Lowry David B, Hernandez Kyle, Taylor Samuel H, Meyer Eli, Logan Tierney L, Barry Kerrie W, Chapman Jarrod A, Rokhsar Daniel S, Schmutz Jeremy, Juenger Thomas E
Department of Integrative Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station C0990, Austin, TX, 78712, USA; Division of Science and Environmental Policy, California State University, Monterey Bay, 100 Campus Center, Seaside, CA, 93955, USA.
New Phytol. 2015 Jan;205(1):402-14. doi: 10.1111/nph.13027. Epub 2014 Sep 23.
The process of plant speciation often involves the evolution of divergent ecotypes in response to differences in soil water availability between habitats. While the same set of traits is frequently associated with xeric/mesic ecotype divergence, it is unknown whether those traits evolve independently or if they evolve in tandem as a result of genetic colocalization either by pleiotropy or genetic linkage. The self-fertilizing C4 grass species Panicum hallii includes two major ecotypes found in xeric (var. hallii) or mesic (var. filipes) habitats. We constructed the first linkage map for P. hallii by genotyping a reduced representation genomic library of an F2 population derived from an intercross of var. hallii and filipes. We then evaluated the genetic architecture of divergence between these ecotypes through quantitative trait locus (QTL) mapping. Overall, we mapped QTLs for nine morphological traits that are involved in the divergence between the ecotypes. QTLs for five key ecotype-differentiating traits all colocalized to the same region of linkage group five. Leaf physiological traits were less divergent between ecotypes, but we still mapped five physiological QTLs. We also discovered a two-locus Dobzhansky-Muller hybrid incompatibility. Our study suggests that ecotype-differentiating traits may evolve in tandem as a result of genetic colocalization.
植物物种形成过程通常涉及不同生态型的进化，以响应不同生境间土壤水分可利用性的差异。虽然同一组性状常与旱生/中生生态型分化相关，但尚不清楚这些性状是独立进化，还是由于基因共定位（通过基因多效性或遗传连锁）而协同进化。自花授粉的C4禾本科物种哈利稗（Panicum hallii）包括在旱生（哈利稗变种）或中生（细柄稗变种）生境中发现的两种主要生态型。我们通过对来自哈利稗变种和细柄稗变种杂交的F2群体的简化基因组文库进行基因分型，构建了哈利稗的首张连锁图谱。然后，我们通过数量性状位点（QTL）定位评估了这些生态型之间分化的遗传结构。总体而言，我们定位了与生态型间分化相关的9个形态性状的QTL。5个关键生态型分化性状的QTL均共定位于连锁群5的同一区域。生态型之间叶片生理性状的差异较小，但我们仍定位了5个生理QTL。我们还发现了一个双位点的杜布赞斯基-穆勒杂种不亲和性。我们的研究表明，生态型分化性状可能由于基因共定位而协同进化。
