Conditional And Unconditional QTL Mapping For Biological Yield Related Traits In Wheat (Triticum Aestivum L.)

Wheat is one of the main sources of human’s foodstuff and the most widely grown cereal ofthe world. With decrease of cropland and increase of population, food problem is becomingmore and more severe and increasing the potential yield could never be overstated. The grainyield of wheat can be broken down into two factors: harvest index and biological production.Over the past few decades, plant height of wheat varieties constantly reduce while harvestindex increases at the same time, but the biological yield remained relatively stable and littlechanged. Now the harvest index of wheat has reached40%~50%generally and close to themaximum. In order to promote further crop production, it is necessary to increase thebiological yield of wheat while keep in the harvest index level. In this research, a168-linedoubled haploid(DH) population derived from two wheat cultivars Huapei3and Ymai57, a256-line recombinant inbred lines(RIL) population derived from two wheat cultivars Nuomai1and Gaocheng8901, and a182-line recombinant inbred lines(RIL) population derived fromtwo wheat cultivars Shannong01-35and Gaocheng9411, are used to mapping QTLs for20traits related to biological yield in wheat. The main results were as follows:1. There were11additive QTL loci and12epistatic QTL loci for biological yield atreturning green stage, biological yield at jointing stage, biological yield of anthesis andbiological yield of maturity detected, and no major QTL was located on the chromosome.2. A total of26additive QTL loci and18epistatic QTL loci for the number of ears per plant,stalk weight per plant at anthesis stage, panicle weight per plant at maturity stage, stalkweight per plant at maturity stage, rachis and glumes weight per plant at maturity stage andyield per plant were detected. Most of these QTL loci have interaction with environments, andtheir effects are low.3. Uconditional and conditional mapping methods were applied in the analysis of geneticrelationship between biological yield of different parts at anthesis and biological yield of different parts at maturity.48unconditional additive QTL,15conditional additive QTL,25unconditional epistatic QTL and9conditional epistatic QTL were detected. There are manymajor QTL that have the contribution over10%. The QTL of Qspwa5A located on the5Achromosome of DH population could account for16.27%phenotypic variation of singlepanicle weight at anthesis stage; the QTL of Qstwa1B on the1B chromosome of RIL1population could account for15.07%phenotypic variation of single panicle weight at anthesisstage. The QTL loci locate on the maker interval of WPT-7569-WPT-3908on4Bchromosome of RIL2could be found in many traits mapping results.4. A total of8additive QTL loci and9epistatic QTL loci for higher move ratio of dry stemmatter after anthesis and harvest index were detected in the3populations. All the17QTL locihave interaction with environment.5. The traits of single stalk weight, single panicle weight, grain weight of each ear havestrong heritability and stability and are not easily affected by environment.The trait of number of ears per plant showed inconsistency and instability, its character wasaffected by circumstance factors easily.