| Hainan Island was one of the main distribution area of Oryza rufipogon. However, habitat deterioration resulted in rapid reduction of O. rufipogon resource in Hainan. Not only a large number of natural populations disapeared, but also individuals within surviving populations substantially reduced. Furthermore, in recent years, more and more genetically modified rice breeded in Hainan without any isolation measures. The risk of transgene escape in Hainan was much higher than anywhere else in the country. In order to efficiently predict transgene escape and its potential ecological consequences, a better understanding of geographical distribution patterns, ecological differences, morphological characteristics, flowering habits, reproductive characteristics of O. rufipogon was necessary. So surviving populations of O. rufipogon in Hainan were studied on ecological environment and various biological characteristics. On this basis, differentiation of O. rufipogon populations from China was studied and influence of introgression from O. sativa on the O. rufipogon differentiation was discussed. The main findings were as follows:According to ecological environment, 11 populations of O. rufipogon in Hainan were divided into 6 ecotypes, namely marsh ecotype, shallow-water pond ecotype, hillside stream ecotype, paddy side pond ecotype, deep water bay ecotype and deep water marsh ecotype. The O. rufipogon populations were divided into two groups based on morphological characteristics. Group 1 exhibited longer and wider flag leaves, with lengths exceeding 30 cm. Panicles were longer and most exceeded 30 cm. An increase in spikelets per panicle relative to Group 2 was detected. Furthermore, more secondary branches were found in some populations. In Group 2, the following traits were observed: panicles less than 30 cm in length; fewer than 100 spikelets per panicle; and rare secondary branches in some populations.About the O. rufipogon population of Dong'ao, Wanning county, the flowering date of the eastern sub-population was 15 days earlier than the western subpopulation, and the flowering date of the eastern subpopulation met with the close-by regenerating O. sativa. Furthermore, flowering time between the eastern subpopulation and close-by regenerating O. sativa also met. The average seed setting rate was 8.7±6.74% in the eastern sub-population, while that in the western sub-population was 62.1±13.29%. Statistics showed that they had significant difference at 1% level. So the eastern subpopulation probably has been affected by the gene flow from closed-by regenerating O. sativa.Nucleotide diversity in 32 flowering-control gene fragments of O. rufipogon from Danzhou county and O. sativa (9311, Nipponbare) was investigated. There were 37011 invariable sites, 218 variable sites, 99 singleton variable sites, 119 parsimony informative sites and 370 indels sites. Variable sites could be divided into 3 types. Type 1 showed indica-japonica differentiation; type 2 differentiation between O. rufipogon and O. sativa; type 3 partial differentiation between O. rufipogon and O. sativa. Indica-japonica differentiation was the main variation type. The largest indels variation was found in OsGI-4 (255 gaps). OsGI-4 could accurately distinguish japonica from indica. All japonica varieties were the type of J (a band of 1.2kb), all indica varieties were the type of I (a band of 0.9kb) and the hybrid of japonica and indica were the type of J-I (both bands of 1.2kb and 0.9kb). Indica-japonica differentiation in O. rufipogon from China based on OsGI-4 was analysed. The result found that I (indica-type), J (japonica-type) and J-I were all observed in Chinese O. rufipogon. Japonica-type was the major type in China Mainland. Japonica- or indica-type was not significantly preponderant, but indica-type seemed to be more than japonica-type in Hainan Island. Based on 5 SSR markers who could detect hybridization of O. sativa and O. rufipogon, Cultivar specific alleles were found in almost all J-I O. rufipogon individuals, which suggested that introgression from O. sativa occurred in J-I O. rufipogon individuals. Further analysis implied that J-I individuals probably was the result of hybrid between japonica- or indica-type O. rufipogon and O. sativa indica or japonica. Emergence of J-I-type individuals in a population of O. rufipogon affected the original japonica or indica characteristic of the population.Two types of alternative splicing (970bp and 1170bp) were found in O. sativa japonica (Nipponbare), three (970bp, 1170bp and 1065bp) in O. sativa indica (9311), two (970bp and 1170bp) in O. rufipogon. In addition, the result of indica-japonica differentiation of O. sativa or O. rufipogon analysized by OsGI mRNA was consistent with the result by OsGI DNA. |
PDF Full Text Request