Bacteria associated with hazelnut (Corylus avellana L.) decline are of two groups: Pseudomonas avellanae and strains resembling P. syringae pv. syringae

A total of 118 fluorescent pseudomonads associated with hazelnut decline, which has been occurring for many years in different areas of northern Greece and Italy, were assessed by performing a repetitive PCR analysis with enterobacterial repetitive intergenic consensus, box element, and repetive extragenic palindromic primer sets, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell protein extracts, a carbon compound utilization analysis, and an analysis to determine the presence of the syrB gene. A subset of 53 strains was also characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA) by using nine restriction endonucleases. The virulence of 40 representative strains was assessed by using serial doses. The pathogenic specificities of the strains were also verified. ARDRA carried out with HinfI revealed two main groups of strains, groups A and B, which exhibited a level of similarity of 57%. The other eight restriction endonucleases used did not separate the strains. In addition, a cluster analysis performed by the unweighted pair group method using arithmetic averages after repetitive PCR and SDS-PAGE of protein extracts also revealed the same two groups. Furthermore, the differential utilization of some carbon compounds made it possible to differentiate the groups. Virulence assessment clearly indicated that the group A strains are very virulent, whereas the group B strains proved to be mildly virulent for hazelnut. Group A included the strains isolated in northern Greece and central Italy (i.e., the province of Viterbo); these strains do not have the syrB gene, are pathogenically restricted to Corylus avellana, and belong to Pseudomonas avellanae. Group B includes the other strains obtained from hazelnut cultivated in Piedmont, Campania, Latium, Sicily, and Sardinia. They represent a distinct taxon closely related to Pseudomonas syringae pv. syringae.     

DNA typing and genetic relations among European hazelnut (Corylus avellana L.) cultivars using microsatellite markers.

In this work, 78 hazelnut (Corylus avellana L.) cultivars from various germplasm repositories were studied at 16 simple sequence repeat (SSR) loci in order to identify the genotypes and investigate their genetic relations. Polymorphism at SSR loci was evaluated on the basis of number of alleles (mean: 9.4), expected heterozygosity (mean: 0.78), and power of discrimination (mean: 0.91). Several synonyms reported in the literature were confirmed, and new cases of synonymy were identified. The parentage of North American cultivars 'Butler', 'Ennis', and 'Royal', the French selection 'Fercoril-Corabel', and 'Impératrice Eugenie' was investigated on the basis of the alleles present at 16 loci and analysis at 8 additional loci. A dendrogram generated from cluster analysis using the unweighted pair group method with arithmetic mean grouped cultivars according to their pedigrees or geographical origins. There was an evident differentiation of the northern European cultivars from the southern European ones and from the Turkish cultivars. The latter clustered close to but separate from the Italian and Spanish clusters. It is very likely that exchanges of cultivars occurred between the central and western Mediterranean basin as a result of human migration and trade. A database containing the SSR profiles of the most important hazelnut cultivars will be useful for identification of cultivars and synonyms, legal protection, and parentage analysis.     

Genetic relationship among wild,landraces and cultivars of hazelnut (Corylus avellana) from Portugal revealed through ISSR and AFLP markers

The genus Corylus, a member of the birch family Betulaceae, includes several species that are widely distributed throughout temperate regions of the Northern Hemisphere. This study assesses the genetic diversity in 26 international cultivars and 32 accessions of Corylus avellana L. from Portugal: 13 wild genotypes and 19 landraces. The genetic relationships among the 58 hazelnuts (Corylus avellana L.) were analyzed using inter simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP) markers. Eighteen ISSR primers and seven AFLP primer pairs generated a total of 570 unambiguous and repeatable bands, respectively, from which 541 (95.03 %) were polymorphic for both markers. Genetic similarity index values ranged from 0.239 for wild types and cultivars to 0.143 for landraces and wild types. The genetic relationships were presented as a Neighbor-Joining method dendrogram and a two-dimensional principal coordinate analysis (PCoA) plot. The Neighbor-Joining dendrogram showed three main clusters, and the PCoA analysis has shown to be congruent with the hierarchical analysis. Bayesian analysis clustered all individuals into three groups showing a good separation among wild genotypes, landraces and cultivars. The genetic diversity found on wild genotypes and Portuguese landraces may provide relevant information for the diversity conservation and it will be useful in breeding programs and to identify local selections for preservation.     

