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

这一建议的目的是通过研究植物根系结构和对土壤氮素(N)和水分的响应的基因型差异来阐明影响植物根系形态变异的因素。不育的野生和栽培生菜(Lactuca serriola和L.sativa)将提供一套不同的种质，以适应广泛的土壤水分和养分状况。将利用根系拓扑学方法和生长速率测量来研究根系结构和塑料对肥沃土壤微站点的响应的基因型差异。将使用根拓扑法、生长速率、植物水分平衡的测量(包括直接测量(气孔导度、叶水势)和间接测量(稳定碳同位素鉴别))以及稳定同位素15N的短期标记来研究从富集微站点中提取水、铵和硝酸盐的能力。更好地了解环境对根生长的影响，包括不同基因型之间的反应差异，将为改善栽培生菜的水分和氮素吸收提供基础，生菜是一种浅根作物，对肥料N和灌溉投入的需求很高。

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.