Identification Of Chromosome Segment Substitution Linesand Rapid Chlorophyll Fluorescence Analysis Of Oryza.longis Taminata

Rice is one of the most important food crops.It is a very effective way to improve rice varieties by expanding the genetic base of cultivated rice with wild rice.Oryza longistaminata is a wild rice with AA genome,which contains unique traits not found in cultivated rice.In order to excavate and study favorable genes in O.longistaminata,246 molecular markers with polymorphism between O.longistaminata and Oryza sativa spp.indica cultivar Huanghuazhan were used to identify the whole genome of chromosome segment substitution lines(CSSL)derived from the materials.Combined with phenotypic analysis,QTL analysis was carried out for the main agronomic traits of CSSL.The photosynthetic characteristics of O.longistaminata were analyzed by rapid chlorophyll fluorescence technique.The main results are as follows:(1)On the basis of 203 previous polymorphic molecular markers,43 polymorphic markers were newly screened and identified in this study.There were an average of 20.5 molecular markers on each chromosome,and the average physical spacing of these markers was 1.55 Mb.(2)The whole genotype of 73 substitution lines was identified with 246 polymorphic markers.It was found that the chromosome segments from O.longistaminata(hereafter referred to as the imported fragment)covered 189.6Mb of rice genome,with a coverage rate of 54.1%.On average,each CSSL had 6.9 imported fragments,9.8 Mb imported fragments,and 97.2%background response rate.Based on 45.9%of the uncovered areas,seven CSSLs were amplified by identifying and backcrossing low-generation rice materials.(3)Statistical analysis of main agronomic traits of 73 substitution lines showed that,The number of CSSL were 8,10,62,31,3,1,2,3,1,1,37 and 12,which were significantly different from the recipient cultivar Huang Huazhan in plant height,flag leaf length,flag leaf width,flag leaf area,flag leaf aspect ratio,number of primary branches per panicle,grain number per panicle,seed setting rate,grain width,grain length/width ratio,100 grain weight and effective tiller number,respectively.(4)42 QTLs were obtained from CSSLs,and have 22,5,1,1,9,3 and 1 QTLs affected plant height,flag leaf shape,effective tiller number,number of primary branches per panicle,fertility,grain shape and grain weight,respectively.(5)Rapid chlorophyll fluorescence analysis showed that compared with cultivar Huanghuazhan,O.longistaminata had higher light energy absorption and conversion efficiency(φPo、φEo、φDo),and could absorb and transform more light energy per unit area(ABS/CSm、TRo/CSm、ETo/CSm).It has a high density of reaction centers(RC/CSo、RC/CSm).The F1 generation inherited the fast chlorophyll fluorescence characteristic of O.longistaminata.