Development Of Chromosome Segment Substitution Lines Using O.Rufipogon As Donor And Fine Mapping Of SPAD-QTL In Rice

Common wild rice(O.rufipogon) in the wild state with long-term survival competition and natural selection, has accumulated a mass of favorable genes and abundant genetic diversity. Utilizing exotic germplasm such as the wild rice is very important to broaden the genetic diversity of cultivated rice, and to break the genetic bottleneck in rice.Crop biosmass and yield is due to photosynthesis production.Chlorophyll content is an important factor for the photosynthetic efficiency. Up to date, few genes related to flag leaf SPAD-value in rice was identified, though many QTLs were reported by using segregant populations. In this research, the chromosome segment substitution lines(CSSL) derived from the cross of zhenshan 97B and a common wild rice from Malaysia were re-evaluated and developed. Previously, we found a QTL on chromosome 1 correlated with the chlorophyll content that were measured by flag leaf SPAD-value in the CSSL. So a F2 segregating population and its F3 family were constructed and used to validate the QTL for SPAD-value. The main results are as follows:1. The target segments each in 131 lines of CSSLs developed overlap the whole genome of wild rice with length of 362.6 Mb (about 1450.4 cM). All of substitution segments add up to 838.6 Mb,2.3 times length of entire genome. The average length of substitution segments is 8.14 Mb (32.6 cM) ranging from 0.55 Mb (2.2 cM) to 23.75Mb (95 cM). The genetic linkage map consists of 174 SSR markers, covering the whole genome.2. Inclusive composite interval mapping (ICIM) were used to identify QTLs in the CSSLs.19 QTLs were detected for five traits which contains heading date, plant height, SPAD value, panicle number per plant and panicle length.3. By using a F2 segregating population, the SPAD-value QTL was validated which was found again in the CSSLs, and 96 F2 recombinants were filtered out to construct the F3 families. Mean value of each F3 family was used to reflect the phenotype of corresponding F2 plant for fine mapping. The result indicated that a QTL exists in the region of RM11954-RM11960 conferring flag leaf SPAD-value.