Genome Size and Chromosome Analyses in Prairie Cordgrass

Abstract

The next generation of bioenergy crops will be grown on marginal lands. Prairie cordgrass (Spartina pectinata Link) is well suited to marginal land because of its tolerance to stresses such as salinity and water fluctuations. Developing prairie cordgrass as an energy crop requires genomic information such as genomic size and ploidy level. The 2C nuclear genome size of 11 prairie cordgrass populations, originating from Illinois, North Dakota, and South Dakota, were determined by flow cytometry using somatic G1 nuclei, and the ploidy variation confirmed by counting the chromosome number. One population from each of North Dakota and South Dakota, as well as the Red River, had genome sizes of 3.1 pg of DNA per G1 somatic nucleus whereas, the majority of the eight populations from Illinois had a genome size of 1.6 pg. One plant from one of the Illinois populations had an estimated genome size of 2.3 pg. These genome sizes of 3.1 and 1.6 pg, along with their respective chromosome numbers of 80 and 40 indicate octoploid and tetraploid plants. The chromosome number of 60 observed in the plant with 2.3 pg indicated that this plant was hexaploid. This study provides the first estimates of genome size for prairie cordgrass and is also the first to report observed hexaploidy in this species. This genomic information provides critical knowledge for designing efficient breeding schemes for plant improvement.

Using satellite vegetation and compound topographic indices to map highly erodible cropland buffers for cellulosic biofuel crop developments in eastern Nebraska, USA

“…Advantages of converting agricultural lands to perennial grass biofuel feedstocks in the riparian buffers and high topographic relief areas include: (1) filtering of surface-water flows, reducing export of cropland nitrogen, and improving water quality because switchgrass requires less fertilizer and pesticides (Bransby et al, 1998;Liebig, 2006;Sladden et al, 1991); (2) reducing runoff, reducing soil erosion, and stabilizing stream banks as a result of increased surface roughness from vegetation structure and the well-developed rhizome and root systems of switchgrass (Gyssels and Poesen, 2003); (3) decreasing drought and flood impacts on production since perennial grass feedstocks, especially cordgrass, are tolerant to drought, flood, and salinity (Kim et al, 2010); (4) increasing economic returns due to reduced usage of irrigation water; (5) improving wildlife habit (e.g., providing cover during critical nesting periods for grassland birds) (Murray et al, 2003;Robertson et al, 2012;Schaap, 2011; http://www.michigandnr. com/publications/pdfs/huntingwildlifehabitat/landowners guide/ species mgmt/pheasants.htm) and plant vigor (i.e., carbohydrate reserves), and retaining nitrogen because of late, post-senescence harvest for cellulosic biofuels (Garland, 2010); (6) improving carbon sequestration and carbon retention (i.e., carbon sinks) (Bransby et al, 1998;Frank et al, 2004;Ma et al, 2000;Zeri et al, 2011); and (7) reducing dependency on foreign oil.…”

Neopolyploidy in Spartina pectinata Link: 1. Morphological analysis of tetraploid and hexaploid plants in a mixed natural population

“…Chromosome preparation was done according to the cell-squashing technique described by Kim et al (2010). The collected root tips were pretreated with *15 ml of 0.05% 8-hydroxyquinoline for approximately 2 h and fixed at room temperature for 4 days in a 3:1 ratio of ethanol to acetic acid.…”

“…Prairie cordgrass (S. pectinata Link), reported to have multiple cytotypes, including tetraploid (2n = 4x = 40), hexaploid (2n = 6x = 60), and octoploid (2n = 8x = 80) (Kim et al 2010(Kim et al , 2012, offers a convenient model to study intraspecific autopolyploids. Prairie cordgrass is distributed throughout the eastern coast and inland marshes of the Midwest United States to Alberta, Canada (Barkworth et al 2007).…”

“…In contrast, a hexaploid prairie cordgrass seed harvest from a tetraploid plant is very rare. The first hexaploid prairie cordgrass was found in seedlings grown from seeds harvested from a tetraploid plant (Kim et al 2010). Unlike the hexaploid prairie cordgrass previously found, a more recent hexaploid was discovered as inhabiting a heterogeneous setting with tetraploid plants at one location in Illinois (Kim et al 2012).…”

Analysis of Active Nucleolus Organizing Regions in Polyploid Prairie Cordgrass (<i>Spartina pectinata</i> Link) by Silver Staining

“…Their cytotypes and geographic distribution were already given by Kim et al (2010Kim et al ( , 2012a. The objectives of this study were to estimate the number of AgNORs, their locations, and their activities on metaphase chromosomes and to determine the heteromorphic variation in size and number of nucleoli at interphase cells for different ploidy levels in prairie cordgrass populations.…”