利用“永久F2”群体进行小麦幼苗根系性状QTL分析

Identification of quantitative trait loci (QTLs) of roots plays an important role in the genetic mechanism study of root system. A number of QTLs for root traits have been detected using different populations in rice (Oryza sativa L.), but rarely in wheat (Triticum aestivum L.). The ”immortalized F2” population is favorable for QTL analysis due to its similar proportions of genotypes in the population, and the replicability at multiple locations over several years. The objective of this study was to detect QTLs for several root traits at seedling stage in wheat. From a set of doubled haploid lines derived from Huapei 3×Yumai 57, an ”immortalized F2” population was constructed with 168 single crosses. Wheat seedlings were hydroponically cultured with Hoagland’s solution in a light incubator, and sampled when the fifth leaf emerged. Nine root traits including root total length, root surface area, root average diameter, root volume, root tips, maximum root length, shoot dry weight, root dry weight, and ratio of root dry weight to shoot dry weight per plant were measured using the WinRHIZO Root Analysis System. QTLs associated with the nine traits were detected using composite interval mapping (CIM) method. A total of seven additive QTLs and 12 pairs of epistatic QTLs were mapped on chromosomes 1A, 1D, 2A, 2B, 2D, 3A, 3B, 5D, 6D, and 7D. Additive, dominant and epistatic effects were observed across these QTLs, including the interactions between additive and additive, additive and dominance, dominance and additive, as well as dominance and dominance. The phenotypic variation explained by each QTL ranged from 0.01% to 11.91%. In the interval between XWMC41 and XBARC349.2 on chromosome 2D, a QTL for total root length and root dry weight was detected. Epistasis was of great importance in root growth and development at seedling stage in wheat. The results showed a complex mechanism on the genetics of root traits in wheat, and the eight root traits were significantly correlated with each other. In marker-assisted breeding practice, several root traits should be considered simultaneously for an integrated performance of roots with proper size and shape.