Fine Mapping Of QPR10-main Photosynthetic Rate QTL Of Rice (Oryza Sativa L.) And Its Transcriptome Analysis

Photosynthesis is a physiological metabolism of great importance in Rice,and also has extremely significant effect on yield. Rice is one of the major food crops in China, even in Southeast Asia. Facing the serious food shortage under current world, it’s urgently need to launch rice photosynthesis rate project of imminent. Research Progress on rice photosynthetic genes growing so slow, mainly due to the determination of Pn is too hard,by the index of environment impact, and it is a quantitative trait controlled by multiple genes and uneasy to explain with the complex traits. At the present stage, relevant report of rice photosynthetic QTL contains a large numbers of preliminary mapping of characters associated with photosynthesis, there are few fine mapping QTL.This study was based on a preliminary mapping, using the recombinant inbred lines from a cross between Zhenshan 97B(indica) and IRAT109(japonica) to rebuild a new population. Multiple backcross with parent Zhenshan 97 B and molecular marker assisted selection, we construct a population of chromosome segment substitution lines, carrying the break-in target segment of chromosome 10 derived from IRAT109. With the population,we analysis fine mapping within the target section of the photosynthetic QTL and function of significant differential gene expression of transcriptome.The conclusions of this study are as follows:1Design new molecular markers in the target fragments of chr10, adding 8 InDel molecular markers in the original target section RM596-RM271,the physical distance between markers is reduced to 200 KB, constructed the QTL molecular marker map of fine mapping.2 In the population of NIL, using molecular marker assisted selection, we complete selection of target fragments in different exchange recombinant homozygous plants. After investigation of photosynthesis and heading stage, we found that there is one heading date gene EHD1, reported in the early study, located near the target section. By effects of heading date, the difficulty for groups of light QTL mapping accuracy increased. The gene is derived from IRAT109,which heading date is delaied, the female homozygous fragment plant heading stage were advanced, and the male homozygous plants heading stage is relatively late, the chain of traits and locus interfere the phenotype detection. Analysis the phenotype with genotype, we assume there is a correlation between 200 KB fragment in GH16-GH18 and photosynthesis.3.We using L1, L2, L3,DK1 and DK3 for transcriptome analysis divide into 2 groups. 5 samples come from BC4F1 population,with the treatment of light and dark. Data show that, in the target range, under the comparison of two treatments, there are 4 genes show significant differential gene expression : LOC_Os10g30162.1 encodes Starch synthase II or chloroplast precursor; LOC_Os10g30156.1 encodes Heat shock protein Hsp20 domain containing protein; LOC_Os10g31320.1 encodes UDP-glucoronosyl and UDP-glucosyl transferase family protein; LOC_Os10g30560.1 encodes a hypothetical protein. Carrying the IRAT109 fragment, Starch synthase II, chloroplast precursor and Heat shock protein Hsp20 domain containing protein gene expression are significantly lower in L1, L2 and DK1,whereas UDP-glucoronosyl and UDP-glucosyl transferase family protein gene expression is improved significantly.4. Transcriptome gene function analysis of differential gene expression show that with target fragment,highly expressed differential gene show up in Light harvesting chlorophyll protein complex and plant Circadian rhythm pathways related with photosynthesis.