Prevalence,distribution and intraspecific variation of Heterodera schachtii populations from semiarid environment

A two-year survey study was carried-out to identify and determine the distribution, community characteristics and intraspecific variation of the sugar beet cyst nematode, Heterodera schachtii populations collected from the six major sugar beet-producing governorates in Syria, west Asia. A total of 178 composite rhizosphere soil samples were collected from the six governorates during 2009 and 2010 growing seasons as follows: Aleppo (26), Ar Raqqah (17), Dayr az Zawr (33), Idlib (34), Hamah (41) and Homs (27 samples). The nematode was originally identified on the basis of morphometrics and morphological features of the cyst vulvar cones and second-stage juveniles (J₂). The communities of H. schachtii were then analyzed using the criteria of frequency of occurrence (FO%), mean population density (PD) and prominence value (PV). Results showed that H. schachtii was the most frequent and prominent in Homs (FO% = 70.37% and PV = 23472.37) and the least frequent and prominent in Ar Raqqah (FO% = 5.88% and PV = 28.86). The highest nematode population density was also recorded in Homs in 2009 (50,545 J₂ + eggs/100 g soil) while the least was recorded in Ar Raqqah in 2010 (119 J₂ + eggs/100 g soil). The morphometric data of cyst vulvar cone, second-stage juveniles (J₂) and eggs were also subjected to a multivariate principal component analysis to analyze the relationships between the studied populations, and to identify the variables that show the highest multiple correlations with these populations. Results showed that at the high order of hierarchical cluster analysis, four populations (Idlib, Hamah, Homs and Aleppo) formed one main cluster, while Dair az Zawr and Ar Raqqah failed to form clusters and separated individually. However, at low distance value, the main cluster further subdivided to separate the Aleppo population from Idlib, Hamah and Homs populations. The morphometric distance values ranged from 0.07 to 0.61. Hamah and Homs were the closest populations while Dair az Zawr showed the most diverse population. This study also revealed the value of J₂ body length, egg length and width, fenestral length and width and the number of bullae inside the cyst vulvar cone in determining the intraspecific variations among the Syrian populations of H. schachtii.     

A Key and Compendium to Species of the Heterodera avenae Group (Nematoda: Heteroderidae)

A key based on cyst and juvenile characters is given for identification of 12 valid Heterodera species in the H. avenae group. A compendium providing the most important diagnostic characters for use in identification of species is included as a supplement to the key. Cyst characters are most useful for separating species; these include shape, color, cyst wall pattern, fenestration, vulval slit length, and the posterior cone including presence or absence of bullae and underbridge. Also useful are those of second-stage juvenile characteristics including aspects of the stylet knobs, tail hyaline tail terminus, and lateral field. Photomicrographs of diagnostically important morphological features complement the compendium.     

Effects of varying temperature on the reproduction and damage potential of Heterodera schachtii to Chinese cabbage (Brassica rapa pekinensis)

Heterodera schachtii is a well-known, destructive pathogen of Chinese cabbage (Brassica rapa pekinensis) in Korea, and several studies have attempted to find a potential control measure against it. This study is the first to investigate the effects of varying temperature on the reproduction and damage potential of H. schachtii to Chinese cabbage. Chinese cabbage plants were inoculated with H. schachtii at different densities (1, 2, or 4 juveniles per gram of soil) and grown under three temperature regimes: constant (15, 20, or 25 °C), increasing (10, 14, and 18 °C), and fluctuating (positive, 16.7–22.0 °C; negative, 21.5–11.5 °C). At a constant temperature after 30 days of inoculation, both Chinese cabbage and H. schachtii performed best at 20 °C. However, after 60 days of inoculation, H. schachtii had a significantly higher population at 20 °C, whereas cabbage growth was best at 25 °C. With increasing temperature, the numbers of cysts and females did not change significantly, and reached maxima at an initial temperature of 14 °C. However, the number of leaves and weights of the Chinese cabbage plants significantly differed at 14 °C. Under fluctuating temperatures, temperature decreases reduced the H. schachtii population.     

