Search Results
An Impatiens germplasm collection consisting of accessions (from Africa, New Guinea [NG[, Sri Lanka, and Java/Celebes, a NG breeding population, and selected interspecific hybrids was characterized for 32 morphological traits and two ensyme systems, peroxidase (PER) and aspartate amino transferase (AAT). Thirteen PER and three AAT isozymes were identified, and both enzyme systems appeared to be co-dominatly inherited. There were unique zymograms for the accessions and the interspecific hybrids, but not the NG breeding population.
A Generalized Fisher Exact Test indicated that qualitative characters of the accessions were independent of each other, of isozyme traits and of geographical origin of the accession; this was not true for isozymes. Principal component analysis combining both morphological and isozyme traits uniquely separated the accessions while also indicating clusters of similarity. Extensive genetic diversity was indicated for all traits in the accessions and for quantitative traits in the NG breeding population.
Intraspecific variation in nitrate absorption by turfgrasses has been studied, but differences in turfgrass root morphology, which may contribute to observed variation, have not been ascertained. This information may benefit breeding programs aimed at improving the ability of turfgrasses to absorb nitrate from low fertility soils. This study quantified root morphological traits of Kentucky bluegrass (Poa pratensis L.) cultivars and their nitrate uptake rates (NUR). Tiller-generated plants were grown in silica sand, mowed weekly, and watered daily with half-strength modified Hoagland's nutrient solution containing 1 mM nitrate. When 5 months old, plants were excavated, and roots washed to remove sand. The plants were then transferred to 120-mL black bottles. After nitrate depletion of the nutrient solution was monitored for 8 consecutive days, the underground portion of each plant was separated into three parts: 1) adventitious roots, 2) fibrous roots, and 3) rhizomes. Measurements of total root length, total surface area, and average diameter were made by a scanning and image analysis system. NURs were calculated from nitrate depletion data and expressed as micromoles per plant per hour. Correlation analyses were performed on these morphological traits and NUR by the Minitab program. NUR was significantly and positively correlated with the total biomass, length, and area of the three underground parts. This was attributable mainly to fibrous roots as indicated by significant and positive correlations between NUR and the total biomass, length, area, and average diameter of fibrous roots. NUR was also positively correlated with the total biomass, length, and area of adventitious roots but negatively correlated with total biomass, area, and average diameter of rhizomes.
As one of the Florida's state wildflowers, Coreopsis leavenworthii is highly desirable for roadside plantings in all parts of the state. Seeds of this species are being produced by growers. Where should seed be produced for different ecotypes? Where can the seed be used? These are among questions that have arisen in commercial seed production and distribution. To address these questions, it was necessary to assess the levels of genetic diversity. Eleven populations (242 total individuals) were collected from different parts of Florida, grown at one location in central Florida, and observed for morphological variations. North Florida natural populations had more complex leaves, while south Florida natural populations had smaller flowers. Principal component analyses revealed that two of the seven characteristics studied accounted for as much as 88% of the morphological variations observed. Molecular diversity was analyzed by using the fluorescent amplified fragment length polymorphism (AFLP) technique and the capillary sequencing system. Four primer combinations detected 320 AFLP fragments, of which 90.6% were polymorphic. The overall genetic diversity in the species was 0.2206 (estimated using AMOVA), of which 77.9% was within populations and 22.1% was among populations. The genetic distance among populations seemed to be loosely correlated with geographical distances. A high level of gene flow was found in several populations. Based on the results, a model has been developed to describe the genetic relationship of Coreopsis leavenworthii populations.
Sorbitol is the predominant phloem-translocated carbohydrate in apple. The pathway—either apoplastic or symplastic—of sugar transport from photosynthetic cells to the phloem is not established. Furthermore, the presence of absence of phloem loading has not been tested. This study characterized the morphology and physiology of sugar movement to the phloem in apple leaves. An electron micrographic survey of apple leaf minor vein morphology was performed. Plasmodesmata were abundant and found at the interfaces of each cell type from mesophyll to sieve elements, indicating a symplastic sugar pathway. We also tested for a phloem loading mechanism. First, 14C-labeled sorbitol and sucrose were introduced exogenously to leaf discs to determine if they are loaded into veins from the apoplast. Although leaf discs floated on a solution containing either sugar actively accumulated label, the labeling pattern was diffuse, with no accumulation in minor veins. The addition of the sulfhydryl reagent PCMBS to the leaf disc assay inhibited sugar uptake. We also attempted plasmolysis of apple leaf sections to measure the solute concentration difference between photosynthetic mesophyll cells and cells of the minor vein phloem. Apple leaf pieces fixed in a solution containing 1.5 mol/kg osmoticum did not plasmolyze. We conclude that although active uptake of both sorbitol and sucrose takes place in apple leaves, apoplastic phloem-loading is absent. Considering the high sugar concentration and the symplastic connectivity among leaf cell types, we propose that sugars are instead enter the phloem after moving down—rather than against—a concentration gradient.
