source of weedy rice in Jiangsu Province.