feature used to differentiate species in this genus. Spike morphology varies, in a continuous fashion, from broad, The crested wheatgrass complex (Agropyron spp. Gaertn) consists pubescent, pectinate spikes to narrow, linear, glabrous of persistent, drought tolerant, tussock grasses, which originate from the steppes of central Asia and are of importance as range grasses spikes (Dewey and Asay 1982). Taxonomy is further conon the Great Plains of North America. Amplified fragment length founded by geographical overlap and a high level of crosspolymorphism (AFLP) markers were used to examine the interpopucompatibility between the species. lation relationships and to compare variances within and among 12 There are three crested wheatgrass species of compopulations from four Agropyron spp. [Agropyron cristatum (L.) mercial importance in North American rangelands. Fair-Gaertn, Agropyron desertorum (Fisch ex Link) Schlut, Agropyron way crested wheatgrass (A. cristatum) occurs in diploid, fragile (Roth) Candargy and Agropyron mongolicum Keng.] and two tetraploid, and hexaploid form. Standard crested wheatinterspecific hybrid populations. Euclidean distances were calculated grass (A. desertorum) and Siberian crested wheatgrass on the basis of marker polymorphism and a cluster analysis was per-(A. fragile) are both tetraploid. formed on these populations. Fairway, Parkway, and S9240 grouped The relationship between A. cristatum and A. deserclosely, and it is likely that these are the only true A. cristatum populations included in this study. Hycrest, CD-II, and Kirk grouped torum has been subject to extensive discussion. Knowles loosely between A. cristatum and A. desertorum. This confirms the (1955) considered A. desertorum to be either an autoploid hybrid nature of Hycrest and CD-II but may indicate that Kirk is of A. cristatum, or an amphiploid of A. cristatum and incorrectly classified as A. cristatum, but is rather a hybrid. Agropyron some other closely related diploid. A number of papers desertorum cv. Nordan clustered loosely between A. cristatum and written in the 1960s (Dewey, 1961;Tai and Dewey, 1966; A. mongolicum, which is in agreement with the suggestion that A. Pendse, 1967, 1969; concluded, desertorum is an alloploid of A. cristatum and A. mongolicum. The on the basis of meiotic chromosome pairing, that A. cultivars Vavilov, Douglas, and Ephraim clustered with A. desertorum. desertorum was an autotetraploid of A. cristatum, or a An analysis of molecular variance (AMOVA) was conducted on 15 segmental allotetraploid. Schulz-Schaeffer et al. (1963) individuals from six of the populations (Fairway, Parkway, S9240, considered Dewey's (1961) interpretation of polyha-Kirk, Hycrest, and Nordan). The majority (88%) of the AFLP variance was within populations, which was expected in these outcrossing ploid chromosome pairing to be incorrect and that A. populations; however, significant differences were still detected desertorum is a segmental allotetraploid, and not an among all six populations. Relationships among...
The two most widely grown bromegrass species in North America are smooth bromegrass, a hay type grass, and meadow bromegrass, a pasture type grass. Hybrid populations between these two species have been developed through hybridization and recurrent selection. The objective of this study was to determine the genetic relatedness of the hybrid bromegrass population S‐9073M to its parental populations using random amplified polymorphic DNA (RAPD) markers and to determine genetic variation within and between populations. Individuals from each of the three populations were genotyped at 43 polymorphic RAPD loci. One of the RAPD fragments was meadow bromegrass‐specific. Cluster analysis showed three groups representing the two parental populations and the hybrid population. An analysis of molecular variance (AMOVA), showed that the hybrid population had the highest within‐population variation, followed by meadow bromegrass and smooth bromegrass. The interpopulation genetic distance (phi‐statistic =Φst) was highest between meadow and smooth bromegrass and lowest between smooth and hybrid bromegrass. The hybrid population was genetically intermediate to smooth bromegrass and meadow bromegrass, but closer to smooth bromegrass, possibly reflecting the selection criteria used in the development of this hybrid.
Three hybrid populations between meadow bromegrass (Bromus riparius Rehm.) and smooth bromegrass (Bromus inermis Leyss) have been developed through hybridization and recurrent selection. The objective of this study was to determine the concentration of acid detergent fiber (ADF), neutral detergent fiber (NDF), and crude protein (CP) of leaf blades, stems, and whole‐plant herbage of three hybrid bromegrass populations (S‐9197, S‐9073 and S‐9183) and the two parental species at vegetative, heading, and anthesis stages of development. Generally, the highest leaf blade NDF, ADF, and lowest CP concentrations were observed in meadow bromegrass, regardless of the growth stage. For the stem fraction, hybrid S‐9183 had the lowest ADF (240 g kg−1) and NDF (532 g kg−1) at the vegetative stage. At anthesis, in 1997, stem NDF concentrations of meadow bromegrass, S‐9197, and S‐9073 were similar, but lower than S‐9183 and smooth bromegrass. At later stages of development, meadow bromegrass had higher stem CP concentrations (94–114 g kg−1) than other entries (62–110 g kg−1). For whole‐plant samples, NDF (359–490 g kg−1) and ADF (178–214 g kg−1) concentrations of the three hybrid populations were consistently lower than the parental species at the vegetative stage of growth. The hybrid populations, particularly S‐9183, were lower in NDF and ADF at early stages of maturity, suggesting that they have potential as high quality forage species for grazing and hay prior to or at heading.
