Identification Of QTLs Controlling Yield Traits And High Photosynthesis Efficiency Using Introgression Lines Of Common Wild Rice (O.rufipogon Griff) From Yuanjiang In Yunnan Province

Based on an advanced backcross population and a set of introgression lines were developed using repeat backcross between an accession of Oryza ruftpogon from Yuanjiang, Yunnan province in China, as the donor, and the elite Indica cultivar Teqing, as the recipient, heterotic loci for yield and yield component traits were detected using backcross F₁ population between introgression lines and Teqing and test cross F₁ population between introgression lines and Peiai 64S. At the same time, QTLs for photosynthesis effect were identified using BC3F3 and introgression lines at two locations. The main results were as follows:1. A total of 52 QTLs for 8 yield and yield component traits were detected in BC3F3 population and introgression lines. 15 QTLs were found in the two populations. QTLs (qGP8-l, qFG8-l, qYP8-l and qPN 8-1) for grain number per panicle, full grain number per panicle, yield per panicle and panicle per plant were detected near RM337 on chromosome 8 that explained 24% and 8%, 23% and 9%, 21% and 13%, 15% and 7% of the phenotypic variance in the two population respectively and which additive effects were 100.75 and 58.95, 62.00 and 58.07, 1.43 and 1.67, -2.75 and -2.41 respectively. The alleles from Yuanjiang common wild rice in those loci could increase grain number per panicle, full grain number per panicle, yield per panicle and decrease panicle per plant of Teqing.2. One heterotic locus for grain number per panicle and grain yield per panicle that explained 13% and 10% of phenotypic variance respectively was found near SSR marker RM3 on chromosome 6 using backcross F₁ phenotypic values and mid-parent heterosis values (H_mp). For the QTL, the heterozygote enhanced grain number per panicle and grain yield per panicle, when compared with the homozygote. And at single locus level, the genetic effect of the heterosis locus showed overdominance.3. One major QTL controlling yield and yield component traits except yield per plant and seed set ratio was identified near RM298 on chromosome 7 that explained average 17% of phenotypic variance using test cross F₁ population. The result that additive effect of QTL for panicles per plant was positive showed that the allele from Yuanjiang common wild rice could increase panicles per plant of Teqing.4. A total 61 heterotic loci for yield and yield component traits were detected using mid-parent heterosis values for backcross population. The heterozygote of 32 loci showed positive heterosis and of 28 loci showed negative. Using analysis of the genetic effect of heterotic loci, the results showed that the heterotic effect of 4 loci was dominance and of 56 loci (about 93.3%) was overdominance. The result suggested that overdomiance effect was the main genetic basis of heterosis at single locus level.5. Three QTLs for photosynthesis effect were found near SSR marker RM153 on chromosome 5 (qNPR5.1), RM105 on chromosome 9 (qNPR9.1) and RM453 on chromosome 12 (qNPR12.1) respectively. The alleles from Yuanjiang common wild rice in those loci could enhance net photosynthesis ratio of the populations. qNPR5.1 was detected in the two populations , that could explained 7% and 6% of phenotypic variance and which additive effect was 5.94 and 3.79 respectively.