Changes in western wheatgrass foliage quality following defoliation: consequences for a graminivorous grasshopper

We determined the effects of defoliation by a graminivorous grasshopper on the foliage quality of the C3 plant, western wheatgrass (Pascopyrum smithii [Rydb] A. Love). Additionally, we determined the effects of this defoliation upon the subsequent feeding of the graminivorous grasshopper Phoetaliotes nebrascensis Thomas (Orthoptera: Acrididae). In field and greenhouse studies, graminivorous grasshopper herbivory altered the quality of remaining western wheatgrass foliage. In the greenhouse, severe (50% foliage removal) grasshopper grazing (638 grasshoppers/m² for 72h) resulted in decreased foliar nitrogen (–12%), carbohydrate (–11%) and water (–2.5%) concentrations, and increased phenolic concentrations (+43%). These changes were associated with decreased adult female grasshopper mass gain, consumption rate, approximate digestibility, and food conversion efficiencies. In the field, moderate (14% foliage removal) grasshopper grazing (20 grasshoppers/m² for 20 days) led to a 10% reduction in foliar nitrogen concentrations. Foliage quality changes in the field were not associated with any reductions in grasshopper mass gain, consumption rates, food digestibility, or conversion efficiencies. The results presented here are consistent with the hypothesis that defoliation leads to a reallocation of carbon and nitrogen compounds within the plant such that foliage quality for P. nebrascensis is reduced.     

Anther culture of some perennial triticeae

Three field grown Agropyron spp. (crested wheatgrasses) and two Thinopyrum spp. (intermediate and tall wheatgrasses) were evaluated for anther culture response. Hormonally modified potato extract and 85D12 media induced pollen embryogenesis. Modified Murashige and Skoog media were tested for their effects on callus proliferation and plantlet regeneration. Callus induction frequency and plantlet production were highest (25.0% and 45.8%, respectively) for Thinopyrum ponticum (2N=70) (tall wheatgrass). One-hundred and nine albino plantlets were produced from T. ponticum Jose both by direct regeneration on 85D12 medium and through a callus phase from potato extract media. This is the first report of plantlet production from anther culture of a Triticeae perennial forage grass. Further experimentation with environmental and cultural conditions may result in the production of green plantlets.Abbreviations MS Murashige and Skoog (1962) medium - NAA naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - 2-ip 2-isopentenyladenosine - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid Cooperative investigations of the USDA-Agricultural Experiment Station and the Utah Agricultural Experiment Station, Logan, UT 84322. Approved as Journal Paper No. 3596     

Pathological Effects of Pratylenchus neglectus on Wheatgrasses

In controlled greenhouse and growth chamber studies, Pratylenchus neglectus reduced dry shoot and dry root weight of rangeland grasses. Greenar intermediate wheatgrass and Secar Snake River wheatgrass were more susceptible to P. neglectus than Hycrest crested wheatgrass, Fairway crested wheatgrass, and Nordan crested wheatgrass at a greenhouse bench temperature of 26 ± 3 C. Hycrest was the most tolerant to parasitism by P. neglectus. An initial nematode inoculum density of four nematodes/cm³ soil reduced dry shoot weights of Hycrest, Fairway, Nordan, Greenar, and Secar by 22%, 33%, 36%, 47%, and 49%, and reduced dry root weights by 26%, 31%, 32%, 38%, and 42%. There was a positive relationship between dry root weight, the nematode inoculum density, and the nematode reproduction index (final nematode population/initial nematode inoculum). However, there were more nematodes/g root tissue on Secar than on the crested wheatgrasses, and significantly more nematodes/g root tissue on Greenar, Fairway, and Nordan than on Hycrest. Pratylenchus neglectus was most pathogenic at four nematodes/cm³ soil at 30 C and least pathogenic at one nematode/cm³ soil at 15 C. Greenar and Secar were more susceptible to the nematode than Hycrest, Fairway, and Nordan at two and four nematodes/cm³ soil at 20 to 30 C. The nematode reproductive indices were greatest at 30 C and were positively correlated with dry root weight. Secar supported the most and Hycrest had the fewest nematodes/g root.     