Comparative Morphometrics of Eggs and Second-Stage Juveniles of Heterodera schachtii and a Race of H. trifolii Parasitic on Sugarbeet in The Netherlands

Measurements of second-stage juveniles of Heterodera schachtii from California and The Netherlands and a race of H. trifolii from The Netherlands were obtained and compared to determine if these populations can be differentiated by morphometrics. Juvenile lengths of 10 specimens from each of 10 cysts of each population were measured. Dimensions of tail regions of 20 juveniles from individual cysts of H. schachtii (California) and a like number of juveniles of H. trifolii (The Netherlands) were also obtained. The mean lengths of juveniles of H. schachtii from California and The Netherlands were not significantly different, but similar measurements of H. schachtii and H. trifolii were different (P = 0.05). Mean dimensions of tail lengths, tail widths, tail hyaline lengths, and tail length/tail width were significantly greater for H. trifolii than for H. schachtii. Also, dimensions of eggs of H. trifolii were significantly greater than dimensions of H. schachtii eggs. The investigations established that H. schachtii can be readily differentiated from H. trifolii by morphometrics of eggs and juveniles, Minimum sample sizes required for specified confidence intervals for each criterion measured are provided.     

Fine Structure of the Cone of Heterodera schachtii with Emphasis on Musculature and Fenestration

Fine structure of the posterior cone of monoxenically cultured Heterodera schachtii is examined. The cone is not evident at the end of the fourth molt, but as the female matures the cone elongates, vulval lips enlarge, and cuticular patterns on the lips are modified. Body wall cuticle (BW) of the cone includes layers A and B, but C is modified or replaced by a network of fibers which correspond to the semifenestrae. Vaginal lining is continuous with the BW and terminates at the cuticular underbridge near the uterus. Vaginal musculature includes 48 dilatores vaginae (DV) as well as a sphincter vaginae (SV). The DV include a contractile and noncontractile region with abundant actin and glycogen. A distinct anal depressor muscle is present. In the cyst, only bullae, the underbridge, vagina lining, and traces of the SV muscle persist. Detailed morphology of the cone of H. schachtii provides insight into characters which, when compared with other heteroderines, will be useful in phylogenetic analysis of Heteroderinae.     

Molecular Polymorphism and Morphometrics of Species of the Heterodera avenae Group in Syria and Turkey

Molecular characterization of the three most common cereal cyst nematode species of the Heterodera avenae group (H. avenae, H. filipjevi, and H. latipons), originating from various locations in major cereal-cultivating areas in Syria and Turkey, showed distinct restriction fragment patterns of the ITS-rDNA following PCR amplification and RFLP digestion with four endonucleases (Hae III, Hinf I, Ita I, and Pst I). Genetic dissimilarity within H. avenae group populations increased in comparison with H. avenae and other species; it was 0.164 with H. filipjevi and 0.354 with H. latipons populations. No intraspecific polymorphism was observed within H. latipons or H. filipjevi populations. Principal component analysis revealed contrasted correlations among 12 morphological parameters of cysts and juveniles of the three Heterodera species that separated them and distinguished differences within populations of H. latipons. Our results showed a clear separation of the three cyst nematode species on cereal using a conventional method for classification and molecular tests, and confirmed the congruence between genetics and morphological traits.     

Redescription of Heterodera fici (Nematoda: Heteroderidae) with SEM Observations

Heterodera fici is redescribed and illustrated with comparative details and revised measurements and diagnostic characters of the females, males, cysts, and juveniles from Maryland and Pakistan. This species is in the "schachtii group" (cysts lemon shaped, with bullae, and ambifenestrate) but the fenestrae in some cysts, presumab!y young ones, are small and widely spaced, appearing bifenestrate. It is most closely related to H. schachtii, H. glycines, and H. cajani but differs from these species especially in having cysts with small, scattered bullae and weakly developed underbridge; and males with four small nipples on tail tip. Scanning electron microscopy (SEM) observations of the specimens are also presented. The relationship of this species to closely related forms is discussed.     

