Conditional QTL Analysis Of Grain Protein Content In Wheat

QTL mapping for developmental behavior of GPC was studied using a 168-line doubled haploid(DH) population derived from two elite Chinese wheat cultivars Huapei3 and Yumai57. The accumulation law of GPC was studied and QTLs/genes expressed at five seed filling were detected to attain more genetic information of GPC. The effect of irrigation conditions on GPC at mature season was also studied using this DH population, and QTL mapping will reveal the genetic mechanism of GPC affected by different irrigation conditions. The results were summarized as follows:1. Based on the genetic map established from the DH population, the dynamic development of GPC were studied in 6 environments.The results showed that:the dynamic change of GPC showed a "high - low - high" tendency in the seed filling process and attained"low valley"at 22 d after anthesis. The GPC of the DH population segregated continuously, and both absolute values of skewness and kurtosis were less than 1.0, indicating its polygenic inheritance and suit-ability of the data for QTL analysis.2. A total of 9 unconditional additive QTLs distributing on the chromosomes 1D, 2B, 3A, 4A, 4B, 5A, 5D and 7D were detected at five seed filling stages. QGpc3A which persistently expressed at all seed filling stages could highest account for 14.79% of phenotypic variation as a major QTL.QGpc4A-1, QGpc4A-2 and QGpc1D which persistently expressed at 2 or 3 stages could also play important role for the accumulation of GPC,the rest unconditional QTLs could be only detected at a special period. A total of 11 conditional additive QTLs distributing on the chromosomes 1D, 2B, 3A, 4A, 4B, 4D, 5B, 5D and 7D were detected. QGpc3A could be detected at two seed filling stages, the rest conditional QTLs could be only detected at a special period.3. A total of 8 unconditional estimated epistasis QTLs were detected at five seed filling stages which could account for 7.5%(12 d after anthesis), 2.47%(17 d after anthesis), 4.81%(22 d after anthesis), 11.76%(27 d after anthesis) and 9.46%(32 d after anthesis) of phenotypic variation respectively. QGpc3A/QGpc7A-1 could be detected at two seed filling stages (12 d after anthesis and 27 d after anthesis), the rest unconditional estimated epistasis QTLs could be only detected at a special period. A total of 7 conditional estimated epistasis QTLs distributing were detected which could account for 7.5%(12 d after anthesis), 13.77%(17 d after anthesis), 9.32%(22 d after anthesis) and 4.17%(32 d after anthesis) of phenotypic variation respectively. All the conditional estimated epistasis QTLs could be only detected at a special period.4. Based on the genetic map established from the DH population, GPC at mature season was studied in 6 irrigation conditions.The results showed that: Accumulation of GPC tended to be less under severe soil moisture deficit or over plentiful moisture conditions. No significant difference between the treatments with same irrigation times and different irrigation periods could be found owning to the widely separated type of the DH population.5. A total of 10 additive QTLs were detected in 6 irrigation conditions. QGpc3A which persistently expressed in all irrigation conditions could highest account for 10.81%(T1) of phenotypic variation as a major QTL. Gpc4D and QGpc3D could be detected in 4 and 3 irrigation conditions respectively, which could be detected QTL×environment effect at least in one environment. QGpc7D, QGpc2A, QGpc2D, QGpc1D, QGpc2D-1, QGpc5A and QGpc5B could be only detected at a special period.6. A total of 8 estimated epistasis QTLs were detected in 6 irrigation conditions. QGpc2B-3 /QGpc7A-2and QGpc2A-3/QGpc3B be detected in 3 and 2 irrigation conditions respectively, the rest estimated epistasis QTLs could be only detected at a special period.