Evaluating strategies for facilitating native plant establishment in northern Nevada crested wheatgrass seedings

Non‐native crested wheatgrasses (Agropyron cristatum and A. desertorum) were used historically within the Great Basin for the purpose of competing with weed species and increasing livestock forage. These species continue to be used in some areas, especially after wildfires occurring in low elevation/precipitation, formerly Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis)/herbaceous communities. Seeding native species in these sites is often unsuccessful, and lack of establishment results in invasion and site dominance by exotic annuals. However, crested wheatgrass often forms dense monocultures that interfere competitively with the establishment of desirable native vegetation and do not provide the plant structure and habitat diversity for wildlife species equivalent to native‐dominated sagebrush plant communities. During a 5‐year study, we conducted trials to evaluate chemical and mechanical methods for reducing crested wheatgrass and the effectiveness of seeding native species into these sites after crested wheatgrass suppression. We determined that discing treatments were ineffective in reducing crested wheatgrass cover and even increased crested wheatgrass density in some cases. Glyphosate treatments initially reduced crested wheatgrass cover, but weeds increased in many treated plots and seeded species diminished over time as crested wheatgrass recovered. We concluded that, although increases in native species could possibly be obtained by repeating crested wheatgrass control treatments, reducing crested wheatgrass opens a window for invasion by exotic weed species.     

Russian wheat aphid (Hemiptera: Aphididae) reproduction and development on five noncultivated grass hosts

The Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a small grains pest of worldwide economic importance. The Russian wheat aphid is polyphagous and may encounter differential selective pressures from noncultivated grass hosts. Aphid biotypic diversity can disrupt the progress of plant breeding programs, leading to a decreased ability to manage this pest. The goal of this research was to quantify Russian wheat aphid biotype 2 (RWA2) reproductive and development rates on five common noncultivated grass hosts to gain information about host quality, potential refuges, and sources of selection pressure. First, RWA2 reproduction was compared on crested wheatgrass (Agropyron cristatum, (L.) Gaertn.), intermediate wheatgrass (Elytrigia intermedia, (Host) Nevski), slender wheatgrass (Elymus trachycaulus, (Link) Gould ex Shinners), western wheatgrass (Pascopyrum smithi, (Rydb.) A. L?ve), and foxtail barley (Hordeum jubatum, (L.) Tesky) at 18–24°C. Second, RWA2 reproduction was compared on intermediate and crested wheatgrass at three temperature regimes 13–18°C, 18–24°C, and 24–29°C. At moderate temperatures (18–24°C), the intrinsic rate of increase values for all five hosts ranged from 0.141 to 0.199, indicating the possibility for strong population sources on all tested hosts. Aphids feeding on crested and intermediate wheatgrass at the 13–18°C temperature had lower fecundity, less nymph production days, longer generational times, and lower intrinsic rate of increase than aphids feeding at the 18–24°C temperature regime. Aphids feeding at 24–29°C did not survive long enough to reproduce. The positive intrinsic rates of increase in Russian wheat aphid on the wheatgrasses suggest that these grasses can support aphid populations at moderate to low temperatures.     

Relative suitability of crested wheatgrass and other perennial grass hosts for the Russian wheat aphid (Homoptera: Aphididae)

The Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), reproduces parthenogenetically in North America and must survive year-round on host plants, including in late summer when small grains are not in cultivation. During this time, cool-season perennial wheatgrasses (Poaceae: Triticeae) contribute substantially to aphid survival, crested wheatgrass (Agropyron spp.) particularly. In greenhouse studies, the number of aphids per plant was measured after four infestation periods on unvernalized and vernalized wheatgrasses. Before placement on these test plant species, aphids were reared either on winter wheat or on the grass host species on which aphid progeny were counted. On vernalized plants, aphids reared on wheat resulted in more aphids per test plant than when the aphids were reared on wheatgrasses, but on unvernalized plants the number of aphids per test plant did not differ significantly regardless of rearing host. Aphids on crested wheatgrass were similar in number to the other grasses when plants were unvernalized. However, when plants were vernalized, crested wheatgrass supported significantly more aphids than some of the other hosts. Aphid numbers increased on all test species as infestation period lengthened, and plant growth was largely unaffected by aphid feeding. These results suggest if sufficient moisture is available during summer when small grains are not in cultivation, all host species observed are capable of sustaining aphids. Crested wheatgrass is an abundant and important host of the Russian wheat aphid in its northern range of the western United States, but other less prevalent wheatgrasses also may contribute to aphid survival during late summer when small grains are not in cultivation.     