Morphometric and Serologic Comparisons of a Number of Populations of Cyst Nematodes

Thirty-five populations of Heterodera glycines and populations of 15 other Heterodera, Globodera, and Punctodera species were studied morphometrically and some were compared serologically. There was a wide range of each measurement within each nematode population. Except for one soybean cyst nematode population from Indiana, which was a tetraploid and considerably larger than the others, morphometric measurements overlapped. In a discriminant function comparison most of the populations were closely grouped but at least three were rather distinctly separated. Morphometrically H. fici, H. cruciferae, H. schachtii, and H. trifolii were closely associated with H. glycines. Serology indicated a close relationship between H. glycines, H. lespedezae, H. trifolii, H. schachtii, and the Heterodera sp. from Rumex, while H. betulae appeared to be more distantly related.     

Effect of Phenamiphos on Heterodera schachtii and Meloidogyne javanica

Aqueous solutions of technical-grade phenamiphos [ethyl 3-methyl-4-(methylthio) phenyl (1-methylethyl) phosphoratnidale] were used in hatching chambers to test, under laboratory tory conditions, the effect of phenamiphos on the hatching and movement of Meloiclogyne javanica and Heterodera schachtii. Hatch of M. javanica and H. schachtii eggs was depressed 70 and 88% by nematicide at 0.48 and 4.80 μg/ml, respectively. The infectivity of second-stage larvae of both species was affected by concentrations as low as 0.01 μg/ml. At least 0.5 μg/ml was required to decrease the movement of larvae of M. javanica and H. schachtii. To decrease the movement of H. schachtii males toward females, 10 μg/ml was required. In a field experiment using a 15% granular formulation, 5 kg/ha a.i. significantly reduced infection of sugarbeet roots by H. schachtii.     

Relationships among udder characteristics,milk yield and,non-yield traits in Frizarta dairy sheep

In the present study the relationships between five body structural and nine udder morphological traits with milk yield and non-yield traits, i.e. milk contents, somatic cell count and body weight in n = 171 Frizarta ewes were investigated. Positive correlations of moderate to high magnitude were observed among body measurements ranging from 0.25 (body length-chest width) to 0.61 (chest width-chest girth). High correlations were observed between udder width and udder circumference (r = 0.69) as well as between udder circumference at base and middle (r = 0.62). Udder height was found to be positively correlated with cistern depth (r = 0.32), udder width (r = 0.40) and udder circumference (r = 0.42) as well as with teat measurements (0.19 and 0.25 with teat length and teat circumference, respectively). Cistern depth was positively and highly correlated with teat angle (r = 0.64). The correlation between teat length and circumference was also high (r = 0.57). Teat angle was found to be negatively correlated with teat measurements (r = −0.39 and −0.23 for teat length and teat circumference, respectively). Principal components analysis revealed four components that jointly explained 67% of the variance of all the body and the udder morphological traits. The first principal component interpreted as the body dimensions was found to be associated with body weight of ewes. The second component interpreted as global and rear measurements of the udder was significant for milk yield traits. The third and fourth principal components were interpreted as the udder type and teat dimensions, respectively. Ewes’ body weight could be adequately predicted by chest girth, body length, chest width and withers height. Test day milk yields were found to be associated with udder circumference and udder width as well as with udder height and teat length. None of the udder measurements and/or teat characteristics was found to be correlated with milk content(s) and/or somatic cell count. New statistical techniques can be successfully implemented in investigation of relationships between various traits in dairy sheep.     

The Interrelationship of Heterodera schachtii and Ditylenchus dipsaci on Sugarbeet

Heterodera schachtii significantly (P = 0.05) reduced sugarbeet root growth below that of uninoculated controls at 20, 24, and 28 C, and Ditylenchus dipsaci significantly (P = 0.05) reduced root growth below that of uninoculated controls at 16, 20, 24, and 28 C. A combination of H. schachtii and D. dipsaci significantly (P = 0.05) reduced root growth below that of single inoculations of H. schachtii at all temperatures and D. dipsaci at 20, 24, and 28 C. Single inoculations of H. schachtii and D. dipsaci significantly (P = 0.05) reduced top growth of sugarbeet below that of uninoculated controls at 20, 24, and 28 C, and 16, 20, 24, and 28 C, respectively. A combination of the two nematodes significantly (P = 0.05) reduced top growth below that of single inoculations of H. schachtii at all temperatures. However, a combination of the two nematodes failed to significantly (P = 0.05) reduce top growth below that of single inoculations of D. dipsaci at any temperature. Inoculations of either H. schachtii or D. dipsaci did not affect penetration of the other nematode, and D. dipsaci did not affect development and reproduction of H. schachtii. D. dipsaci did not reproduce on sugarbeet.     

