Genetic Discrimination of <Emphasis Type="Italic">Catharanthus roseus</Emphasis> Cultivars by Pyrolysis Mass Spectrometry

Pyrolysis mass spectrometry (PyMS) is a rapid, simple, high-resolution analytical method based on thermal degradation of complex materials in a vacuum. It is widely applied to the discrimination of closely related microbial strains. Leaf samples from eight cultivars (‘Apricot Delight’, ‘Cooler Grape’, ‘Cooler Peppermint’, ‘Equator Grape’, ‘Equator Rose’, ‘Equator White’, ‘Equator White Eye’, and ‘Little Bright Eye’) of Catharanthus roseus were subjected to PyMS for spectral fingerprinting. Discriminant analysis (DA) of PyMS data enabled us to assign these cultivars to discrete clusters. A hierarchical dendrogram based on DA provided a possible relationship among them that was in general agreement with a previously reported classification of the cultivars based on DNA fingerprints. Furthermore, those belonging to the same ‘series’ were grouped into a single cluster, which previously could not be achieved through similar approaches based on Fourier transform infrared spectroscopy or ¹H NMR data. Overall results suggest that chemical differences (i.e., in pyrolysate composition) among cultivars, as detected by mass spectrometry, reflect their genetic variation.     

AFLP analysis of nephthytis (Syngonium podophyllum Schott) selected from somaclonal variants

This study analyzed genetic differences of 19 cultivars selected from somaclonal variants of Syngonium podophyllum Schott along with their parents as well as seven additional Syngonium species and six other aroids using amplified fragment length polymorphism (AFLP) markers generated by 12 primer sets. Among the 19 somaclonal cultivars, ‘Pink Allusion’ was selected from ‘White Butterfly’. Tissue culture of ‘Pink Allusion’ through organogenesis resulted in the development of 13 additional cultivars. Self-pollination of ‘Pink Allusion’ obtained a cultivar, ‘Regina Red Allusion’, and tissue culture propagation of ‘Regina Red Allusion’ led to the release of five other cultivars. The 12 primer sets generated a total of 1,583 scorable fragments from all accessions, of which 1,284 were polymorphic (81.9%). The percentages of polymorphic fragments within ‘White Butterfly’ and ‘Regina Red Allusion’ groups, however, were only 1.2% and 0.4%, respectively. Jaccard's similarity coefficients among somaclonal cultivars derived from ‘White Butterfly’ and ‘Regina Red Allusion’, on average, were 0.98 and 0.99, respectively. Seven out of the 15 cultivars from the ‘White Butterfly’ group and three out of six from the ‘Regina Red Allusion’ group were clearly distinguished by AFLP analysis as unique fragments were associated with respective cultivars. The unsuccessful attempt to distinguish the remaining eight cultivars from the ‘White Butterfly’ group and three from the ‘Regina Red Allusion’ group was not attributed to experimental errors or the number of primer sets used; rather it is hypothesized to be caused by DNA methylation and/or some rare mutations. This study also calls for increased genetic diversity of cultivated Syngonium as they are largely derived from somaclonal variants.     

Selection of Highly Informative Microsatellite Markers to Identify Pollen Donors in ‘Hass’ Avocado Orchards

‘Hass’ is the most popular avocado (Persea americana Mill.) cultivar in the world. It has been characterized as a crop requiring cross-pollination. However, the potential extent of self-pollination and the most effective pollen donors (best cross-pollinizing cultivars) have not been determined. In this study, 56 markers were screened against ‘Hass’ and nine commonly used pollinizing cultivars grown in southern California: ‘Bacon,’ ‘Ettinger,’ ‘Fuerte,’ ‘Harvest,’ ‘Lamb Hass,’ ‘Marvel,’ ‘Nobel,’ ‘Sir Prize,’ and ‘Zutano.’ Seventeen microsatellite, i.e., simple sequence repeat (SSR) markers, were found to be very promising for paternity analysis. Four highly informative SSR markers were selected to accurately and unequivocally identify pollen parents of ‘Hass’ fruit from an orchard interplanted with these pollinizing cultivars. From 2003 to 2006, 7,984 ‘Hass’ fruit were analyzed for their paternity. Overall, the pollen parents of 99.55% of the analyzed fruit could be unequivocally identified with a single multiplex polymerase chain reaction (PCR). Only 36 fruits (<0.45%) required a second PCR reaction to reach unequivocal identification of the pollen parents.     