propagation and production are not clear. The narrow spectra of supplemental LED lighting have potential implications on morphology, development, and gas exchange of plants. First, although all photons between 400 and 700 nm (photosynthetically active
interaction between LI and LQ on the growth and nutrient content of Brassica microgreens. Therefore, the objective of this study was to quantify the effects of SS LEDs providing different LIs and LQs on the growth, morphology, and nutrient content of
The stone cells events in the process of lignifications of plant tissues in flesh of Asian pear have been growing as a depressing factor of fruit quality. Therefore, these studies were carried out to search the effect of stone cells on fruit quality, to investigate the anatomical characteristics, such as formative period and distribution of stone cell, to seek forming causes, and to determine the effects of drought stress and calcium foliar application on the formation of stone cell. Fruit quality as contents of the stone cells, such as texture profile, reducing sugars, firmness, and fruit size, were determined. During the growing season of 2002 and 2003, samples for anatomical investigations were taken periodically in Pyrus pyriforia cv. Niitaka, Pyrus communis cv. Bartlett and Pyrus ussiriansis cv. Yari. The morphology of stone cell in the fruit flesh was observed by using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM).
The rare plant, Fragaria multicipita Fern., was characterized by an unusual vegetative morphology that was long presumed to be suggestive of an ice front relict. While an additional species of Fragaria would be a potential source of genetic diversity for enhancing cultivated strawberry germplasm, evidence now indicates that such potential is not present in F. multicipita. Grafting of F. multicipita to F. chiloensis Duchesne resulted in transmission of a subgroup 16SrVI-B phytoplasma to, and the development of multicipital growth in, F. chiloensis. The results indicated that F. multicipita is a phytoplasma-diseased aberrant growth form of F. virginiana Duchesne and is an unfounded taxon. It is apparent that this plant population offers no unique potential for increasing genetic diversity in cultivated strawberry germplasm, but the phytoplasma may be capable of infecting commercial strawberry.
The morphology of interspecific Exacum hybrids was investigated in order to determine transmission patterns of several horticultural traits and to confirm interspecific hybrid status of plants. The evaluations utilized 557 accessions from interspecific hybridization of the following species: Exacum. macranthum, E. pallidum, E. pedunculatum, E. trinervium ssp. ritigalensis, and E. trinervium ssp. trinervium. Transmission patterns are proposed for stem shape (three phenotypes- clylindrical, winged-cylindrical and qudrangular; no dominance), petal shape (two phenotypes-rounded and acuminate; rounded dominant to acuminate) and flower form (two phenotypes- imbricate and separate; imbricate dominant to separate) Examination of the progenies confirm interspecific hybridization by the appearance of combinations of traits from the parental species and/or the observation of unique forms not previously observed.
Recently, turfgrass breeders have developed many improved turf-type tall fescue (Festuca arundinacea Schreb.) cultivars. Due to the large number of cultivars currently available to turfgrass managers and researchers, we have classified turf-type tall fescue cultivars into six groups based primarily on several morphological measurements. This type of classification is important for turfgrass breeders because many breeding decisions are made based on observations in a spaced-plant nursery. The major objective of this study was to classify tall fescue cultivars and selections based on spaced-plant measurements and to then compare those results with turf performance. A spaced-plant nursery consisting of 36 cultivars and selections was established in September 1998 at Adelphia, N.J. Plant height, panicle length, flag leaf width and length, subtending leaf width and length, and subtending internode length were measured 10 days after anthesis in 1999 and 2000. Additionally, a turf trial was established at North Brunswick, N.J., that included the same 36 cultivars and selections. The turf plots were evaluated for several traits including overall turfgrass quality, density, and susceptibility to brown patch disease. Based on principal component analysis of morphological measurements, along with turf trial data, all cultivars and selections were assigned to one of six groups: forage, early-standard, standard, early semi-dwarf, semi-dwarf, and dwarf. In turf plots, the semi-dwarf, early-semi dwarf, and dwarf groups were the top-performing types in terms of overall turfgrass quality, and the forage and early-standard cultivars had the lowest overall quality ratings. The dwarf types did not perform well under summer stress, especially in terms of brown patch disease incidence. The results of this study suggest that when developing cultivars for higher maintenance situations, turf-type tall fescue breeders should focus on the development of semi-dwarf cultivars.