Oral morphology and dietary choices of goats on rangeland

The morphometrics of mandible and teeth of mixed-breed goats on rangeland were analyzed to investigate the association between the oral apparatus and diet type. Canonical relationship between sets of mandible measurements (7) and main plants ingested (17) indicated that, overall, oral characteristics tended to modify ingestive behavior (canonical correlation = 0.81). In general, incisor length had a greater effect (absolute value of standardized coefficient: AVSC = 0.56) on ingestion of Nolina cespitifera than did other mandible variables. Incisor width influenced the ingestion of Parthenium incanum (AVSC = 0.47) and Flourensia cernua (AVSC = 0.43). Distance between the bases of the last most lateral incisors (I₄ or corners) was associated with the ingestion of Atriplex canescens (AVSC = 0.54) and Florensia cernua (AVSC = 0.69). Incisor breath was important for the consumption of Larrea tridentata (AVSC = 0.68) and Cowania plicata (AVSC = 0.50). The ingestion of Agave lechuguilla (AVSC = 0.51) and Sphaeralcea angustifolia (AVSC = 0.43) were influenced principally by muzzle width. Distance between first molars was the variable most closely associated to the ingestion of Buchloe dactyloides (AVSC = 0.51) and Croton dioicus (AVSC = 0.62). Mandible length had a greater effect on the ingestion of F. cernua and Atriplex canescens than did other oral traits. Variation in the oral apparatus did not affect percentage of grasses, forbs and shrubs of goat diets. Fecal nitrogen, fecal phosphorous and number of species consumed were not related to oral traits. These results suggest that different dimensions in the oral apparatus of grazing goats lead to divergent selection of range plants, without altering the quality of their diet.     

Pathological Differences in Heterodera schachtii Populations

Five populations of Heterodera schachtii Schm. from Oregon, Idaho, and Utah did not differ significantly in seedling penetration and rate of emergence and virulence. Another Utah H. schachtii population (Utah 2), however, differed from these five populations in all of the above-mentioned characteristics. More H. schachtii larvae of the Utah 2 population than the other populations penetrated sugarbeet seedlings at 10, 15, 20, and 25 C. Root and top weights of sugarbeet plants were signiticantly less when roots were parasitized by the Utah 2 population than when they were parasitized by larvae of the other nematode populations under similar experimental conditions. Also, the period of larval emergence was shorter in the Utah 2 population than in any of the other H. schachtii populations.     

Susceptibility of plant selections to Heterodera schachtii and a race of H. trifolii parasitic on Sugarbeet in The Netherlands

Similar host ranges were found for Heterodera schachtii and a race of H. trifolii parasitic on sugarbeet in The Netherlands. Twenty-nine of 41 plant accessions evaluated were susceptible to H. trifolii. Five breeding lines of the interspecific hybrid Beta vulgaris-B. procumbens which are resistant to H. schachtii were highly susceptible to H. trifolii. An accession of B. maritima with partial resistance to H. schachtii was resistant to H. trifolii.     