Response of antioxidant activity to excess copper in two cultivars of <Emphasis Type="Italic">Brassica campestris</Emphasis> ssp. <Emphasis Type="Italic">chinensis</Emphasis> Makino

Changes in ascorbic acid content and antioxidant enzyme activities were investigated in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) leaves of ‘Wutacai’ and ‘Erqing’ exposed to excess copper (Cu). Cu treatment reduced the fresh weight of shoot and root by 57% and 46% in ‘Wutacai’, and 60 and 54% in ‘Erqing’, respectively. The accumulation of copper in leaves was higher in ‘Wutacai’ than that in ‘Erqing’. Compared to the control, ascorbic acid (AsA) contents were significantly decreased after copper treatment in both cultivars, while they were higher in ‘Wutacai’ than in ‘Erqing’, which may explain the higher copper-tolerance of ‘Wutacai’ with higher copper accumulation. The higher AsA contents of ‘Wutacai’ resulted from their lower activities of degrading enzymes, such as ascorbate oxydase (AAO) and ascorbate peroxidase (APX), as well as the increasing activity of dehydroascorbate reductase (DHAR) after copper treatment compared with ‘Erqing’. Copper stimulated superoxide dismutase (SOD) activity in both cultivars, but for catalase (CAT), there was little difference between both cultivars. Peroxidases (POD) activity was decreased after copper treatment in ‘Erqing’, while in ‘Wutacai’, it was significantly increased at 14 days, and POD activity was higher in ‘Wutacai’ than that in ‘Erqing’ at 21 and 28 days. Therefore, the induced increasing activity of POD in ‘Wutacai’ also played an important role in its copper tolerance.     

Osmoregulation and osmoprotection in the leaf cells of two olive cultivars subjected to severe water deficit

In this study, we compared the efficacy of defense mechanisms against severe water deficit in the leaves of two olive (Olea europaea L.) cultivars, ‘Chemlali’ and ‘Meski’, reputed drought resistant and drought sensitive, respectively. Two-year old plants growing in sand filled 10-dm³ pots were not watered for 2 months. Changes in chlorophyll fluorescence parameters and malondialdehyde content as leaf relative water content (RWC) decreased showed that ‘Chemlali’ was able to maintain functional and structural cell integrity longer than ‘Meski’. Mannitol started to accumulate later in the leaves of ‘Chemlali’ but reached higher levels than in the leaves of ‘Meski’. The latter accumulated several soluble sugars at lower dehydration. ‘Chemlali’ leaves also accumulated larger quantities of phenolic compounds which can improve its antioxidant response. Furthermore, the activity of three antioxidant enzymes catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) increased as leaf RWC decreased. However, differences were observed between the two cultivars for CAT and POD but not for APX. The activity of the first two enzymes increased earlier in ‘Meski’, but reached higher levels in ‘Chemlali’. At low leaf hydration levels, ‘Chemlali’ leaves accumulated mannitol and phenolic compounds and had increased CAT and POD activities. These observations suggest that ‘Chemlali’ was more capable of maintaining its leaf cell integrity under severe water stress because of more efficient osmoprotection and antioxidation mechanisms.     

Genetic diversity amongst landraces of a dioecious vegetatively propagated plant,betelvine (<Emphasis Type="Italic">Piper betle</Emphasis> L.)

Betelvine (Piper betle L., family Piperaceae) is an important, traditional and widely cultivated crop of India. The cultivators and consumers recognize more than 100 cultivars (landraces) based on regional and organoleptic considerations, while in terms of phytochemical constituents only five groups have been identified for all the landraces. Since betelvine is an obligate vegetatively propagated species, genomic changes, if any, may have become ‘fixed’ in the landraces. We carried out random amplified polymorphic DNA (RAPD) analysis in several landraces considered in four groups, namely, ‘Kapoori’, ‘Bangla’, ‘Sanchi’ and ‘Others’ in order to ascertain their genetic diversity. On the basis of the data from eleven RAPD primers, we distinguished genetic variation within and among the four groups of landraces. The results indicate the’Kapoori’ group is the most diverse. The neighbour joining (NJ) tree after a bootstrap (500 replicate) test of robustness clearly shows the four groups to be well separated. Interestingly, all known male or female betelvine landraces have separated in the NJ tree indicating an apparent gender-based distinction among the betelvines.     