Foraging Behavior of Lacewing Larvae (Neuroptera: Chrysopidae) on Plants with Divergent Architectures

We investigated the effects of plant architecture on predator–prey interactions by quantifying the behavior of green lacewing larvae on perennial grasses with divergent leaf architectures. Crested wheatgrass produces flat, broad leaves similar to those of wheat, whereas Indian ricegrass bears linear leaves that are tightly rolled inward. In the absence of prey, lacewing time budgets and residence times were similar on the two grasses, although predators tended to search longer on crested wheatgrass. On plants infested with the Russian wheat aphid, lacewing larvae dislodged, contacted, and captured significantly more aphids on Indian ricegrass than on crested wheatgrass. Comparisons between aphid-free and aphid-infested plants suggest that differences in plant architecture modified prey accessibility rather than predator movement. Aphids on seedlings and mature plants of crested wheatgrass frequently occurred in concealed locations, such as in the rolls of immature leaves or in the blade–sheath junctions of mature leaves; aphids on Indian ricegrass were more likely to feed in exposed locations. Our focal-animal observations were consistent with results from population-level experiments and suggest that short-term, behavioral studies may help predict the effectiveness of predators at larger spatial and temporal scales.     

Factors Affecting Population Trends of Plant-Parasitic Nematodes on Rangeland Grasses

The effects of environmental conditions on population trends of plant-parasitic nematodes were studied in experimental plots of five wheatgrasses in the western Utah desert. In a 3-year (1984-86) field study, soil water and temperature affected the population trends of the ectoparasites, Tylenchorhynchus acutoides and Xiphinema americanum, and the migratory endoparasite, Pratylenchus neglectus, on Fairway crested wheatgrass, Agropyron cristatum; ''Hycrest'' crested wheatgrass, A. cristatum X A. desertorura; ''Rosana'' western wheatgrass, Pascopyrum smithii; ''Oahe'' intermediate wheatgrass, Thinopyrum intermedium; and RS-1 hybrid (Elytrigia repens X Pseudoroegneria spicata). The largest soil populations of these nematode species were collected in 1984 under good plant-growth conditions. A reduction in nematode populations occurred in 1985 and 1986, possibly because of low soil-water conditions. There was a positive relationship between high soil water and maximum population densities of T. acutoides in the spring and fall of 1984, and between low soil water and minimum population densities of the nematode in 1985 and 1986. Pratylenchus neglectus populations were affected by soil water, although to a lesser degree than the ectoparasitic nematodes. Population densities of the three nematode species were significantly lower in the drier years of 1985 and 1986 than in 1984. Nematode populations were greater at the lower soil depths in the fall than in the spring or summer.     

Soil water dynamics,transpiration, and water losses in a crested wheatgrass and native shortgrass ecosystem

The status of water in soil and vegetation was monitored in a stand of crested wheatgrass (Agropyron cristatum) and a nearby shortgrass steppe during a growing season. This was done to determine if water use and losses were similar among two very different communities in a similar climate. Precipitation was similar throughout the study period for both the crested wheatgrass and native shortgrass communities. However, the native shortgrass community with greater root biomass had consistently greater soil water depletion in the deeper soil horizons than was found in the crested wheatgrass community. Greater depletion of soil water by native shortgrass species suggests that they might be more competitive than crested wheatgrass in a water-limited environment.Crested wheatgrass maintained high leaf water potential early in the season, but lower water potential during the latter part of the growing season as compared with the major species of the shortgrass steppe, blue grama (Bouteloua gracilis) and western wheatgrass (Agropyron smithii). Leaf conductance was lower for crested wheatgrass than for the native grasses during the later part of the growing season. Consequently, seasonal transpiration for crested wheatgrass was lower when compared with blue grama or western wheatgrass. Lower conductance allowed crested wheatgrass to maintain relatively high internal water potential and may have accounted for less soil water use at deeper soil depths during the latter part of the growing season.Water loss through transpiration was less for western wheatgrass than for either blue grama or crested wheatgrass because western wheatgrass had less leaf area. However, western wheatgrass was as efficient as the other species in its use of water. Crested wheatgrass transpired more water than blue grama early in the growing season, but less than either native species for the remainder of the growing season. Estimated seasonal transpiration loss was greater in the shortgrass ecosystem than in the established crested wheatgrass stand.     

