小麦幼苗根系性状的QTL分析

Mapping QTL for Seedling Root Traits in Common Wheat

以小麦DH群体(旱选10号×鲁麦14)为材料,在水分胁迫及非胁迫两种条件下考察水培幼苗的单株根数、最大根长、根鲜重、根干重、根茎鲜重比及根茎干重比等根系性状。应用基于混合线性模型的复合区间作图法分析幼苗根系性状的QTL,以及基因与环境的互作。共检测到11个加性效应QTL和15对上位性互作QTL,分布在除5A、4B、2D、6D和7D以外的所有染色体上。其中3个加性效应QTL和2对上位性效应QTL控制根数;3个加性效应QTL和3对上位性效应QTL控制最大根长;2个加性效应QTL和2对上位性效应QTL控制根鲜重;2个加性效应QTL和3对上位性效应QTL影响根干重;2对上位性效应QTL控制根茎鲜重比;1个加性效应QTL和3对上位性效应QTL与根茎干重比有关。同时还分别检测到1个加性效应QTL、3对上位性效应QTL与水分环境的互作效应。对应用分子标记辅助选择幼苗抗旱优良根系性状的可能性进行了讨论。

A doubled haploid （DH） population with 150 lines, derived from a cross between two common wheat varieties Hanxuan10 and Lumai14, was used in this research. Several root traits including root number （RN）, maximum root length （MRL）, root fresh weight （RFW）, root dry weight （RDW）, ratio of root fresh weight to shoot fresh weight （RFW/SFW） and ratio of root dry weight to shoot dry weight （RDW/SDW）per plant of hydroponic seedlings were measured under water stress and control conditions, respectively. Quantitative trait loci （QTL） and GxE interactions for these traits were detected using mixed-model-based composite interval mapping method. A total of 11 additive QTL and 15 pairs of epistatic QTL associated with root traits were mapped on all chromosomes except 5A, 4B, 2D, 6D and 7D. Among these QTL, 3 QTL with additive effects and 2 pairs of epistatic QTL controlling root number, 3 QTL with additive effects and 3 pairs of epistatic QTL controlling maximum root length, 2 QTL with additive effects and 2 pairs of epistatic QTL controlling root fresh weight, 2 QTL with additive effects and 3 pairs of epistatic QTL controlling root dry weight, 2 pairs of epistatic QTL controlling ratio of root fresh weight to shoot fresh weight and 1 QTL with additive effects and 3 pairs of epistatic QTL controlling ratio of root dry weight to shoot dry weight were detected. One additive QTL × environment and three pairs of epistatic QTL × environment interaction effects were also identified. The possibility of using marker-assisted selecting root traits and drought tolerance in wheat was discussed.