Ferdinandez, Y. S. N. and Coulman, B. E. 2000. Characterization of meadow ؋ smooth bromegrass hybrid populations using morphological characteristics. Can. J. Plant Sci. 80: 551-557. Three hybrid populations between meadow bromegrass (Bromus riparius Rehm.) and smooth bromegrass (Bromus inermis Leyss.) have been developed using recurrent selection for vigor, uniformity of growth and floret fertility. The objective of this study was to use morphological characters to characterize the three hybrid populations (S-9197, S-9073, and S-9183) and the two parental species. Tiller heights did not differ among the hybrids and the parental species. Leaf-to-stem ratio of the hybrids was intermediate to that of the parents. Tiller density, panicle density and dry matter yield of the hybrids were more similar to those of smooth bromegrass. Leaf pubescence densities of the hybrids were higher than the parental species, but pubescence lengths closely resembled meadow bromegrass. Leaf area index (LAI) of the hybrids was lower than smooth bromegrass, and resembled meadow bromegrass. Lowest brown leaf spot ratings were observed in meadow bromegrass, while the hybrids were similar to smooth bromegrass. In general, the hybrid populations showed some individual characteristics similar to each of the parental species and, thus, can be characterized as being intermediate to the parental species. Furthermore, several of the differences among the hybrid populations can be attributed to the selection criteria that were used to develop these populations. Il n'y avait pas de différence entre hybrides et espèces parentale quant à la hauteur des talles. Le rapport feuille-tige chez les hybrides se situait entre celui des deux parents. La densité des talles et des panicules ainsi que le rendement en matière sèche des hybrides étaient plus proches de ceux du brome inerme. La pubescence de la feuille chez les hybrides était plus dense que celle des espèces parentales, mais la longueur de la pilosité ressemblait à celle du brome des prés. Les notes les plus basses pour la sensibilité à la tache foliaire brune étaient obtenues chez le brome des prés, les hybrides se comportant à cet égard comme le brome inerme. En général, les populations hybrides portaient quelques caractères semblables à chacun des deux parents. On peut donc les décrire décrites comme étant intermédiaires entre les deux. En outre, plusieurs des différences observées parmi les populations hybrides peuvent être imputables aux critères de sélection utilisés dans la constitution des populations.
tively expensive for large-scale plantings. Releases of a commercial Minnesota ecotype in 1995 and the USDA Blue grama [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths]ecotype Bad River originating from South Dakota in is one of the most widespread native grasses in western North America.1996 have improved the seed supply of blue grama. As Several blue grama seed sources are currently used for rangeland these ecotypes represented germplasm selected from seeding, but little is known about the genetic diversity of these seed sources. Amplified fragment length polymorphism (AFLP) technique single native sites, however, concern has been raised was applied to compare the genetic diversity among four blue grama that these plant materials may lack the genetic diversity seed sources (a precultivar germplasm [balanced multisite composite, to maintain adaptation in dynamic, nonlocal environ-BMSC], the ecotype Bad River, a Minnesota ecotype, and a native ments (Knapp and Rice, 1996; Roundy, 1999; Larson et Manitoba seed collection) and to assess the genetic shift during two al., 2000). To address this concern, a BMSC was develgenerations of BMSC seed multiplication. Germplasm BMSC was a oped in 2000 from 495 live plants collected from 11 balanced multisite composite of 99 clones selected from 495 live plants sites across Manitoba (Phan, 2000). While the BMSC collected from 11 sites across Manitoba. Six AFLP primer pairs were is expected to maintain higher genetic diversity than the employed to screen a total of 176 individual plants sampled from both other seed sources, no comparison of genetic diversity the first three generations of BMSC and the other three seed sources has been made among them. Even though the BMSC and 167 polymorphic AFLP bands were scored for each plant. Large AFLP variation was observed within the four seed sources. Greater had been shown to capture most of the RAPD variations AFLP variation was detected in the BMSC than Bad River, Minnesota present in its source populations (Phan et al., 2003), it ecotype, and the Manitoba native harvest. No genetic shift in the still remains unknown if genetic shift has occurred dur-BMSC was found across the two seed multiplications. These results ing successive generations of the BMSC seed multipliindicate a balanced composite of multisite blue grama germplasm cation.can maintain high genetic diversity with little genetic shift in a few
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