Effect of Single and Interplantings on Pathogenicity of Pratyenchus penetrans and P. neglectus to Alfalfa and Crested Wheatgrass

Alfalfa is a host of Pratylenchus penetrans and P. neglectus, whereas crested wheatgrass is a host of P. neglectus but not of P. penetrans. In a 120-day greenhouse experiment at 24 ñ 3 C, P. neglectus inhibited the growth of ''Lahontan'' alfalfa and ''Fairway'' crested wheatgrass. There were no differences in persistence and plant growth of alfalfa and crested wheatgrass, or reproduction of P. neglectus, in single plantings of alfalfa (AO) or crested wheatgrass (CWO), or in interplanted alfalfa and crested wheatgrass (ACW) treatments. On alfalfa, P. penetrans inhibited growth and reproduced more than did P. neglectus. Inhibition of plant growth and reproduction of P. penetrans was greater on alfalfa in AO than in ACW treatments. Pratylenchus penetrans did not reproduce on crested wheatgrass, but inhibited growth of crested wheatgrass in interplanted treatments and was avirulent in single planted treatments. Results were similar in a controlled growth chamber experiment at 15, 20, 25, and 30 C. Both nematode species inhibited alfalfa growth at all temperatures, and P. penetrans was more virulent than was P. neglectus to alfalfa at all temperatures and treatments. Plant growth inhibition and reproduction of P. penetrans on alfalfa in single and interplanted treatments were similar at 15-20 C, but were greater in single than in interplanted treatments at 25-30 C. Pratylenchus penetrans was avirulent to crested wheatgrass in the single planted treatments at all temperatures, but inhibited growth of crested wheatgrass in interplanted treatments at 20-30 C. Plant growth and reproduction of P. neglectus on crested wheatgrass was similar in single and interplanted treatments at 20-30 C and 15-30 C, respectively.     

Fructans in crested wheatgrass leaves

Crested wheatgrass is an important cool-season grass that has become naturalized in many semiarid regions of the western U.S. It provides ground cover and reduces soil erosion caused by water and wind. Additionally, crested wheatgrass produces important forage for livestock and wildlife on 6 to 8 million hectars of western rangeland. It is well adapted to semiarid cold desert regions because of its cool temperature growth and drought tolerance. Understanding the biosynthesis of fructans in crested wheatgrass is important because of their likely role in both cool temperature growth and drought tolerance. Recent research described a major gene (6-SFT) in crested wheatgrass that is involved in fructan biosynthesis. 1-kestotriose, the major DP3 fructan in crested wheatgrass, serves as the substrate for the two major DP4 fructans, 1&6-kestotetraose and 1,1-kestotetraose. The three major DP5 fructans are 1&6,1-kestopentaose, 1,1&6-kestopentaose and 1,1,1-kestopentaose. The major DP6 fructan is 1&6, 1&6-kestohexaose. We postulate that 1&6,1&6-kestohexaose is synthesized from the addition of a fructose to 1&6, 1-kestopentaose. This paper provides structures of the various DP 3, 4, 5 and 6 fructan types produced by crested wheatgrass and provides suggested biosynthetic pathways for all major fructan linkage types present.     

