First Report of Meloidogyne graminicola Infecting Banana in China

Bananas (Musa spp.) are one of world's most popular fruits, and China is the third largest banana-producing country in the world. Root-knot nematodes, Meloidogyne spp., are common pests of banana worldwide, but damage to this crop caused by M. graminicola has not been reported up to now. During a survey of root-knot nematode species infecting banana in Fujian Province, China, swollen, galled primary and secondary root samples of Musa nana cv. Tianbao (AAA) were collected from two commercial fields in Nanjing County in May 2013. The affected plants did not exhibit obvious above-ground symptoms. Seriously infected roots were malformed and dehiscent, with the tissue discolored and rotting. Examination of symptomatic roots revealed one to several females of Meloidogyne sp. within each gall, with egg masses that were often completely embedded within the gall without protruding through the root surface, and with second-stage juveniles (J2) hatched inside the galls. Population densities of this nematode ranged from 452 to 2,056 eggs and J2 per 5 g of fresh roots. Males were rarely observed. Morphological measurements of 25 females and 20 J2 matched the original description of M. graminicola (1). The perineal patterns of females were dorsoventrally ovoid, with low to moderately high and round dorsal arches and lacking obvious lateral lines; striae were smooth and some were broken by a few obvious irregular, zig-zag striae in the dorsal part of the pattern; phasmids were close together (13.1 to 19.7 μm). The J2 had long tapered tails (63.4 to 75.5 μm), with long narrow hyalines (13.1 to 19.9 μm) and marked clavate termini. DNA was extracted from one mature female. The ITS1-5.8S-ITS2 rDNA region was amplified with V5367/26S (TTGATTACGTCCCTGCCCTTT/TTTCACTCGCCGTTACTAAGG) (2) and the COII and IRNA mtDNA genes were amplified with C2F3/MRH106 (GGTCAATG TTCAGAAATTTGTGG/AATTTCTAAAGACTTTTCTTAGT) (3) and then sequenced. The sequences were subjected to a database search using BLAST to verify the identity. Sequences from the ITS region were 788 bp (GenBank Accession Nos. KM111531 and KM236560) and were 96.8 to 99.1% identical to the known sequences of M. graminicola in Genbank. Sequences from the mtDNA were 666 bp (KM111533 and KM236559) and showed 99.1 to 99.4% homology with the known sequences of M. graminicola (KJ139963 and HG529223). In glasshouse tests, banana plantlets (M. nana cv. Tianbao) about 20 cm high were transplanted in 25-cm-diameter pots and inoculated with 5,000 J2 of each collected population of M. graminicola replicated six times; a noninoculated control was included. After 15 weeks, all inoculated plants were stunted and chlorotic. Galling symptoms on roots were similar to those in the field, and dissection of galled root tissue revealed that different life stages of the nematode were present, with population densities ranging from 1,238 to 6,562 eggs and J2 per 5 g of fresh roots. The noninoculated control plants grew well and had no galling symptoms on the roots. These results confirmed the nematodes' pathogenicity on banana. On the basis of these results, the root-knot nematodes isolated from banana in Nanjing County were confirmed as M. graminicola. To our knowledge, this is the first report of a natural infection of banana with M. graminicola. References: (1) A.M. Golden and W. Birchfield. Plant Dis. Rep. 52:423, 1968. (2) T. C. Vrain et al. Fund. Appl. Nematol. 15:565, 1992. (3) J. Xu et al. Eur. J. Plant Pathol. 110:309, 2004.