QTL analysis for aphid resistance and growth traits in apple

The rosy apple aphid (Dysaphis plantaginea), the leaf-curling aphid (Dysaphis cf. devecta) and the green apple aphid (Aphis pomi) are widespread pest insects that reduce growth of leaves, fruits and shoots in apple (Malus × domestica). Aphid control in apple orchards is generally achieved by insecticides, but alternative management options like growing resistant cultivars are needed for a more sustainable integrated pest management (IPM). A linkage map available for a segregating F₁-cross of the apple cultivars ‘Fiesta’ and ‘Discovery’ was used to investigate the genetic basis of resistance to aphids. Aphid infestation and plant growth characteristics were repeatedly assessed for the same 160 apple genotypes in three different environments and 2 consecutive years. We identified amplified fragment length polymorphism (AFLP) markers linked to quantitative trait loci (QTLs) for resistance to D. plantaginea (‘Fiesta’ linkage group 17, locus 57.7, marker E33M35–0269; heritability: 28.3%), and to D. cf. devecta (‘Fiesta’ linkage group 7, locus 4.5, marker E32M39–0195; heritability: 50.2%). Interactions between aphid species, differences in climatic conditions and the spatial distribution of aphid infestation were identified as possible factors impeding the detection of QTLs. A pedigree analysis of simple sequence repeat (SSR) marker alleles closely associated with the QTL markers revealed the presence of the alleles in other apple cultivars with reported aphid resistance (‘Wagener’, ‘Cox’s Orange Pippin’), highlighting the genetic basis and also the potential for gene pyramiding of aphid resistance in apple. Finally, significant QTLs for shoot length and stem diameter were identified, while there was no relationship between aphid resistance and plant trait QTLs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effects of exogenous B supply on growth, B accumulation and distribution of two navel orange cultivars

To investigate the effects of boron (B) on growth, B concentration and distribution of two navel orange cultivars, ‘Newhall’ (Citrus sinensis Osbeck) and ‘Skagg’s Bonanza’ (Citrus sinensis Osbeck) grafted on the rootstock trifoliate orange [Poncirus trifoliata (L.) Raf.], B at five levels was exogenously supplied to 1-year-old grafted plants of both cultivars under greenhouse conditions. Plants were grown in sand:perlite (1:1, v/v) medium and were irrigated every 2 days with half-strength Hoagland’s No. 2 nutrient solutions containing different B, 0.01, 0.05, 0.10, 0.25 and 2.50 mg l⁻¹ (0.25 and 2.50 mg l⁻¹ were considered as control and excess B treatment, respectively, and the other three B levels were considered as low B treatments). After treatments for 183 days, leaves (from basal, middle, upper parts of the shoots), stem of scion, stem of rootstock and root were separately sampled. Our results showed that plant growth (plant height, root volume and dry weights of various parts) was inhibited in response to low or excess B supplies in both cultivars. It was found that B concentrations in the upper leaves of both cultivars were substantially higher than those in the basal leaves when low concentrations (≤0.05 mg l⁻¹) of exogenous B were applied, suggesting that B was preferentially translocated to the upper-younger leaves to support their growth. Analysis of B distribution in different parts indicated that translocation of B from the root to the scion’s shoots (stems and leaves of scion) may be restricted upon exposure to low B conditions. When B was inadequately supplied, growth of ‘Skagg’s Bonanza’ was better than ‘Newhall’, implying that the former cultivar was more tolerant to low B status, which may be due to the higher efficiency of B translocation from the root to the scion’s shoots. However, when the plants were treated with excess B (2.50 mg l⁻¹), both cultivars showed a similar degree of B toxicity. The probability of scion–rootstock interactions in relation to the differential responses of growth and different efficiency of B translocation involved in the two orange cultivars following the long-term low B stress were discussed.     