Multi-scale impacts of crested wheatgrass invasion in mixed-grass prairie

Most of North America’s northern Great Plains have been cultivated for crop production, leaving remnants of natural mixed-grass prairie fragmented and threatened by alien plant invasions. The region’s most widespread alien perennial forage crop, crested wheatgrass (Agropyron cristatum sensu amplo), has invaded native grassland and raised concerns regarding its ecological impact. To evaluate impacts at multiple scales of organization, adjacent invaded and uninvaded mixed-grass prairie were sampled at eight widely separated locations. At the population level, native C₃ mid-grasses and forbs were less abundant in invaded grasslands, while native C₃ and C₄ short-grass abundance was not different. At community and landscape levels, diversity was lower in invaded grasslands largely because of lower forb species richness and cover, and crested wheatgrass dominance of both cover (14% basal cover) and seedbank (404 seeds m⁻²). At the ecosystem level, both vegetation and litter biomass were greater in invaded grasslands, however, below ground organic matter (roots and litter), soil organic carbon, total nitrogen and phosphorus were not different. Crested wheatgrass invasion of mixed-grass prairie was associated with lower diversity within and among plant communities, and appears to simplify the composition of mixed-grass prairie landscapes. Hypotheses for crested wheatgrass dominance and persistence following invasion are suggested.     

Molecular characterisation of the low-molecular weight glutenin subunit genes of tall wheatgrass and functional properties of one clone Ee34

Wild tall wheatgrass (Lophopyrum elongatum L., 2x = 14) is an important resource for improving bread wheat (Titicum aestivum L.), including HMW-GS and LMW-GS relevant to end-use quality of the wheat flour. A set of 14 distinct sequences were amplified from the genomic DNA of the tall wheatgrass, using degenerate primers targeted at Glu-3, the locus containing the genes encoding the low-molecular weight glutenin subunits (LMW-GS). Three sequences contained an internal stop codon and were classified as pseudogenes. The other 11 all consisted of a single intron-less intact open-reading frame. An alignment of deduced protein sequences showed that the primary structure of all 11 sequences was similar to that of wheat and other wheat-related grass Glu-3 genes. All 11 sequences carried the 14 amino acid residue N-terminal motif MESNIIISFLK/RPWL, and were classified as LMW-m genes, based on the identity of the first amino acid of the mature protein. All but one of the sequences contained seven cysteine residues (the exception had 6). Their repetitive domain differs significantly from that present in Glu-3 genes isolated from the close relative intermediate wheatgrass (Thinopyrum Intermedium, 6x). A phylogenetic analysis showed that the tall wheatgrass sequences were closely related to those of the intermediate wheatgrass, but only distantly so to those from decaploid tall wheatgrass. One of the 11 LMW-GS peptides with a free-cysteine residue was heterologously expressed in E. coli and purified in sufficient scale to perform a flour supplementation test. This showed that the dough strength of bread wheat flour was significantly increased by the presence of the tall wheatgrass LMW-GS.     

Bioactive Phytochemicals and Antioxidant Capacity of Wheatgrass Treated with Salicylic Acid under Organic Soil Cultivation

This study was undertaken to determine the influence of salicylic acid (SA) on the bioactive phytochemicals and antioxidant capacity of wheatgrass extract in the organic growing medium. Wheatgrass was cultivated in SA-enriched organic growing medium, obtained from acetylsalicylic acid (aspirin) of various concentrations (0 [control], 0.25, 0.50, 1.00, and 2.00 mM) in a plant growth chamber by controlling atmosphere (20/15 °C, day/night), light (14/10 h, light/dark; light intensity 150 μmol m⁻² s⁻¹, using quantum dot light-emitting diodes), and atmospheric moisture (60 %) for 10 d. The 0.25 mM SA-treatment showed the highest impact on germination rate, wheatgrass length, weight, yield, and chlorophyll content. Levels of bioactive phytochemicals, mainly phenolic compounds, flavonoids, β-carotene, and vitamin C, were the highest in the 1.00 mM SA-treated wheatgrass extract. The DPPH radical and nitrite-scavenging capacities were the highest in the 1.00 mM SA-treated wheatgrass extract. The 0.50 mM SA-treated wheatgrass extract showed the highest superoxide dismutase-like capacity, whereas the 2.00 mM SA-treated wheatgrass extract showed the highest anthocyanin content and ABTS radical-scavenging capacity. Therefore, it might be suggested that the appropriate levels of SA-treatment were between 0.5 and 1.0 mM to enhance the bioactive phytochemicals and antioxidant capacity of wheatgrass.     

