Meta-analysis For Some Important Traits And QTL Analysis For Photosynthesis And Waterlogging Tolerance In Wheat

Most important traits of wheat, such as earliness, plant height, grain yield, quality, biotic stress and abiotic stress tolerance are generally reflecting quantitative inheritance. With the development of molecular biology, QTL location, isolation and MAS (molecular marker-assisted selection) are playing a much important role in crop genetic improvement on yield, quality and stress resistance. In this study, QTLs on plant height, garin yield, quality, Fusarium head blight, pre-harvesting sprouting and seed dormancy were collected for meta-anlysis. Meanwhile, QTL analysis for photosynthesis, agronomic traits and waterlogging tolerance were performed. The results were described as follows:1. QTLs on plant height (PH) and Fusarium head blight (FHB) were investigated by QTL meta-analysis from fifty six experiments. Twenty seven PH meta-QTLs (MQTLs) and thirty FHB MQTLs were predicted by mete-analysis. Coincident MQTLs for PH and FHB were found on chromosomes 2D,3A,4B,4D and 7A. Rht-Bl, Rht-DI, Rht8, MQTLs P7 and P26 were consistent with FHB MQTLs. The meta-analysis results confirmed the negative associations of Rht-Bl, Rht-Dl, and Rht8 with FHB resistance. The associations of PH and FHB resistance on chromosomes 3A and 7A have not been reported and need further investigation. These regions should be given attention in breeding programs. MQTLs derived from several resistance sources were also observed. Some FHB MQTLs for different types of resistance overlapped. These findings could be useful for improving wheat varieties with resistance to FHB.2. QTL meta-analysis was performed on pre-harvest sprouting (PHS) and seed dormancy (SD) from twenty six experiments. Nine major MQTLs (R2>10%) were located on 3A,3B,3D and 4A. Furthermore, the MQTL PHS2 on 3AS and four MQTLs on 4A, independent of red kernel colour loci could be used to develop PHS tolerant white wheat varieties. PHS and SD MQTLs were co-located in 49.45cM-49.74cM on chromosome 3B, and 69.35 cM-73.15 cM on 3D. The co-location confirmed that SD was the majore inheritant component of PHS. 3. Two hundred and ninety nine QTLs for grain yield, one hundred and fifty four QTLs for grain hardness and grain protein content (GPC) were meta-analysed. Twenty six MQTLs on grain yield and fourteen MQTLs on quality were deteced. The major MQTL, located at 55.58cM on 4A could explain 22.75%of phenotypic variance to grain yield. The co-located MQTLs, integrated at 21.67cM-28.47cM on 2DS, could explain 20.93%and 13.68%of phenotypic variance to grain yield and kernels per spike (KPS), respectively. All the genomic regions of 54.27cM-56.89cM on 4A,27.63cM-41.09cM on 4D and 33.46cM-43.09cM on 7DS were major regions for grain yield. One major MQTL was located on 5D and 1AS, individually, and the MQTL on 5D was consistent with Ha gene. The major MQTL, detected at 117.22cM on 6B, was a high GPC locus for protein content improvement, explaining 64.03%of GPC variance.4. The recombinant inbread lines (RILs), derived from the cross of Opata85 and W7984 were used for QTL analysis for phosynthesis associated traits. QTLs for chlorophyll content (Chl), net leaf photosynthetic rate (Pn), stomatal conductance (Cond), and internal CO2 concentration (Ci) at seedling stage, heading stage and grain filling stage were deteced. Wheareas, only a few QTLs were deteced at two different growth stages, non-comment QTLs were deteced at all three stages. Four stable QTLs for Chl were located on 3A,4D and 6A. Among them, the QTL, detected at 102.3cM on 4D was a major QTL, with a R2>10%. On chromosome 3A, two major QTLs for Pn and Cond were found. Another major QTL for Cond were located at 82.9cM on 2A. Two major QTLs for grain yield and KPS were deteced on 2D, and major QTLs for PH and economic yield were located on 4D and 7B, individually. Episistas QTLs were detected for most of the photosynthesis related traits and agronomic traits. The effect of Episistas QTLxEnvirnoment was much more important than that of Additive QTLxEnvirnoment. Four regions on 1D,2D and 3A, associated with both photosynthesis and grain yield were observed, which might be uself for developing wheat varieties with high or super high yield.5. Two sets of RILs were used for QTL analysis on waterlogging tolerance at germination and seedling stages. Six resistance QTLs at germination stage were deteced. The major QTL, located at 57.9cM on 7A could explain 23.92%of tolerance variance at germination stage. Twenty eight QTLs, located on sixteen chromosomes were observed in ITMI population. In the RILs, derived from SHW-L1 xSW8188,11 QTLs were deteced on 1A, 1B,5D,6A and 7D. None of episistas QTLs were deteced in either population, which indicated that waterlogging tolerance was controlled mainly by additive QTLs. Only a few of QTLs on growth and germination ability were observed both in stress and normal conditions. Co-located regions for different waterlogging tolerancecoefficient (WTC) were found in the study. One of the regions at 289.4cM on 7D, associated with WTC for Chl, root length and PH, accounted for more than 30% waterlogging tolerance at seedling stage. For the QTL, allele from SW8188 contributed for an increase of the tolerance.