Environmental and Genetic Effects on Root Structure in Wild and Cultivated Lettuce (Lactuca spp.)

本研究的目的是通过研究根系结构的基因型差异以及对土壤氮和水分的响应，阐明影响植物根系形态变化的因素。无性野生和栽培莴苣（lacuca serriola和L. sativa）将提供一套适应各种土壤水分和养分制度的不同种质资源。根系结构的基因型差异和对土壤微站点的可塑性响应将通过根系拓扑方法和生长速率测量进行研究。研究人员将利用根系拓扑方法、生长速率、植物水分平衡测量(包括直接测量（气孔导度、叶片水势）和间接测量（稳定碳同位素判别），以及稳定同位素15N的短期标记来研究从富集微位点提取水分、铵态氮和硝酸盐的能力。更好地了解环境对根系生长的影响，包括基因型之间的响应差异，将为改善栽培莴苣的水分和氮吸收提供基础，生菜是一种对肥料氮和灌溉投入需求高的浅根作物。

The objective of this proposal is to clarify factors influencing morphological variation in plant roots by examining genotypic differences in root system structure and responses to soil nitrogen (N) and water. The infertile wild and cultivated accessions of lettuce (Lactuca serriola and L. sativa) will provide a devierse set of germplasm adapted to a wide range of soil water and nutrient regimes. Genotypic differences in root system structure and plastic responses to enriched soil microsites will be studied using root topological methods and growth rate measurements. Ability to extract water, ammonium, and nitrate from enriched microsites will be studied using the root topological method, growth rates, measurements of plant water balance including both direct (stomatal conductance, leaf water potential) and indirect measurements (stable carbon isotope discrimination), and short-term labeling with the stable isotope, 15N. Improved understanding of environmental effects on root growth, including differences in response among genotypes, will provide a basis for improving water and N absorption of cultivated lettuce, a shallow-rooted crop with high demand for fertilizer N and irrigation inputs.