Construction And Evaluation Of The Pan-Centromeric Segment Substitution Lines Of Rice

Rice is one of the most important staple food worldwide.With the increase of the population,food safety has become a major issue all over the world.Meanwhile,with the improvement of living standards,rice quality and food safety have drawn people’s attention.The most direct and effective way to elevate rice quality is via rice variety improvement.One way to utilize a valuable genetic stock for gene discovery and rice breeding is by the Chromosome Segment Substitution Lines(CSSL)population,which is developed by backcross scheme with a recurrent parent and molecular marker selection of particular chromosomal segment from a donor parent.In the present study,we developed the pan-centromere substitution lines from the CSSL population with ZS97 as the recipient parent and NIP as the donor parent and evaluated several agronomic performances of the pan-centromere substitution lines,to examine the effects of pan-centromere regions on rice essential traits.The main results are listed as follows:1.From the CSSL population with NIP as donor parent and ZS97 as recipient,we selected the lines which contains NIP segment at pan-centromere regions for all the 12 chromosomes.Through multiple backcrossing with ZS97,combining with molecular marker detection and gene chip technology,we replaced the pan-centromere region of ZS97 with NIP,and developed the pan-centromere segment substitution lines each carrying only one introgression segment.2.The centromere is the key structure driving chromosomal distribution.In the present study we used the centromeric region heterozygous lines to construct segregation populations and to test segregation distortion at the target regions.We observed the segregation distortion on the pan-centromere regions of chromosomes 4,8,and 11.3.The 12 pan-centromere substitution lines were investigated in the agronomic traits including seed germination,plant growth and yield related traits,and the genetic effect of pan-chromatic regions was analyzed.Several agronomic traits such as plant height,grain yield per plant and grain weight per spikelet have significant difference from that in ZS97.4.Using one introgression line with the ZS97 background,we constructed an F2 segregation population,and screened for recombinant lines.Combining the agronomic traits(grain weight per spike,grain shape,plant height,etc.)with genotypes,we fine-mapped a QTL in a 90-Kb region for grain weight on chromosome 4.This region contains the gene An-1,which was already cloned displaying the regulation of several agronomic traits such as awn length,grain number per panicle grain length in rice.