Differential Effects of Pratylenchus neglectus Populations on Single and Interplantings of Alfalfa Grasses

The invasion by three different Utah populations of Pratylenchus neglectus (UTI, UT2, UT3) was similar in single and interplantings of ''Lahontan'' alfalfa and ''Fairway'' crested wheatgrass at 24 ñ 3 °C. Population UT3 was more pathogenic than UT1 and UT2 on both alfalfa and crested wheatgrass. Inoculum density was positively correlated with an invasion by P. neglectus. Invasions by UT3 at all initial populations (Pi) exceeded that of UT1 and UT2 for both single and interplanted treatments. The greatest reductions in shoot and root weights of alfalfa and crested wheatgrass were at a Pi of 8 P. neglectus/cm³ soil. Pi was negatively correlated with alfalfa and crested wheatgrass shoot and root growth and nematode reproduction. The reproductive factor (Rf) for UT3 exceeded that of UT1 and UT2 in single and interplantings at all inoculum levels. There were no differences in Rfin the Utah populations in single or interplantings. A nematode invasion increased with temperature and was greatest at 30 °C. Population UT3 was more pathogenic than UT1 and UT2 and reduced shoot and root growth at all soil temperatures. Populations UT1 and UT2 reduced shoot and root growth at 20-30 °C. Soil temperature was negatively correlated with shoot and root growth and positively correlated with nematode reproduction. Reproduction of UT3 exceeded that of UT1 and UT2 at all soil temperatures.     

Copper uptake kinetics in hydroponically-grown durum wheat (Triticum turgidum durum L.) as compared with soil’s ability to supply copper

This paper focuses on the causes of zonation on agricultural land affected by secondary salinity between two halophytic grasses, puccinellia (Puccinellia ciliata Bor. cv. Menemen) and tall wheatgrass (Thinopyrum ponticum (Podp.) Z.-W. Liu & R.R.-C. Wang cv. Tyrrell). We hypothesized that the differences in zonation of puccinellia and tall wheatgrass were caused primarily by differences in the tolerance of these two species to waterlogging under saline conditions. This hypothesis was tested by conducting experiments in the field and in the glasshouse in irrigated sand cultures. At a saltland field site, locations dominated by puccinellia had EC_e values that were consistently higher (11–12 dS/m in early spring, and 5–9 dS/m in late summer) than locations dominated by tall wheatgrass. However locations dominated by puccinellia also had a watertable that was shallower (0.07–0.09 m in the high rainfall season; 0.11–0.13 m in the low rainfall season) than locations dominated by tall wheatgrass. In the glasshouse both species had similar growth responses to salinity under drained conditions, with a 50% decrease in shoot dry mass (DM) at ～300 mM NaCl. However, the combination of salinity (250 mM NaCl) and waterlogging increased puccinellia shoot DM by 150% but decreased shoot DM of tall wheatgrass by 90% (compared with salinity alone). Under saline/waterlogged conditions, puccinellia showed better exclusion of Na⁺ and maintenance of K⁺/Na⁺ in the shoots than tall wheatgrass. We conclude that the zonation of puccinellia and tall wheatgrass is associated with differences in their ion regulation which leads to substantial differences in their growth under saline/waterlogged conditions.     

