Department of Plant Sciences, University of California Davis, CA, USA.
Evol Appl. 2012 Dec;5(8):850-7. doi: 10.1111/j.1752-4571.2012.00263.x.
Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However, the effects of domestication on the evolution of root plasticity are essentially unknown. Using a split container approach, we examined the differences in root plasticity among three domestication levels of barley germplasm (wild, landrace, and cultivar) grown under different concentrations and distribution patterns of soil nutrients. Domestication level, nutrient concentration, and nutrient distribution interactively affected average root diameter; differential root allocation (within-plant plasticity) was greatest in wild barley (Hordeum spontaneum), especially under low nutrient levels. Correlations of within-plant root plasticity and plant size were most pronounced in modern cultivars under low-nutrient conditions. Barley plants invested more resources to root systems when grown in low-nutrient soils and allocated more roots to higher-nutrient locations. Root plasticity in barley is scale dependent and varies with domestication level. Although wild barley harbors a greater capacity for within-plant root plasticity than domesticated barley, cultivars exhibited the greatest capacity to translate within-plant plasticity into increased plant size.
根系可塑性是一种能够对选择压力做出响应的特性，它可以帮助植物在异质土壤中寻找养分。农业育种计划已经人为地选择了在相对同质的土壤条件下增加产量，这可能降低了像大麦（Hordeum vulgare）这样的作物植物的可塑性能力。然而，驯化对根系可塑性进化的影响在本质上是未知的。通过采用分室容器的方法，我们研究了在不同浓度和分布模式的土壤养分条件下，三种大麦种质（野生、地方品种和栽培品种）的根系可塑性之间的差异。驯化水平、养分浓度和养分分布相互作用影响平均根直径；在野生大麦（Hordeum spontaneum）中，特别是在低养分水平下，根系分配的差异（植株内可塑性）最大。在低养分条件下，现代品种中植株内根系可塑性与植株大小的相关性最为显著。当在低养分土壤中生长时，大麦植物会向根系系统投入更多的资源，并将更多的根分配到养分较高的位置。大麦的根系可塑性具有尺度依赖性，并随驯化水平而变化。尽管野生大麦比驯化大麦具有更大的植株内根系可塑性，但品种表现出将植株内可塑性转化为增加植株大小的最大能力。