Bioinformatics analysis of ubiquitin expression protein gene from Heterodera latipons

Ubiquitin expression protein DNA clone (Hl-UBI) was isolated from Heterodera latipons collected from North Jordan. Its sequence of 285 nucleotides was also determined and deposited in the GeneBank. The 285-bp open reading frame coded for 76-amino acid protein having two domains; the ubiquitin domain and the C terminal extension. The first 59 amino acids were predicted with the ubiquitin domain with identity percentages of 78% to ubiquitin of H. schachtii, 77% to polyubiquitin of Globodera pallida, 74% to ubiquitin of Globodera rostochiensis and 72% to ubiquitin of Heterodera glycines. The other domain at the C-terminus, containing 17 amino acids, showed no homology to any known protein. Sequence analysis showed a calculated encoding amino acids molecular weight of 8.77 kDa, theoretical isoelectric point = 4.76, negatively charged residues = 12, positively charged residues = 9, extinction coefficient = 1490, estimated half-life = 30 h, instability index = 32.51 and grand average of hydropathicity = ?0.537. The demonstrated subcellular localization analysis of cytoplasm, cell nucleus, mitochondrion, cell skeleton and plasma membrane of Hl-UBI protein occupied about 52.20, 21.70, 17.40, 4.30 and 4.30%, respectively. Sequence, homology and structural analysis confirmed that Hl-UBI gene was highly conserved during evolution and belonged to ubiquitin gene family.     

Oogenesis and the Chromosomes of Twelve Bisexual Species of Heterodera (Nematoda: Heteroderidae)

Twelve bisexual species of Heterodera reproduced by amphimixis and had the same number of n=9 (2n=18) chromosomes in maturing oocytes. H. schachtii had slightly larger chromosomes than all other species. Only sperm nuclei with n=9 chromosomes were observed inside maturing oocytes and no specialized sex chromosomes were detected in any case. A "supernumerary" chromosome was observed occasionally in oocytes of H. schachtii and H. weissi and was transmitted regularly to one-half of the progeny of the nematodes that possessed it. Cytological characteristics were not very instructive in differentiating amphimictic tleterodera species. Such karyotypic uniformity indicates cytogenetic stability of the genus and close interrelationship among its members.     

Effects of shell morphological traits on the weight trait of the orange strain of the Manila clam

A new strain of Manila clam with orange shell color was produced after selection within a full-sib family for two generations. In the present study, the shell length, height, and width, and the live body weight of the orange strain were measured, and their correlation coefficients were calculated. The shell morphological traits were used as independent variables, and the live body weight was used as the dependent variable for calculating the path coefficients, correlation index, and determination coefficients. The results showed that the correlation coefficients between each shell morphological trait and the live body weight were all highly significant (P < 0.01). The correlation indices (R²) of morphological traits against the live body weight of clams were larger than 0.85, indicating that the morphology traits were the main factors affecting the body weight. Multiple regression equations were obtained to estimate shell length X₁ (cm), shell height X₂ (cm), and shell width X₃ (cm) against live body weight Y (g): Y = ? 2.62 + 0.34 X₁ + 0.145 X₂, (X₁ < 0.05, X₂ < 0.05). The results suggest that the shell length could be used as the main trait for selective breeding and could indirectly make a large improvement in the weight trait.     

Spatial and temporal variation in density and thallus morphology of Turbinaria ornata in Thailand

Turbinara ornata (Turner) J. Agardh, is a common brown alga, which occurs on tropical shores worldwide. We studied the effects of wave action and seasonal variation on T. ornata populations at Koh Pling, Sirinart Marine National Park, Thailand. Density, length of thallus, length of blade, number of blades, number of reproductive organs, and dry weights were investigated. The algae were collected bimonthly during August 2003–May 2004, at three different areas of wave exposure: sheltered, semi-exposed, and exposed. There were variations in all factors at sites and seasons (P < 0.05). We found that T. ornata populations were denser on the semi-exposed shore and their biological characteristics reached their peaks during October 2003. The highest density of T. ornata was 27 ± 10 fronds/m² (mean ± S.E.). While the average frond length, for example, was 24 ± 1.5 cm, 4 times greater than the minimum; and the number of blades on the thallus were 329 ± 47 blades, 15 times greater than the minimum. Surprisingly, the population disappeared at the beginning of May 2004, and returned in July 2004. In this work, we attempt to explain the differences in various characteristics of T. ornata in relation to the degree of wave exposure, nutrient concentration and other physical factors. We also discuss how our results may provide some insight into the current rapid expansion of T. ornata populations.