Classification of rice germplasm: III. High-resolution fingerprinting of cytoplasmic genetic male-sterile (CMS) lines with AFLP

 The cytoplasmic genetic male-sterile (CMS) lines developed at the International Rice Research Institute are valuable in producing tropical rice hybrids. Efficient use of CMS lines in hybrid rice production will depend on their level of genetic diversity. Aside from morphological characterization, molecular analysis based on DNA markers can provide information on the genetic diversity of the germplasm. The Amplified Fragment Length Polymorphism (AFLP) technique was used to fingerprint 71 CMS lines and four rice cultivars, ‘IR64’, ‘Azucena’, ‘IR74’, and ‘FR13A’. Eleven primer pair combinations specific to the enzymes PstI and MseI were used to generate 530 AFLP markers, 176 of which were polymorphic. Each CMS line revealed a distinct fingerprint. The AFLP marker-based dendrogram depicted genetic variation among the CMS lines. The CMS lines developed in japonica background grouped with ‘Azucena’, a japonica cultivar. None of the CMS lines clustered with ‘FR13A’, a flood-tolerant traditional indica variety. ‘IR64’ was found to be distinct from the other indica CMS lines and clustered with lines developed in its background. The grouping of CMS lines into a few groups is useful for breeders in selecting genetically diverse CMS lines for hybrid rice production and in avoiding test crossing every CMS line empirically. This study demonstrated that AFLP is a powerful and reliable tool in determining the genetic relationships and in producing distinct fingerprints of rice cultivars. Received: 20 December 1996 / Accepted: 9 October 1997     

A consensus map of rye integrating mapping data from five mapping populations

A consensus map of rye (Secale cereale L.) was constructed using JoinMap 2.0 based on mapping data from five different mapping populations, including ‘UC90’ × ‘E-line’, ‘P87’ × ‘P105’, ‘I_0.1-line’ × ‘I_0.1-line’, ‘E-line’ × ‘R-line’, and ‘Ds2’ × ‘RxL10’. The integration of the five mapping populations resulted in a 779-cM map containing 501 markers with the number of markers per chromosome ranging from 57 on 1R to 86 on 4R. The linkage sizes ranged from 71.5 cM on 2R to 148.7 cM on 4R. A comparison of the individual maps to the consensus map revealed that the linear locus order was generally in good agreement between the various populations, but the 4R orientations were not consistent among the five individual maps. The 4R short arm and long arm assignments were switched between the two population maps involving the ‘E-line’ parent and the other three individual maps. Map comparisons also indicated that marker order variations exist among the five individual maps. However, the chromosome 5R showed very little marker order variation among the five maps. The consensus map not only integrated the linkage data from different maps, but also greatly increased the map resolution, thus, facilitating molecular breeding activities involving rye and triticale.     

Variation in performance on two grape cultivars within and among populations of grape Phylloxera from wild and cultivated habitats

When an indigenous insect becomes a pest, comparisons of performance of pest and non-pest populations on crop plants and of genetic variation in that performance may provide insight into the evolution of pest populations. To measure such genetic variation, 8–15 clones of the grape phylloxera (Daktulosphaira vitifoliae Fitch) were collected from wild grapevines in each of 3 geographically isolated sites (populations) and from commercial vineyards in northern California. A complete life table was made for clonal replicates from populations collected from wild grapevines on each of two commercial grape cultivars, the susceptibleVitis vinifera (L.) cultivar Cabernet Sauvignon, and the phylloxera-resistant rootstock ‘AxR # 1’. Variation in mean performance on these two hosts was partitioned among clones within collection sites and among sites. Performance measures included an individual analog to the intrinsic rate of increase (r), age at first oviposition, fecundity in the first ten days of reproduction, total fecundity, and longevity. The overall performance of phylloxera from the wild grapevines on the resistant cultivar AxR # 1 was greater than or equal to that on the susceptible cultivar Cabernet Sauvignon. There was significant variation among clones within populations from wild grapes in the rate of increase on ‘AxR # 1’ and marginally significant clonal variation in some of the component paramters. There was no significant variation among clones within populations on ‘Cabernet Sauvignon’ and no significant differences between populations on either crop in any trait. In a second experiment we compared the relative performance of 15–17 clones from wild grapevines and from commercial vineyards when reared on ‘Cabernet Sauvignon’ and ‘AxR # 1’. Phylloxera from commercial vineyards had much higher overall performance on ‘Cabernet Sauvignon’ than did phylloxera from the wild grapevines. Phylloxera from the commercial vineyard also had higher performance on ‘Cabernet Sauvignon’ than on ‘AxR′ 1’ but the performance of the phylloxera from wild and commercial grapes did not differ on ‘AxR # 1’. Our results show that there is genetic variation in traits related to performance on a resistant rootstock within these indigenous non-pest populations of phylloxera, but not among them. The pattern of performance of pest and non-pest populations on two commercial cultivars suggests that current levels of phylloxera performance on crop cultivars are the result of adaptation to those cultivars which has occurred while phylloxera has been associated with viticulture. Implications of these results for understanding the recent adaptation of phylloxera to ‘AxR # 1’ in California are also discussed.     

