QTL Mapping And Meta-analysis Of Related Traits To Accumulation And Remobilization Of WSC Of Different Organs In Wheat After Flowering

Wheat yield formation not only depends on performances of photosynthetic assimilates, but also is tightly associated with the efficient remobilization and translocation of water soluble carbohydrates(WSC) of vegetative organs after anthesis to grains. Therefore, both dissecting genetic basis of accumulation and remobilization of WSC of different organs in wheat after flowering and discovering meta QTL(MQTL) and their closely linked molecular markers are of importance to advance the genetic improvement in wheat drought resistance. In this study, one hundred and seven F8-derived recombinant inbred lines(RIL) from a cross between two common wheat cultivars Longjian 19(drought tolerant cultivar) and Q9086(water-sensitive cultivar) was developed to identify quantitative trait locus(QTL) and to dissect the genetic bases of WSC content at the early anthesis stage(WSCf), at grain-filling stage(WSCg), at the mature stage(WSCm), WSC remobilization rate at the pre-anthesis(RRpr), WSC contribution rate at the pre-anthesis(CRpr), WSC accumulation rate at the post-anthesis(RAps), WSC remobilization rate at the post-anthesis(RRps),WSC contribution rate at the post-anthesis(CRps), and grain weight of main spike(SGW) under drought stress and well-watered conditions consistent over four environments. By integrating QTLs identified for WSC-related traits, the meta-analysis is performed. The results are as follows:1. Under different water conditions, the phenotypic values of WSC-related traits in RIL population were closed to Longjian 19, and were higher in drought conditions(DS) than well-watered conditions(WW) except SGW. The genetic diversity index ranged from 0.68 to 0.91. All tested traits of RIL population varied in the phenotypic values sensitively responsible for water environments and showed significantly transgressive segregation. The broadsense heritabilities(h2B)were lower and ranged from 0.33 to 0.68. There were positive correlations to different extents between WSC contents in different growth stages, whereas correlation coefficients under the DS(r = 0. 32 * ~ 0. 84 **) were higher than the WW(r = 0. 20 ~ 0. 84 **). Furthermore, WSC content at different growth stages are showed higher relational grades with SGW(γ = 0.7066 ~ 0.7796).2. A total of 91 additive QTLs(A-QTLs) and 143 pairs of epistatic QTLs(AA-Q TLs)were detected for WSC-related traits in wheat, distributed on all chromosomes. The Q TL expressions could up- and down-regulate phenotypic variations in WSC-related traits, accounting for phenotypic variations of 0.01-9.18% by A-QTLs and 0.01-12.15% by AA-QTLs,respectively. There were 82 A-QTL and 141 AA-QTL significantly interacted with water e nvironments. These loci showed up- and down-regulation to phenotypic variations in WSC-r elated traits, explaining phenotypic variations of 0.01-10.37% by A-QTL interactions with w ater environments and 0.01-9.24% by AA-QTL interactions with water environments, respect ively. Some A-QTLs, such as Xcfa2278-Xgwm55(2B),Xgwm55-Xbarc128(2B),Xwmc540-Xgw m566(3B),Xgwm314-Xqwm456(3D),Xwmc621-Xbarc107(6A),Xbarc79-Xgwm626(6B)and Xwmc139-Xbarc195(7A).were repeatedly detected in multi-environments. In addition, 12 A-QTL ho t-spot regions for WSC-related traits were also found in some specific intervals, e.g., Xwmc582-Xwmc719 on chromosome 1B, Xgwm132-Xbarc128 on 2B, Xwmc25-Xgwm261 on 2D,Xpsp3112-Xcfd6 on 3B, Xgwm314-Xgwm456 on 3D, Xwmc757-Xgwm397 on 4A, Xbarc163-Xbarc60 on 4B, Xgwm408-Xwmc75 on 5B, Xwmc113-Xgwm82 on 6D, Xmag3023-Xgw m260 on 7A, Xbarc182-Xbarc94 on 7B, and Xgwm635-Xgwm428 on 7D.3. To explore true and major QTLs, a total of 271 QTLs controlling WSC-related traits from different genetic populations in wheat were employed to establish consensus map and to perform Meta-analysis by the method of bioinformatics, depending on a high-density ge netic map as a reference map. Thirty one MQTLs were identified and mapped on chromoso mes 1A, 1B, 2A, 2B, 3A, 3B, 3D, 4B, 4D, 5B, 6B, 6D, 7A and7 D. Each chromosome ave ragely contained 2.2 MQTLs. Theses MQTLs was distributed in cluster on the specific inter vals of chromosomes. Among them, the marker intervals P32-Xgbx3076 on chromosome 1A,Xwmc489-Xgwm410 on 2B, Xwmc512-Xbarc314 on 3B, Xw6-Xbarc7 on 3D, Xfbb3-Xcdo669 on 4D, Xwmc430-P37 on 5B, abg75b-Xgwm276 a on 7A showed MQTL hotspots for WSC accumulation and remobilization in wheat. In this study, The minimum confidence int erval reached to 0.77 c M. The findings might provide theoretical basis for fine mapping and map cloning for WSC-related traits in wheat.