In vitro establishment of a cycloclonal chain from nodal segments and apical buds of adult hazel (Corylus avellana L.)

Apical buds (0.5 cm) and nodal shoot segments (1.5 cm) excised from: A) field-grown branches, B) newly developed shoots from the forced outgrowth of axillary buds on A branches, C) newly developed shoots from the forced outgrowth of axillary buds on A branches submitted to cold storage were used as primary explants. Results indicate that three months cold storage greatly increases morphogenic capacity and reduces contamination and oxidation of tissues. Consequently, a multiplying chain could be easily established by culturing the tissues on a modified Murashige & Skoog (1962) medium plus 6-benzyl-aminopurine 5 mg l^-1, indole-3-acetic acid 0.01 mg l^-1 and gibberellic acid 0.1 mg l^-1. During the initiation and proliferation phases, both the proliferation and the elongation rate were significantly increased when a double-phase culture system (Viseur 1987) was used, giving rise to a higher microplant production than the one obtained using previously described methods. Plant regeneration was achieved by immersing the single microshoot's basal end in an IBA (0.1–1 mg ml^-1) solution for 10 s followed by a 20-day culture on a 1/2 MS2 medium.Abbreviations BAP 6-benzylaminopurine - GA₃ gibberellic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2ip 2-isopentenyladenine - MS1 and MS2 modified Murashige & Skoog media - NAA 2-maphtaleneacetic acid     

Behavioural response of green peach aphid Myzus persicae (Sulzer) to volatiles from different rosemary (Rosmarinus officinalis L.) clones

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Phosphorus efficiency and phosphorus remobilization in two sorghum (Sorghum bicolor (L.) Moench) cultivars

With two sorghum cultivars differing in P efficiency a P uptake experiment (³²P/³³P labelling) was carried out followed by a period of P deficiency. The tendency of the total P distribution and redistribution pattern was rather similar in both sorghum cultivars. Although in the cultivar with a greater P absorbing capacity per unit root weight a higher proportion of the P was found in the inorganic P soluble fraction this is not necessarily an indication of a higher vacuolar affinity for P. Under P deficiency in both cultivars a rapid decrease of the TCA soluble P fraction in the leaves was observed. Before complete exhaustion of this fraction the TCA insoluble P fraction was also markedly reduced. In the roots the total P content was maintained fairly constant with a distinct shift in favour of the insoluble fraction occurring during the period of P deficiency. It is assumed that in the P efficient sorghum cultivar producing more dry matter per increment of P absorbed, rather inherent growth promoting factors contribute to the intraspecific P efficiency by a stimulation of the intensity of P redistribution and thus compensate for the lower P absorbing capacity of its roots.     

Shoot bud regeneration from different explants of Bacopa monniera (L.) Wettst. by trimethoprim and bavistin

A mass in vitro propagation system devoid of growth regulators for Bacopa monniera (L.) Wettst., a traditional Indian medicinal plant, has been developed. Direct shoot bud regeneration was induced by culturing internode and leaf explants on Murashige and Skoog's (MS) medium supplemented with an antibiotic (trimethoprim) or a fungicide (bavistin). Bavistin showed a marked cytokinin-like activity, as evident from high number of shoot buds induced in node, internode and leaf explants. Optimum adventitious shoot buds induction occurred at 300 mg/l bavistin from internode explants. In vitro regenerated shoots were elongated and rooted before transferred to field with 85% survival. The regeneration protocol developed in this study illustrates the usefulness of additives for mass propagation and germplasm conservation of B. monniera.Authors Vaibhav Tiwari and Kavindra Nath Tiwari contributed equally to this work     

不同温度敏感性棉花纤维发育相关酶活性变化对低温的响应

选用纤维比强度形成存在温度敏感性差异的两个棉花品种（科棉1号：温度弱敏感型品种,苏棉15：温度敏感型品种）为材料,于2006—2007年在江苏南京设置大田分期播种试验,使棉纤维发育处于不同的温度条件,研究低温对棉纤维发育相关酶（蔗糖酶、蔗糖合成酶、磷酸蔗糖合成酶、β-1,3-葡聚糖酶）活性及相应基因表达的影响.结果表明：由晚播造成的低温（棉纤维发育期日均最低温分别为21.1、20.5和18.1 ℃）影响了纤维发育相关酶的活性变化,从而影响了棉纤维素累积和纤维比强度的形成.低温提高了纤维中蔗糖酶和β-1,3-葡聚糖酶的活性,降低了蔗糖合成酶和磷酸蔗糖合成酶的活性.低温使Expansin、蔗糖合成酶基因的高表达时间延长,β-1,3-葡聚糖酶基因的表达峰值出现时间延迟,且表达量降低.两个棉花品种的纤维素合成相关酶对低温的响应存在差异,温度敏感型品种（苏棉15）的酶活性的变化幅度明显高于温度弱敏感型品种（科棉1号）, 可能是导致不同棉花品种纤维比强度形成存在温度敏感性差异的主要原因.     

