Department of Plant Sciences, University of California at Davis, Davis, California 95616, USA.
Plant Cell. 2013 Jun;25(6):1929-45. doi: 10.1105/tpc.113.112615. Epub 2013 Jun 7.
To understand how genetic architecture translates between phenotypic levels, we mapped the genetic architecture of growth and defense within the Arabidopsis thaliana Kas × Tsu recombinant inbred line population. We measured plant growth using traditional size measurements and size-corrected growth rates. This population contains genetic variation in both the nuclear and cytoplasmic genomes, allowing us to separate their contributions. The cytoplasmic genome regulated a significant variance in growth but not defense, which was due to cytonuclear epistasis. Furthermore, growth adhered to an infinitesimal model of genetic architecture, while defense metabolism was more of a moderate-effect model. We found a lack of concordance between quantitative trait loci (QTL) regulating defense and those regulating growth. Given the published evidence proving the link between glucosinolates and growth, this is likely a false negative result caused by the limited population size. This size limitation creates an inability to test the entire potential genetic landscape possible between these two parents. We uncovered a significant effect of glucosinolates on growth once we accounted for allelic differences in growth QTLs. Therefore, other growth QTLs can mask the effects of defense upon growth. Investigating direct links across phenotypic hierarchies is fraught with difficulty; we identify issues complicating this analysis.
为了理解遗传结构在表型水平上的转化方式，我们对拟南芥 Kas × Tsu 重组自交系群体中的生长和防御的遗传结构进行了作图。我们使用传统的大小测量和大小校正的生长率来测量植物的生长。该群体包含核基因组和细胞质基因组的遗传变异，使我们能够分离它们的贡献。细胞质基因组调节了生长的显著方差，但不调节防御，这归因于细胞质核互作。此外，生长符合遗传结构的无穷小模型，而防御代谢则是一个中度效应模型。我们发现调节防御的数量性状基因座（QTL）与调节生长的 QTL之间缺乏一致性。鉴于已发表的证据证明了硫代葡萄糖苷与生长之间的联系，这很可能是由于群体规模有限而导致的假阴性结果。这种规模限制使得无法测试这两个亲本之间可能存在的整个潜在遗传景观。一旦我们考虑到生长 QTL 中的等位基因差异，就会发现硫代葡萄糖苷对生长有显著影响。因此，其他生长 QTL 可以掩盖防御对生长的影响。跨表型层次直接调查关联充满了困难；我们确定了使这种分析复杂化的问题。