Parasitism ofLeptinotarsa decemlineata [Coleoptera: Chrysomelidae] byEdovum puttleri [Hymenoptera: Eulophidae] in different cultivars of eggplant

Experiments were conducted to quantify parasitism of Colorado potato beetle,Leptinotarsa decemlineata (Say), by the egg parasitoid,Edovum puttleri Grissell, on 3 different cultivars of eggplant,Solanum melongena L. Levels of parasitism were higher (P<0.05) on ‘Black Pride’ than on other cultivars. The percentage of egg masses that were parasitized was 1.2-fold higher (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’. The number of eggs per mass that were parasitized was 1.3- and 1.4- fold greater (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’, respectively. The percentage of eggs that were parasitized per mass and percentage of emerged adult parasitoids did not differ (P>0.05) among cultivars; between 2.1- to 2.6- fold more females than males emerged from eggs on all cultivars during the growing season.Edovum puttleri suppressed the 2nd generation ofL. decemlineata on ‘Black Pride’ and ‘Harris Special’, but did not suppress populations on ‘White’.      

The estimation of productivity and yield of linseed (<Emphasis Type="Italic">Linum usitatissimum</Emphasis> L.) using the growth analysis

In three year field experiments (2001 – 2003) the growth, yield and productivity of 8 flax cultivars were compared. Cultivars ‘AC Linora’, ‘Flanders’, ‘Linola™ 947’, ‘Norlin’ and ‘Omega’ were obtained from Canada, ‘Barbara’ and ‘Hungarian Gold’ from Hungary and ‘Opal’ from Poland. Apart from the estimation of the yield of aboveground parts dry matter and seed yield the determinations of the primary index value of growth analysis were done and on their basis the indices LAI, LAD, RGR, CGR and HI were calculated. The obtained yield results of the examined flax cultivars show significant genotypic — environmental relationships pertaining to the dynamics of dry matter accumulation and the amount of seed yield. Meteorological conditions in the successive years significantly influenced the particular phases of growth and development of cultivars and the factor which increased the amount of dry matter was the air temperature during the period of plant emergence — budding. During the vegetative season with a large amount of rainfall the average seed yield was about 40 % lower than compared with a year of average precipitation and a warm second part of the second period of flax vegetation. Among the analyzed cultivars a stable yield in all the years was characteristic for cultivars ‘Flanders’, ‘Barbara’ and ‘AC Linora’ (that cultivar, however, during a wet year yielded at a low level). The assimilation leaf surface of the linseed quickly increased during the period from budding to flowering and the accumulation of dry matter of the aboveground parts lasted up to the green maturity. In the successive years of the experiment there were observed significant (linear or logarithmic regressions) relationship between the yield of dry matter and the indices of growth analysis. The biggest values of the CGR indicator were observed for the period from budding to flowering. The maintaining of a high CGR value after plant flowering in the year with a favourable course of climatic parameters was beneficial for a better yield of all flax cultivars. The low values of the RGR index after flowering of cultivar ‘Hungarian Gold’ and ‘Opal’ strictly corresponded to their low yield of seed and straw biomass.     

Contributions of apoplasmic cadmium accumulation,antioxidative enzymes and induction of phytochelatins in cadmium tolerance of the cadmium-accumulating cultivar of black oat (<Emphasis Type="Italic">Avena strigosa</Emphasis> Schreb.)