Population fluctuations of cabbage aphid,Brevicoryne brassicae (L.) (Hom.: Aphididae) and its natural parasitism rate on different canola cultivars

The cabbage aphid, Brevicoryne brassicae is one of the most destructive pests in Cruciferaceae or Brassicaceae plant family around the world. According to this pest rapid resistance to insecticide, using the resistant cultivars should be evaluated. In the present study, the different canola cultivars resistance against the cabbage aphid and the population fluctuations in canola fields and also the natural parasitism are evaluated in Shahre-rey region. To evaluate the population fluctuations and its natural parasitism on the RGS003, SLMOO46, Karag2, Licord, Sarigol, Opera, Ocapi and Talaei canola cultivars were cultivated in four replications using the complete randomised block design. The population fluctuations studies showed that the pest is active during the canola growth period in studied region, but the peak of population and damage is found in 6 May month. The results showed that natural parasitism percentage of cabbage aphid on different canola cultivars has not significant difference, but the parasitism amount in different sampling dates was significantly different, so that the natural parasitism maximum observed in date 29 April. These results showed that the different canola cultivars have significant effects on cabbage aphid and parasitoids activity amount. Using the present results, the recognised cultivars in integrated pest management programmes can be used to grow the laboratory aphids as the parasitoids hosts.     

Development, characterization, segregation, and mapping of microsatellite markers for European hazelnut (Corylus avellana L.) from enriched genomic libraries and usefulness in genetic diversity studies

Eighty-six new microsatellite loci were developed for European hazelnut (Corylus avellana L.) by screening two genomic libraries enriched for dinucleotide repeats. The loci, 73 developed from a GA-enriched library and 13 from a CA-enriched library, showed a high level of polymorphism in 50 accessions. The number of alleles per locus ranged from five to 21, with a mean of 10.55. Mean values for expected heterozygosity, observed heterozygosity, and polymorphism information content were high, averaging 0.76, 0.69, and 0.73, respectively. In a mapping population, loci segregated 1:1, 1:2:1, and 1:1:1:1. Segregation distortion and null alleles were observed at some loci. Eighty-one of the 86 loci were assigned to linkage groups. A neighbor-joining dendrogram reflected great diversity among the 50 accessions and showed clustering by geographic origin.     

Genetic linkage maps of two apricot cultivars ( Prunus armeniaca L.), and mapping of PPV (sharka) resistance

Genetic linkage maps for two apricot cultivars have been constructed using AFLP, RAPD, RFLP and SSR markers in 81 F1 individuals from the cross 'Goldrich' x 'Valenciano'. This family segregated for resistance to 'plum pox virus' (PPV), the most-important virus affecting Prunus species. Of the 160 RAPD arbitrary primers screened a total of 44 were selected. Sixty one polymorphic RAPD markers were scored on the mapping population: 30 heterozygous in 'Goldrich', 19 heterozygous in 'Valenciano', segregating 1:1, and 12 markers heterozygous in both parents, segregating 3:1. A total of 33 and 19 RAPD markers were mapped on the 'Goldrich' and 'Valenciano' maps respectively. Forteen primer combinations were used for AFLPs and all of them detected polymorphism. Ninety five markers segregating 1:1 were identified, of which 62 were heterozygous in the female parent 'Goldrich' and 33 in the male parent 'Valenciano'. Forty five markers were present in both parents and segregated 3:1. A total of 82 and 48 AFLP markers were mapped on the 'Goldrich' and 'Valenciano' maps. Twelve RFLPs probes were screened in the population, resulting in five loci segregating in the family, one locus heterozygous for 'Valenciano' and four heterozygous for both, segregating 1:2:1. Of the 45 SSRs screened 17 segregated in the mapping family, resulting in seven loci heterozygous for the maternal parent and ten heterozygous for both, segregating 1:2:1 or 1:1:1:1. A total of 16 and 13 co-dominant markers were mapped in the female and male parent maps respectively. A total of 132 markers were placed into eight linkage groups on the 'Goldrich' map, defining 511 cM of the total map-length. The average distance between adjacent markers was 3.9 cM. A total of 80 markers were placed into seven linkage groups on the 'Valenciano' map, defining 467.2 cM of the total map-distance, with an average interval of 5.8 cM between adjacent markers. Thirty six marker loci heterozygous in both parents revealed straightforward homologies between five linkage groups in both maps. The sharka resistance trait mapped on linkage group 2. The region containing sharka resistance is flanked by two co-dominant markers that will be used for targeted SSR development employing a recently constructed complete apricot BAC library. SSRs tightly linked to sharka resistance will facilitate MAS in breeding for resistance in apricot.     

