Stansell Zachary, Farnham Mark, Björkman Thomas
School of Integrative Plant Science, Cornell University, Ithaca, NY, United States.
Cornell Agritech, Cornell University, Geneva, NY, United States.
Front Plant Sci. 2019 Sep 18;10:1104. doi: 10.3389/fpls.2019.01104. eCollection 2019.
Improving horticultural quality in regionally adapted broccoli ( var. ) and other crops is challenging due to complex genetic control of traits affecting morphology, development, and yield. Mapping horticultural quality traits to genomic loci is an essential step in these improvement efforts. Understanding the mechanisms underlying horticultural quality enables multi-trait marker-assisted selection for improved, resilient, and regionally adapted germplasm. The publicly-available biparental double-haploid BolTBDH mapping population (Chinese kale × broccoli; = 175) was evaluated for 25 horticultural traits in six trait classes (architecture, biomass, phenology, leaf morphology, floral morphology, and head quality) by multiple quantitative trait loci mapping using 1,881 genotype-by-sequencing derived single nucleotide polymorphisms. The physical locations of 56 single and 41 epistatic quantitative trait locus (QTL) were identified. Four head quality QTL (OQ_C03@57.0, OQ_C04@33.3, OQ_CC08@25.5, and OQ_C09@49.7) explain a cumulative 81.9% of phenotypic variance in the broccoli heading phenotype, contain the () homologs Bo9g173400 and Bo9g173370, and exhibit epistatic effects. Three key genomic hotspots associated with pleiotropic control of the broccoli heading phenotype were identified. One phenology hotspot reduces days to flowering by 7.0 days and includes an additional homolog Bo3g024250 that does not exhibit epistatic effects with the three horticultural quality hotspots. Strong candidates for other horticultural traits were identified: (Bo3g002560) associated with serrated leaf margins and leaf apex shape, (Bo3g158650) implicated in flower color, and (Bo1g004960) implicated in the hooked sepal horticultural trait. The BolTBDH population provides a framework for improvement by targeting key genomic loci contributing to high horticultural quality broccoli and enabling mapping of currently unexplored traits.
由于影响形态、发育和产量的性状受到复杂的基因控制，提高区域适应性西兰花（变种）和其他作物的园艺品质具有挑战性。将园艺品质性状定位到基因组位点是这些改良工作的关键一步。了解园艺品质的潜在机制有助于进行多性状标记辅助选择，以培育出改良的、适应性强的和适合区域种植的种质资源。利用1881个通过测序获得的单核苷酸多态性，通过多数量性状基因座定位，对公开可用的双亲双单倍体BolTBDH作图群体（芥蓝×西兰花；n = 175）的六个性状类别（株型、生物量、物候、叶片形态、花形态和花球品质）中的25个园艺性状进行了评估。确定了56个单基因和41个上位性数量性状基因座（QTL）的物理位置。四个花球品质QTL（OQ_C03@57.0、OQ_C04@33.3、OQ_CC08@25.5和OQ_C09@49.7）解释了西兰花结球表型中81.9%的表型变异，包含（）同源基因Bo9g173400和Bo9g173370，并表现出上位性效应。确定了与西兰花结球表型的多效性控制相关的三个关键基因组热点区域。一个物候热点区域使开花天数减少7.0天，并且包含另一个同源基因Bo3g024250，该基因与三个园艺品质热点区域不表现上位性效应。还确定了其他园艺性状的有力候选基因：与锯齿状叶缘和叶尖形状相关的（Bo3g002560）、与花色有关的（Bo3g158650）以及与钩状萼片园艺性状有关的（Bo1g004960）基因。BolTBDH群体为通过靶向有助于培育高品质园艺西兰花的关键基因组位点以及实现对目前尚未探索的性状进行定位，从而改良西兰花提供了一个框架。
