Genetic Analysis And QTL Mapping Of Waterlogging Tolerance At Seedling Stage In Barley

Waterlogging is one of the major restriction for barley production and quality, especially in the middle and lower region of the Changjiang River in our country. The growth of barley at seedling stage impacts on yield-building. Therefore, to understand genetic mechanisms of waterlogging tolerance at seedling stage, e.g.quantitative trait loci (QTL) location by the use of molecular markers, will provide bases for barley breeding, especially marker-assisted selection.This study was based on the identify barley germplam of waterlogging-tolerance.A population of DH was constructed by anther culture, which derived from a cross between Taixing9425with waterlogging tolerance and Franklin which is susceptible to waterlogging. Waterlogging treatments were carried at seedling stage (2009and2010). The differences of the influence of waterlogging and the the correlation were analysed based on the morphological characters and physiological characters, including seedling height (SH), yellow leaf number(YLN), tiller number(TN), leaf age (LA), chlorophyll content (CC), superoxide dismutase activity (SODA), malondialdehyde content (MDAC). In order to map QTL related to all traits, a molecular linkage map was built. Identifying the major effects QTL related to waterlogging tolerance by comparative analysis the difference in two years and two environments.(1) All traits were different between the parents under the control and treatment. Some characters were significantly difference. Waterlogging influenced significantly the plant traits and there were significant genetic differences among the DH lines. Transgressive segregations for all traits were observed in the population, and their frequencies were showed a continuous distribution. Waterlogging tolerance is controlled by multi-genes with major effects, and minor modifiers.(2)158QTL were detected for7traits associated with waterlogging tolerance under two years and two experiments.74QTL were detected under normal environment, and84QTL were detected under water stress environment. Each character have been identified1-8QTL which were responsible for interpreting6.56%-38.38%, and the range of LOD were2.48-7.92. Tightly linked QTL regions on chromosome2,3and5were identified, which suggested the existence of pleiotropic or genetic linkage.This was the key chromosome regions for characters associated with waterlogging tolerance.(3)59QTL of specific expressed were detected only under waterlogging by comparing the difference between QTL detected two environments.The alleles for30QTLs originated from the tolerant parent Taixing9425, and the alleles of other QTL were derived from waterlogging sensitive parent Franklin. The min contribution to phenotypic variance was8.82%and the max was36.46%.12QTL related to waterlogging tolerance were detected by yellow leaf number, and17QTL related to waterlogging tolerance were detected by chlorophyll content.(4)4stability of QTL associated with waterlogging tolerance were verified in different years or different stages in one year.These QTL were located in the chromosome3,4and5. qSH3-1value of seedling height was detected to the same mark interval of bPb-0079-bPb-6765. qYLN5-1value of yellow leaf number was detected near the marker p5b1. qCC4-1value of chlorophyll content was detected near the marker bPb-6523. qCC5-3value of chlorophyll content was detected to the mark interval of p9b7-bPb-0171.