The contributions of cadmium (Cd) accumulation in cell walls, antioxidative enzymes and induction of phytochelatins (PCs) to Cd tolerance were investigated in two distinctive genotypes of black oat (Avena strigosa Schreb.). One cultivar of black oat ‘New oat’ accumulated Cd in the leaves at the highest concentration compared to another black oat cultivar ‘Soil saver’ and other major graminaceous crops. The shoot:root Cd ratio also demonstrated that ‘New oat’ was the high Cd-accumulating cultivar, whereas ‘Soil saver’ was the low Cd-accumulating cultivar. Varied levels of Cd exposure demonstrated the strong Cd tolerance of ‘New oat’. By contrast, low Cd-accumulating cultivar ‘Soil saver’ suffered Cd toxicity such as growth defects and increased lipid peroxidation, even though it accumulated less Cd in shoots than ‘New oat’. Higher activities of ascorbate peroxidase (EC 1.11.1.11) and superoxide dismutase (EC 1. 15. 1. 1) were observed in the leaves of ‘New oat’ than in ‘Soil saver’. No advantage of ‘New oat’ in PCs induction was observed in comparison to Cd-sensitive cultivar ‘Soil saver’, although Cd exposure increased the concentration of total PCs in both cultivars. Higher and increased Cd accumulation in cell wall fraction was observed in shoots of ‘New oat’. On the other hand, in ‘Soil saver’, apoplasmic Cd accumulation showed saturation under higher Cd exposure. Overall, the present results suggest that cell wall Cd accumulation and antioxidative activities function in the tolerance against Cd stress possibly in combination with vacuolar Cd compartmentation.     

Peroxidase involvement in the defense response of red raspberry to Didymella applanata (Niessl/Sacc.)

Peroxidase activity of red raspberry canes was dependent on the cultivar and influenced the subsequent lignification. After inoculation with Didymella applanata, responsible for the spur blight cane disease, the activity of soluble cytoplasmic enzyme increased in the moderately resistant ‘Latham’ and susceptible ‘Malling Promise’, similarly for syringaldazine and guaiacol as hydrogen donors. Systemic induction found in ‘Latham’ was recognized as a symptom of defence mechanism responsible for fungal restriction. Locally enhanced peroxidase activity in the ‘M.Promise’ tissues was related to the local lignification and/or may be associated with the loss of cell integrity caused by pathogen penetration. Pathogen-induced changes of cell wall peroxidases were similar in both cultivars mentioned above. No influence of the infection was found in the high susceptible Zeva cultivar. Using native-PAGE analysis and horizontal starch electrophoresis of soluble fraction five constitutive acidic isoperoxidases were detected in ‘Latham’ and three in ‘M. Promise’. The infection process was accompanied by the appearance of two new anodic isoforms.     

The establishment of cell suspension cultures ofGladiolus that regenerate plants

Summary Inflorencence stalks from greenhouse-grownGladiolus plants of the cultivars ‘Blue Isle’ and ‘Hunting Song’ cultured on a Murashige and Skoog basal salts medium supplemented with 53.6 μM 1-napthaleneacetic acid formed a compact, not friable type of callus that regenerated plantlets. Cormel slices and intact plantlets of three cultivars (‘Peter Pears’, ‘Rosa Supreme’, ‘Jenny Lee’) propagated through tissue culture formed a friable type of callus when cultured on Murashige and Skoog basal salts medium supplemented with 2,4-dichlorophenoxyacetic acid. This friable callus readily formed a cell suspension when the callus was placed in a liquid medium. Plants were regenerated from two-month-old suspension cell cultures of the commercial cultivar ‘Peter Pears’ after the suspension cells had been cultured on solid medium.     

Life history ofAphis gossypii on cucumber: influence of temperature, host plant and parasitism

Life table data forAphis gossypii Glover (Homoptera: Aphididae), an important pest in glasshouse cucumber crops, were studied at 20, 25 and 30°C on two cucumber cultivars (Cucumis sativus L.) in controlled climate cabinets. The development time on the cucumber cv. ‘Sporu’ ranged from 4.8 days at 20°C to 3.2 days at 30°C. Immature mortality was approximately 20% and did not differ between temperatures. Most mortality occurred during the first instar. Reproduction periods did not differ among temperatures, but at 25 and 30°C more nymphs were produced (65.9 and 69.8 nymphs/♀, respectively) than at 20°C (59,9 nymphs/♀) because of a higher daily reproduction. Intrinsic rate of increase was greatest at 25°C (r _m =0.556 day⁻¹). At 20 and 30°C the intrinsic rate of increase was 0.426 and 0.510, respectively. On cv. ‘Aramon’, the development time ofA. gossypii was approximately 20% longer at all temperatures. Immature mortality did not differ between the two cultivars. The intrinsic rate of increase on cv. ‘Aramon’ was 15% smaller than on cv. ‘Sporu’. The use of cucumber cultivars partially resistant to aphids is discussed in relation to biological control of cotton aphid in glasshouses. Development time and immature mortality on leaves of the middle and upper leaf layer of glasshouse grown cucumber plants (cv. ‘Aramon’) were comparable to development in the controlled climate cabinets. On the lower leaves immature mortality was much higher (approximately 82%) than on leaves of the middle (24.0%) and upper leaf layer (24.5%). Reproduction was less on the lower leaf layer (45.9, 70.5 and 70.1 nymphs/♀ on leaves of the lower, middle and upper leaf layer, respectively). Aphids, successfully parasitized byAphidius colemani Viereck (Hymenoptera: Braconidae) only reproduced when they were parasitized after the third instar. Fecundity was 0.1 to 0.9 and 10.5 to 13.3 nymphs/♀ for aphids parasitized in the fourth instar or as adults, respectively. Reproduction of aphids that were stung but survived the attack was lower than for aphids not stung. Average longevity of these aphids was equal to the longevity of aphids not stung byA. colemani.     

