Determination Of The Gene Responsible For Rice Wide-compatibility

Strong heterosis has been observed in rice inter-subspecific hybrids, however, such heterosis could not find its application in rice production due to an occurrence of semi-sterility spikelets. Fortunately, the rice breeders found some very unique varieties, called wide-compatibility varieties, that could lead to normal fertility in the hybrids when crossing to either indica or japonica rice subspecies. This discovery made it possible to utilize the strong heterosis of inter-subspecific hybrids. The S5n gene, located on chromosome 6, has previously been manifested to be responsible for the wide-compatibility in rice.In our previous report, the S5n gene has been mapped within a 50 kb interval delimited by the left marker J13 and the right marker J17. Sequence analysis of the 50 kb region revealed two candidate genes, coding an aspartyl protease and a hypothetical protein. In the present study, we constructed the two kinds of express vectors, over-expression vector and functional complementary test vector, for each candidate gene. All the express vectors were transformed into the rice receptors for determining the gene responsible for the wide-compatibility in rice.The results for transformation are summarized as follows:1. By using the'Balilla×Nanjing11'F1 hybrid seeds as receptors, six transgenic lines were obtained and grew in Hainan winter nursery for investigating the spikelet fertilities. Comparing the transgenic lines with the candidate genes with those transformants carrying no vector, no any difference has been observed in the...