Effects of phosphate on arsenate and arsenite sensitivity in two rice (Oryza sativa L.) cultivars of different sensitivity

Arsenate and arsenite sensitivity and arsenate influx tests were conducted for two rice cultivars of different arsenic sensitivity, Azucena and Bala. These were to establish if the mechanism of reduced arsenic sensitivity is achieved through an altered phosphate uptake system, as shown for Holcus lanatus. High phosphate treatments (≥50 μM) provided protection against both arsenate and arsenite. Unlike the H. lanatus tolerance mechanism, in the less sensitive cultivar Bala, arsenate influx did not decrease with phosphate treatment and phosphate transporters appeared to be constitutively upregulated; V_max for arsenate influx remain similar when Bala was grown in the presence or absence of phosphate (V_max - 0.90 and 0.63 nmol g⁻¹ f.wt min⁻¹ respectively). Although mean K_m appear different, Bala did not show lower affinity to arsenate than Azucena in the absence of phosphate (K_m - Azucena, 0.30 mM and Bala, 0.18), while in phosphate treatment, Bala arsenate affinity was half that observed for Azucena (K_m - Azucena, 0.14 and Bala, 0.36 mM). These were low compared to a 4 and 6 fold decrease seen for similar studies on H. lanatus in the absence and presence of phosphate. Phosphate-induced arsenic protection was observed but the mechanism does not resemble that of H. lanatus. Alternative mechanisms were discussed.     

Jasmonate effects on in vitro tuberization and tuber bulking in two potato cultivars (Solanum tuberosum L.) under different media and photoperiod conditions

Summary Jasmonic acid (JA) effects on in vitro tuberization of potato nodal explants cvs. Sangre and Russet Burbank were tested under liquid and solid media conditions and 0,8, and 16h photoperiod. Explants taken from stock plants grown on 2.5μM JA-supplemented medium tuberized first, particularly in darkness. The most pronounced benefits of the JA pretreatment were recorded under 16h photoperiod, which is known to inhibit tuberization. Cultivar Sangre benefited from the JA preconditioning of stock plants more than Russet Burbank. Russet Burbank required the JA supplement in tuberization media to reach the same degree of stimulation. Overall, microtubers produced either from JA preconditioned stock plants or on the JA-containing tuberization media were more uniform and larger than from other treatments. Eight hours photoperiod was by far the best treatment for the production of high-quality uniform microtubers. JA conditioning of stock plants prior to taking explants for tuberization is being proposed as a treatment enhancing the quality of microtubers.     

Effect of different levels of mineral nitrogen on nodulation and N2 fixation of two cultivars of common bean (Phaseolus vulgaris L.)

An experiment was conducted under greenhouse conditions to evaluate the effect of mineral nitrogen on N₂ fixation of two cultivars of Phaseolus vulgaris L., Puebla 152 and Negro Argel. Nitrogen application was 0, 2.5, 12.5 and 25 mg N Kg^–1 of a vermiculite-sand-mixture at planting time. Shoot and root growth were elevated by nitrogen application at all growth stages. During vegetative growth (V 5) nodule dry weight and nitrogenase activity (acetylene reducing activity) per plant were reduced by nitrogen supply in both cultivars, but less in Negro Argel than in Puebla 152. At later stages nodulation in nitrogen-treated Puebla 152 did not differ from that in non-treated plants, whereas increased nodule number was found in Negro Argel at high nitrogen levels. The influence of mineral N on the total amount of nitrogen fixed in the two bean cultivars was only slightly different.     