First Report of Meloidogyne enterolobii on Carrot in China

Carrot (Daucus carota var. sativus) is one of the 10 most economically important vegetable crops in the world. Recently, stunted and yellowing carrots grown on sandy soil in several commercial fields were observed in Dongshan County, Fujian Province, China. Many round to irregular shaped lumps and swellings were present on the surface of tap and fibrous roots, often with secondary roots emerging from the galls on taproots. Severe infection caused short, stubby, forked taproots leading to losses in quality and marketability. Meloidogyne sp. females and egg masses were dissected from the galls. The perineal patterns from 20 females were oval shaped with moderate to high dorsal arches and mostly lacking obvious lateral lines. The second-stage juvenile mean body length (n = 20) was 416 (390 to 461) μm; lateral lips were large and triangular in face view; tail was thin and length was averaged 56.1 (49.8 to 62.1) μm, with a broad, bluntly rounded tip. These morphological characteristics matched the original description of M. enterolobii (5). Species identity was further explored by sequencing the mitochondrial DNA (mtDNA) region between COII and the lRNA genes using primers C2F3/MRH106 (GGTCAATGTTCAGAAATTTGTGG/AATTTCTAAAGACTTTTCTTA GT) (4). A DNA fragment of ~840 bp was obtained and the sequence (GenBank Accession No. KJ146864) was compared with those in GenBank using BLAST and was 100% identical to the sequences of M. enterolobii and M. mayaguensis, a synonym of M. enterolobii (4). Part of the rDNA spanning ITS1, 5.8S gene, ITS2 was amplified with primers V5367/26S (TTGATTACGTCCCTGCCCTTT/TTTCACTCGCCGTTACTAAGG) (3), and the sequence obtained (KJ146863) was 99 to 100% identical to sequences of M. enterolobii (KF418369.1, KF418370.1, JX024149.1, and JQ082448.1). For further confirmation, M. enterolobii specific primers Me-F/Me-R (AACTTTTGTGAAAGTGCCGCTG/TCAGTTCAGGCAGGATCAACC) (2) were used for amplification of the rDNA-IGS2 sequences of eight populations of the nematode from three localities. A 200-bp amplification product was produced by each population, whereas no product was amplified from control populations of M. incognita or M. javanica. A single product of ~320 bp was obtained using primers 63VNL/63VTH (GAAATTGCTTTATTGTTACTAAG/TAGCCACAGCAAAATAGTTTTC ) (1) from the mtDNA 63-bp repeat region for these populations, and the sequence (KJ146861) showed 100% identity with sequences of M. enterolobii (AJ421395.1, JF309159.1, and JF309160.1). Therefore, the population of Meloidogyne sp. on carrot was confirmed to be M. enterolobii. This nematode has been reported to infect more than 20 plant species belonging to seven families, including Annonaceae, Cucurbitaceae, Convolvulaceae, Fabaceae, Marantaceae, Myrtaceae, and Solanaceae in China. To our knowledge, this is the first report of infection of carrot by M. enterolobii and the first record of M. enterolobii parasitizing a plant in the family Apiaceae in China. M. enterolobii has been reported in Guangdong and Hainan provinces, China. This is the first report of M. enterolobii in Fujian Province, in southeast China. References: (1) V. C. Blok et al. Nematology 4:773, 2002. (2) H. Long et al. Acta Phytopathol. Sin. 36:109, 2006. (3) T. C. Vrain et al. Fundam. Appl. Nematol. 15:565, 1992. (4) J. Xu et al. Eur. J. Plant Pathol. 110:309, 2004. (5) B. Yang and J. D. Eisenback. J. Nematol. 15:381, 1983.

Terminal arbor degeneration--a novel lesion produced by the antineoplastic agent paclitaxel

The antineoplastic agent paclitaxel causes a dose-limiting distal, symmetrical, sensory peripheral neuropathy that is often accompanied by a neuropathic pain syndrome. In a low-dose model of paclitaxel-evoked painful peripheral neuropathy in the rat, we have shown that the drug causes degeneration of intraepidermal nerve fibers (IENFs), i.e. the fibers which give rise to the sensory afferent's terminal receptor arbor. However, we did not find any evidence for axonal degeneration in samples taken at the mid-nerve level. Here we aimed to determine whether the absence of degenerating peripheral nerve axons was due to sampling a level that was too proximal. We used electron microscopy to study the distal-most branches of the nerves innervating the hind paw glabrous skin of normal and paclitaxel-treated rats. We confirmed that we sampled at a time when IENF degeneration was prominent. Because degeneration might be easier to detect with higher paclitaxel doses, we examined a four-fold cumulative dose range (8-32 mg/kg). We found no evidence of degeneration in the superficial subepidermal axon bundles (sSAB) that are located just a few microns below the epidermal basal lamina. Specifically, for all three dose groups there was no change in the number of sSAB per millimeter of epidermal border, no change in the number of axons per sSAB and no change in the diameter of sSAB axons. We conclude that paclitaxel produces a novel type of lesion that is restricted to the afferent axon's terminal arbor; we name this lesion 'terminal arbor degeneration'.

