| Rice is one of the most important grain crops in China.However,in recent years,been the homologous of rice,weeds rice is the serious threat to the growth and production of ricebecause the popularization of simplified cultivation techniques,direct seeding and the reduction in labour input.Jiangsu and Guangdong are not only as the main producing areas of rice in China,but the three-lines indica-type hybrid rice growing provinces.Meanwhile,they are also the the worst damaged areasby weedy rice in our country.The research focused on the following parts:1.Design of a specific CMS-WA marker.It is easily to find the mixtures of conventional cultivated rice,three-line indica-type hybrid rice and weedy rice in the same field when we surveyed the occurrence and damage of weedy rice.Thus,it is necessary to exploit a marker in order to distinguish cultivated rice,three-line indica-type hybrid rice and weedy rice effectively.Using Primer Premier 5.0 software to design primers,according to the CMS-WA gene cloned from ZS97A within the 287-439 bp,which is the major difference of CMS-WA gene between three-line indica-type hybrid rice and conventional rice varieties.Finally,a specific markers WA7(Forward:5-TTTGCCTTATTTTGACCTGTTTGA-3;Reverse:5-TACTTTCAGGAGGGGAGGCA-3)was found in the region.PCR product sequencing showed that the length of WA7 fragment amplified was 75bp.2.Test the hypothesis that weedy rice in Jiangsu province originated from three-line idica-type hybrid rice.The proportion of CMS-WA gene in 63 weedy rice populations(1232 samples)of Jiangsu province were detected by using a combination markers WA7/RED4.The results showed that4 weedy rice of 1232 samples contained CMS-WA gene,which mainly existed in JSYZ3,JSYZ6 and JSSZ1 groups,only accounting for 0.3247%of total samples.which indicated that there-line indica hybrid rice is not the main source of weedy rice in Jiangsu province.3.Analysis of genetic diversity and propagation pathway of weedy rice in Guangdong Province.Using 30 pairs of co-dominant SSR markers to analyse the genetic structure and UPGMA cluster analysis of weedy rice samples from middle-north,middle-south,south-west sampling sites in Guangdong province,to understand the propagation pathway of Weedy Rice in Guangdong Province.1)78 alleles,26 polymorphic loci,accounting for 86.67%were detected in 847 weedy rice samples in Guangdong province by using 30 pairs of SSR markers.The average number of alleles(Na),effective number of alleles(Ne),Shannon diversity Index(I),observed heterozygosity(Ho)and expected heterozygosity(He)were 2.6,1.5842,0.511,0.0236 and 0.2968 respectively.Compared with the level of genetic diversity of other selfing annual plants(0.23),the weedy rice in Guangdong province showed higher genetic diversity.2)The observed heterozygosity index(Ho)ranged from 0 to 0.1169 in 42 weedy rice populations,which was relatively low on theeneral level.It showed that there were significant differences existedand population genetic differentiation occurred between various groups.The inbreeding coefficient within individuals relative to the total(Fit=0.8264)was relatively high and the outcrossing rate(t=0.0426)was relatively high,which showed that heterozygous gene in Guangdong province is small amount,mainly in inbred breeding.The average of the inbreeding coefficient within individuals relative to the population(Fis=0.8247)and the average of the inbreeding coefficient within populations relative to the total(Fst= 0.5044)indicated that the degree of genetic variation within colonies was more prominent than that within population.The AMOVA analysis reverled the similar results.The gene flow(Num)between three planting area was from 0.193 to 0.3305,average was 0.2519 and all of the values were below 1?which indicated the genetic differentiation of weedy rice between three different areas was significant.3)Mantel test analysis showed that 42 weedy rice populations in Guangdong province was no significant correlation(R2=0.0113,P=0.116)with their geographic distance.The AMOVA analysis showed that the genetic differentiation was only 4%between different planting areas.The UPGMA results revealed that the weedy rice could be divided into 4 groups,two groups were composed of weedy rice populations from middle-south planting area,while the other two groups were mixed from three different planting area.In conclusion,the research suggested that weedy rice populations in Guangdong province were not occurred independently in every planting area but area-to-area transmission.4.The recent source of weedy rice in Guangdong province.847 weedy rice samples(42 populations)and 160 control samples which contained the conventional cultivated rice,three-line indica-type hybrid rice,common wild rice and local cultivated rice were analyzed by Structure and UPGMA clustering and genetic structure analysis using 30 pairs of co-dominant SSR markers.The results revealed weedy rice in Guangdong province has closer relationship with conventional indica rice,three-line indica hybrid rice and the cultivated rice collected from the corresponding fields,but the relationship with the conventional japonica rice and common wild rice was more distant.Structure analysisget the similar results.In summary,we speculated that weedy rice in Guangdong province maybe derived from rice rather than from common wild rice. |
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