Amidohydrolase activity,soil N status,and the invasive crucifer Lepidium latifolium

Wetlands and riparian habitats in the western United States are being invaded by the exotic crucifer Lepidium latifolium (perennial pepperweed, tall whitetop). It was hypothesized that L. latifolium was an effective competitor due to its ability to make available and take up more nitrogen than vegetation it is replacing. The hypothesis was tested by comparing amidohydrolase activities, available soil N, 30 day aerobic N-mineralization rates, and plant uptake of N in paired L. latifolium invaded and non-invaded plots occupied by Elytrigia elongata (tall wheatgrass). Attributes were measured by date (June 1998, September 1998, April 1999, and May 2000) and by soil depth (0–15, 15–30, 30–50, and 50–86 cm). Lepidium latifolium invaded sites had significantly (p 0.05) greater urease, amidase, glutaminase, and asparaginase activities than sites occupied by E. elongata for most dates and soil depths. In addition, despite far greater uptake of N per unit area, L. latifolium sites still had significantly greater available N and N-mineralization potentials than E. elongata for most dates and depths. In general, enzyme activities significantly correlated with available soil N, with a stronger relationship for sites invaded by L. latifolium. There were few significant linear correlations of enzyme activities with net N mineralization potentials for L. latifolium sites, but many for sites occupied by E. elongata. These data support the working hypothesis.     

The place of asymmetric somatic hybridization in wheat breeding

Since its first development some 40 years ago, the application of the somatic hybridization technique has generated a body of hybrid plant material involving a wide combination of parental species. Until the late 1990s, the technique was ineffective in wheat, as regeneration from protoplasts was proving difficult to achieve. Since this time, however, a successful somatic hybridization protocol for wheat has been established and used to generate a substantial number of both symmetric and asymmetric somatic hybrids and derived materials, especially involving the parental combination bread wheat and tall wheatgrass (Thinopyrum ponticum). This review describes the current state of the art for somatic hybridization in wheat and focuses on its potential application for wheat improvement.     

Introgression of bread wheat chromatin into tall wheatgrass via somatic hybridization

Regenerates were obtained following somatic hybridization between tall wheatgrass (Agropyron elongatum) and bread wheat (Triticum aestivum cv. Jinan177) protoplasts. Two lines (CU and XI) were self-fertile in the first (R₀) and subsequent (R₁ and R₂) generations. The phenotype of each R₁ population was uniform. All CU progeny were phenotypically similar to the tall wheatgrass parent, while XI progeny had thinner, smoother and softer leaves. Cytological analysis showed that more wheat chromatin was present in the hybrid callus than in the R₁ and R₂ plants, and that some intercalary translocations of wheat chromosome segments were retained in the R₂ generation. AFLP profiling confirmed the presence of wheat DNA in the introgression lines. Analysis of the high molecular weight glutenin subunit content of derived seed identified three novel subunits, not present in either the wheat or the tall wheatgrass parent. Microsatellite-based profiling of the chloroplast genome of the introgression lines suggested that only chloroplast sequences from the tall wheatgrass parent were present. The specifically inherited phenomena and possible application of these hybrids are discussed. Haifeng Cui and Zhiyong Yu were contributed equally to this article.     

Soil boron and selenium removal by three plant species

High concentrations of boron (B) and selenium (Se) naturally found in the environment are detrimental to sustainable agriculture in the western USA. Greenhouse pot experiments were conducted to study B and Se uptake in three different plant species; Brassica juncea (L.) Czern (wild brown mustard), Festuca arundinacea Schreb. L. (tall fescue), and Brassica napus (canola) were grown in soil containing naturally occurring concentrations of 3.00 mg extractable B kg^–1 and 1.17 mg total Se kg^–1 soil. During the growing season, four intermediate harvests were performed on wild mustard and tall fescue. Final harvest I consisted of harvesting wild mustard, canola, and clipping tall fescue. Final harvest II consisted of harvesting wild mustard, which had been planted in soil in which wild mustard was previously grown, and harvesting previously clipped tall fescue. The greatest total amount of above ground biomass and below surface biomass was produced by tall fescue. Plants were separated into shoots and roots, weighted, and plant tissues were analyzed for total B and Se. The highest concentrations of tissue B were recovered in shoots of wild mustard and canola at final harvest I, while roots from tall fescue contained the highest concentrations of B irrespective of the harvest. Tissue Se concentrations were similar in all plants species. Soils were analyzed for residual B and Se. Extractable soil B concentrations at harvest times were lowered no less than 32% and total Se no less than 24% for all three species. The planting of wild mustard, canola, or tall fescue can reduce water-extractable B and total Se in the soil.