Root morphology ion absorption and antioxidative defense system of two Chinese cabbage cultivars (Brassica rapa L.) reveal the different adaptation mechanisms to salt and alkali stress

Salt stress and alkali stress are major factors that affect the growth and production of Chinese cabbage. To explore their tolerant mechanism to salt and alkali stress, three salinity levels (0, 50, 100 mmol/L NaCl) and three different pH levels (pH6.5, pH7.5, pH8.5) were interactively applied on Qinghua (salt-tolerant–alkali-sensitive) and Biyu (salt-sensitive–alkali-tolerant) cultivars; the root morphology, ion content and antioxidant enzymes were determined. The results showed that the root morphology and root water content of Qinghua under S₀pH_7.5 and S₀pH_8.5 were seriously affected, and the content of H₂O₂ and MDA increased by 143%, 190% and 234%, 294%, respectively, compared with S₀pH_6.5; when Biyu was under S₅₀pH_6.5 and S₁₀₀pH_6.5 stress, the content of H₂O₂ and MDA increase to 152%, 208% and to 240%, 263%, respectively, but the activities and genes expression of SOD, POD, CAT, AAO, APX, DHAR and MDHAR did not change. The root and the contents of H₂O₂ and MDA were not affected when Qinghua was treated with salt and Biyu was treated with alkali, but the activities of the antioxidant enzymes increased to 150–200%, and their relative expression was overexpressed and 2.5–3.5-fold of the S₀pH6.5. The increase of Na⁺ in Qinghua was limited under salt stress, Mg²⁺ in Biyu increased significantly under alkali stress. These all indicated that the adaptability of roots could reflect the degree of tolerance; Chinese cabbage with high salt and alkali tolerance enhanced the regulation of their absorption of ions and increased the relative expression and activities of related antioxidant enzymes.

     

Effect of different rootstocks on PAL activity and phenolic compounds in flowers, leaves, hulls and kernels of three pistachio (Pistacia vera L.) cultivars

Phenylalanine ammonia-lyase (PAL) is a biochemical marker of environmental stress and plays a pivotal role in phenolic synthesis. Lower ROS levels and oxidative damage were observed in grafted plants; moreover, the rootstocks have a profound influence on the biochemical composition, especially of phenolic compounds. Regarding the importance of the effect rootstocks have on scion in pistachio trees, this study was carried out to assess and compare three pistachio cultivars (Ahmadaghaii, Ohadi and Kallehghuchi) on four rootstocks (Mutica, Ahli, Sarakhs and Atlantica). PAL activity, phenolic compounds, and flavonoid and anthocyanin contents in leaves, flowers and fruits were measured for the selection of the most suitable and compatible rootstock/scion resistant to environmental stresses. The results showed that PAL activity was different among the cultivars and organs. A positive correlation was observed between PAL activity and phenolic compounds in the leaves and flowers of Mutica-Ahmadaghaii, suggesting that it was more resistant than the others to environmental stresses. PAL activity and total phenolics in pistachio fruits suffered a decrease when the maturation processes began. The hulls of the pistachio fruits contained high levels of phenolic compounds, especially in Mutica-Ahmadaghaii, suggesting its function as a protective layer and a defense chemical against ultraviolet radiation and pathogens. Our results indicated the presence of a number of bioactive compounds in kernels with the highest amount belonging to Mutica-Ahmadaghaii. Therefore, we concluded that pistachio rootstocks mighy affect the antioxidant compounds in kernels.     

Behavioral responses of leaves and vascular cambium of Prosopis cineraria (L.) Druce to different regimes of coal-smoke pollution

Abstract

The foliar and cambial responses of Prosopis cineraria to five different coal-smoke regimes in Delhi, India, were studied using the monthly collections of leaves and cambial blocks as well as the data on SO₂, NO₂ and particulate concentrations from each of the five study sites. Coal-smoke inhibited pigment concentration, NR activity and sugar content and promoted stomatal index and the nitrate and sulfur contents. Stomatal conductance was low, leading to a drop in the net photosynthetic rate. Cambial activity started quite late and the annual increment of wood was reduced despite a prolonged active phase, possibly due to a distinctly retarded rate of cambial cell division. Vessel proportion in the wood increased but the size of vessel elements and fibers decreased. Such studies may help in identifying trees suitable for cultivation in the pollution-affected areas.