Enhancement of phosphor efficiency via composition modification

The luminescence efficiency of Mn4+-doped CaAl12O19 (Mn:CAO) is significantly improved by composition modification. The leading mechanism that quenches the Mn4+ photoluminescence is the formation of Mn4+ pairs in the lattice of CaAl12O19 (CAO) with interstitial O2- for charge compensation. Mixing Mg2+ ions into the CAO lattice may form Mn4+-Mg2+ pairs and reduce the number of Mn4+ pairs, thus enhancing the Mn4+ luminescence efficiency by more than three times. It is shown that the presence of Mg2+ leads to formation of additional phases that also affect the optical properties of Mn4+.

Systematic Behavior of Charge-Transfer Transitions and Energy Level Variation in Soft Donor Complexes of the Trivalent Lanthanides

The systematic behavior of the charge-transfer (CT) energies in mixed 2,2'-bipyridyl (bipy), N,N-diethyldithiocarbamate (Et2dtc-) complexes of the trivalent lanthanides, Ln(Et2dtc)3(bipy), is investigated to understand the electronic structure of f-element complexes containing soft donor ligands. The energies of ligand to Ln3+ CT are extremely low in this system, an effect attributed to the presence of the soft donor ligands. The lowest CT energy level for the Sm3+, Eu3+, and Yb3+ complexes falls into the visible range. In Eu(Et2dtc)(bipy), the Eu3+ ion becomes nonluminescent because the CT energy stretches below the metastable 5D0 electronic state, whereas luminescence from the CT state and the 4f13 (2)F(5/2) state are observed in the Yb compound. The variation in the energy of the lowest level CT transition for the entire Ln(Et2dtc)3(bipy) series has been evaluated using the experimentally determined CT levels of the Sm3+, Eu3+, and Yb3+ compounds based on the systematic behavior of the lanthanides, which is invariant with respect to the type of ligand. The energy difference between the ground electronic states of the lanthanide ions and the ligand-centered valence band may also be calculated from these results.

Analysis of Energy Level Structure and Excited-State Dynamics in a Sm3+ Complex with Soft-Donor Ligands: Sm(Et2Dtc)3(bipy)

Using both laser-excited fluorescence and optical absorption methods, we have determined 57 crystal-field (CF) energy levels of Sm 3+ in crystals of Sm(Et2Dtc)3(bipy). The analysis of the energy levels is based on a model Hamiltonian consisting of both free-ion and CF terms. The CF modeling of the experimental energy levels yielded physically reasonable Hamiltonian parameters with a final rms deviation of 17.3 cm(-1). In comparison with Sm 3+ in other hosts, the CF splitting of Sm 3+ in the lattice of Sm(Et2Dtc)3(bipy) is rather weak. The observed fluorescence decay of the 4G(5/2) manifold is single-exponential, with a lifetime of 24.5 mus, indicating only one site of Sm3+ in the lattice. According to the Judd-Ofelt theory, values of three intensity parameters were obtained (Omega(2,4,6) = 1.57, 2.65, and 3.65, in units of 10(-20) cm(-1)). The calculated branching ratios for transitions from the 4G(5/2) manifold are in agreement with experimental values. The calculated radiative lifetime of the 4G(5/2) manifold is 3.24 ms, and the corresponding fluorescence quantum efficiency is only 0.75%. Efficient multiphonon relaxation processes induced by the localized high-frequency vibrational modes in the bipyridyl group may lead to the extremely low quantum efficiency observed. The thermal line broadening and shifts of the 4G(5/2)(1) --> 6F(1/2) transition were observed and fitted very well by the McCumber-Sturge equations with an assumption of Raman phonon scattering processes as the leading relaxation mechanism. The Debye temperature for this crystal is predicted to be 350 K.

Converting Eu3+ between defect sites in BaFCl for persistent spectral hole burning

Persistent spectral hole burning (PSHB) is demonstrated in the (7)F(0)-->(5)D(0) optical transition of Eu(3+) doped into crystals of BaFCl. For Eu(3+) ions at two different lattice sites, persistent holes can be burned at temperatures below 77 K. The characteristics of the hole-burning process suggest that the observed PSHB effect is due to laser-excitation-induced site-to-site conversion. One type of Eu(3+) site is converted into another type of defect site. This process is not optically reversible, and holes can be erased only when the temperature increases to 150 K.