Ecophysiology and genetic variation in domestication of Sphaeralcea and Shepherdia species for the Intermountain West.

摘要

Low-water landscaping is an essential tool for water conservation in the arid Intermountain West (IMW) for managing limited supplies and population-driven increased demand. The IMW harbors a large number of drought-tolerant native species that have potential for use in the low-water use landscape (LWL). However, many species are not available in the nursery trade due to their morphological confusion and establishment difficulty in the managed landscapes. The overall goal of this study is to elucidate morphological, ecophysiological, and genetic distinctions within two IMW native plant genera containing species with high urban low-water landscape potential.;For the first study, morphological and genetic variations among populations of four putative Sphaeralcea species were evaluated using canonical variate analysis (CVA) on the basis of morphological characteristics of their type specimens, and amplified fragment length polymorphisms (AFLP). The putative S. grossulariifolia was not significantly different morphologically and genetically from S. coccinea, similar to the relationship between S. munroana and S. parvifolia. The results in the Mantel's correlation tests suggest there are con-specific species due to isolation-by-distance within each composite group, and the putative S. munroana appeared to be an ecotype of S. parvifolia.;In the second study, environmental conditions, morphology, and AFLP genetic variations among populations of Shepherdia rotundifolia in its native habitats were evaluated. Environmental conditions in selected six populations varied among populations in terms of elevation, precipitation, temperature, relative light intensity (RLI), and soil properties. Leaf area, specific leaf area (SLA), and leaf trichome structure exhibited adaptive traits to shady environments as well as hot and dry summer and cold winter environments in its native habitats. The SLA was significantly correlated with RLI, soil organic matter, and potassium.;In the third study, interspecific hybrid S. rotundifolia x argentea was created to achieve the aesthetic quality of S. rotundifolia and wet soil tolerance of S. argentea. The hybrid was intermediate morphologically and genetically (AFLP) to its parents. Trichome structure and physiological responses in terms of diurnal stomatal conductance (gs), photosynthetic light response curve, midday photosynthesis assimilation (Pn), and midday quantum efficiency (PhiPS2) of the hybrid were also more similar to S. argentea than to S. rotundifolia. The physiological responses of the hybrid compared to its parents may suggest tolerance to regularly watered conditions.