Response of durum wheat cultivars to immature embryo culture,callus induction and in vitro salt stress

Response of twenty eight cultivars of durum wheat (Triticum turgidum var. durum) to immature embryo culture, callus production and in vitro salt tolerance was evaluated. For assessment of cultivars to salt tolerance, growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 and 2.1% w/v) added to the culture medium during two subsequent subcultures (4 weeks each). Comparison of cultivars for callus induction from immature embryo was based on callus induction frequency and fresh weight growth of callus (FWG). While, for salt tolerance, the relative fresh weight growth (RFWG) and necrosis percent of callus were used. There were significant differences among cultivars for potential of regeneration from immature embryo, and ‘Shahivandi’ a native durum wheat cultivar originating from western Iran was superior among the cultivars tested. The FWG distinguished cultivars more than callus induction frequency did for callus induction evaluation. Hence, a range of FWG from 1.23 to 14.65 g was observed in ‘Mexical-75’ and ‘Omrabi-5’ cultivars, respectively. Growing calli derived from cultivars ‘PI 40100’ and ‘Dipper-6’ showed superiority for tolerating salinity under in vitro conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Local and systemic protection of poinsettia (Euphorbia pulcherrima Willd.) against Botrytis cinerea Pers. induced by benzothiadiazole

Benzothiadiazole (BTH) was found to be highly effective in increasing resistance of two poinsettia cultivars — ‘Coco White’ and ‘Malibu Red’, moderately susceptible to the fungus Botrytis cinerea. BTH applied at a concentration of 0.3 mM on the discs cut out from the leaves of these poinsettia cultivars reduced disease symptoms by more than 60 % in comparison to the control discs treated with water and exposed to infection. It was also observed that the applied inducer at a concentration of 0.03 and 0.3 mM had a favourable influence on the increase of poinsettia systemic resistance of SAR type (systemic acquired resistance). The effectiveness of BTH was much less when disease development was examined on detached leaves (a 20 % reduction of lesion area) in comparison with a pronounced inhibition of grey mould development on intact leaves of previously induced plants (a 80 % protection of intact plants). Benzothiadiazole in the concentration range from 0.03 to 1.4 mM added to in vitro agar medium was not found to have an inhibitory influence on Botrytis cinerea mycelium growth and sporulation.     

Taxonomic discrimination of flowering plants by multivariate analysis of Fourier transform infrared spectroscopy data

Fourier transform infrared spectroscopy (FTIR) provides biochemical profiles containing overlapping signals from a majority of the compounds that are present when whole cells are analyzed. Leaf samples of seven higher plant species and varieties were subjected to FTIR to determine whether plants can be discriminated phylogenetically on the basis of biochemical profiles. A hierarchical dendrogram based on principal component analysis (PCA) of FTIR data showed relationships between plants that were in agreement with known plant taxonomy. Genetic programming (GP) analysis determined the top three to five biomarkers from FTIR data that discriminated plants at each hierarchical level of the dendrogram. Most biomarkers determined by GP analysis at each hierarchical level were specific to the carbohydrate fingerprint region (1,200–800 cm^–1) of the FTIR spectrum. Our results indicate that differences in cell-wall composition and structure can provide the basis for chemotaxonomy of flowering plants.Abbreviations FTIR Fourier transform infrared spectroscopy - GP Genetic programming - PCA Principal component analysis - PyMS Pyrolysis mass spectrometry