Development Of Chromosome Segment Substitution Lines Carrying Japonica Segments In Indica Baekground And Genetic Effect Analysis Of The Introgress Segments

Rice is one of the most important crops in the world, and increasing its production has been the focus of scientists. Over last several years, scientists have been committed to explore the potential of rice production by using various strategies, and have made remarkable achievements. Single segment substitution lines (SSSLs) are a set of near isogenic lines that could be generated by hybridization, backcross, selfing and introgressing of marker-defined donor segments in the recurrent parent background. SSSLs are the ideal state of chromosome segment substitution lines (CSSLs) for (minor) QTL exploring, fine mapping and cloning. In this study, a set of CSSLs carrying japonica cv. Nippobare (NP) segments in the uniform genetic background of indica cv. ZhenShan 97B (ZS97B) was used. The purpose is to construct an ideal SSSLs population (e.g. higher background response rate, fewer non-target segments through marker-aided selection. In addition, the CSSLs were also used to detect yield-related QTL. The main results are as follows:1. A series of 82 CSSLs were generated by subsequent backcrossing, and 175 polymorphic SSR markers distributing evenly on 12 rice chromosomes were used for genotyping. Each line carried an averge of three segements, and 23 of 82 CSSLs contained a single segment. All CSSLs had the genome proportion of the recurrent parent ranging from 91.6% to 99.8%, with an average of 97.4%. The segment of NP spanned an average of 37.6 cM and the total length was 3133.5 cM that was 2.2 times of rice genome.2. Phenotypic evaluation of 9JP and TP populations were carried out in two continuous years. The traits characterized were plant height (PH), heading date (HD), panieles per plant (PPP), number of primary branches (PB), number of secondary branches (SB), panicle length (PL), panicle weight (PW), kilo-grain weight (KGW), spikelets number per panicle (SN), seed setting ratio (SSR) and yield per plant (YD). Transgressive segregations observed in all these traits showed that the introgressed NP segments had an effect on agronomic traits, and all the traits showed significantly normal distribution. The results suggested that the traits were quantitative traits controlled by multiple minor genes.3. A total of 67 QTLs, which distributed on 11 rice chromosomes (except chromosome 9), were detected in the 9JP population.79 QTLs, which distributed on other 11 rice chromosomes (except chromosome 12), were detected in the TP population. Totally twelve QTLs were detected common in the two populations. 4. The 23 SSSLs showed that the average length of thesubstituted segments was 17.2 cM, and the total length was 395.3 cM, covering 27.2% of the whole genome. Totally 24 QTLs, which were detected in 11 out of the 23 substituted segments, located on chromosome 1,2,5,7 and 8, respectively.