Sources of crown rot (Phytophthora cactorum) infection in strawberry and the effect of cold storage on susceptibility to the disease

Cold-stored plants of strawberry cultivars Tamella, Cambridge Favourite and Redgauntlet were more susceptible to pathogenic isolates of Phytophthora cactorum than similar plants which had not been cold-stored. Indigenous nonpathogenic isolates of P. cactorum did not cause crown rot in cold-stored plants, although a small number of symptomless latent infections occurred. The majority of P. cactorum isolates causing crown rot symptoms were taken from infected strawberry crowns, although two isolates from gooseberry plants, but of uncertain origin, were also pathogenic. Outbreaks of crown rot in areas with no previous history of the disease therefore probably result from the importation of non-indigenous inoculum with planting material. Assessments of the timing of infection in relation to cold storage revealed that a high incidence of death in the cold store and chronic wilt symptoms on planting from the store resulted from initiating symptomless infections prior to cold storage. However, infection during the period immediately after cold storage resulted in rapid wilt symptoms of Phytophthora crown rot. When plated in sterile distilled water for 24 h, pieces of tissue from infected plants which had died during cold storage produced large numbers of sporangia and zoospores. This indicates that such plant material could provide a potent source of inoculum for infections in the post storage thawing environment. It is proposed that a combination of heightened host susceptibility resulting from cold storage and the presence of scatted latent infections or infected debris among the plants could result in a sudden, large scale appearance of crown rot, as sometimes is seen with cold-stored plantings of strawberries.     

The use of hydrogen peroxide to control postharvest decay on 'Galia' melons

Sanosil-25, a disinfectant containing 48% hydrogen peroxide and silver salts as stabilising agents, inhibited the mycelial growth of the two main decays causing fungi of melons, Alternaria alternata and Fusarium solani in vitro at concentrations between 5000 and 10 000 μl litre^-1. However, in in vivo experiments, Sanosil-25 markedly decreased decay at a concentration of 5000 μl litre^-1 when incorporated into a wax treatment and produced no phytotoxic effect. This treatment may provide an alternative to imazalil which, although more effective, gives problems with residue levels. A concentration of 10 000 μl litre^-1 proved phytotoxic.     

Growth of Ectopic Dendrites on Cortical Pyramidal Neurons in Neuronal Storage Diseases Correlates with Abnormal Accumulation of GM2 Ganglioside

Abstract: Ganglioside analysis and quantitative Golgi studies of the cerebral cortex of cats with ganglioside and nonganglioside lysosomal storage diseases reveal a correlation between the amount of accumulated GM2 ganglioside and the extent of ectopic dendrite growth on cortical pyramidal neurons. This correlation was not observed with any of the other gangliosides assayed for, including GM1 ganglioside. These results suggest a specific role for GM2 ganglioside in the initiation of ectopic neurites on pyramidal cells in vivo and are consistent with the developing hypothesis that different gangliosides have specific roles in different cell types dependent upon the receptor or other effector molecules with which they may interact.     

Linkage disequilibrium in crosses between Illinois maize strains divergently selected for protein percentage

The objectives of this study were two fold: (1) to determine whether divergent selection for kernel protein concentration, which produced the Illinois high protein (IHP), Illinois low protein (ILP), reverse low protein (RLP), and reverse high protein (RHP) maize (Zea mays L.) strains, had generated coupling-phase linkages among genes controlling protein concentration or other traits and (2) to measure the effectiveness of random mating in reducing linkage disequilibrium in segregating generations from crosses between the strains. To achieve these objectives, design III progenies from the F₂ and F₆ (produced by random mating the F₂) from the crosses of IHP × ILP, IHP × RHP, ILP × RLP, and RHP × RLP were evaluated. Estimates of additive variance for percent protein in the crosses of IHP × ILP and ILP × RLP were significantly less in the F₆ than in the F₂ indicating the presence of coupling-phase linkages in the parents and their breakup by random mating. In addition, a significant reduction in dominance variance for grain yield from the F₂ to the F₆ in IHP × ILP suggested the presence of repulsion-phase linkages. No other evidence of coupling or repulsion-phase linkages was found for any of the traits measured. These results demonstrate the effectiveness of long-term divergent selection in the development of coupling-phase linkages and of random mating to dissipate linkage disequilibrium.Research supported by the Illinois Agricultural Experiment Station     

The legumin gene family: a reconstructed Vicia faba legumin gene encoding a high-molecular-weight subunit is related to type B genes

Nucleotide sequence information from a partial genomic clone, a cDNA clone, a RACE clone and a PCR fragment was combined to reconstruct the first reported complete gene sequence encoding a large legumin subunit, designated LelB3. The length difference to the well-characterized major legumin subunits is caused by an extended glutamin/glutamic acid-rich region encoded by the C-terminal part of the chain. Amino acid sequence comparisons reveal that gene LelB3 is more closely related to B-type than to A-type legumin genes of Vicia faba. Gene LelB3 is a member of a small gene family as indicated by published (Pich and Schubert, Biol Zbl 112 (1993); 342–350) and limited own data.     

Effects of an antisense napin gene on seed storage compounds in transgenic Brassica napus seeds

To manipulate the quantity and quality of storage components in Brassica napus seeds, we have constructed an antisense gene for the storage protein napin. The antisense gene was driven by the 5-flanking region of the B. napus napin gene to express antisense RNA in a seed-specific manner. Seeds of transgenic plants with antisense genes often contained reduced amounts of napin. In some transgenic plants, no accumulation of napin was observed. However, the total protein content of transgenic and wild-type seeds did not differ significantly. Seeds lacking napin accumulated 1.4 to 1.5 times more cruciferin than untransformed seeds, although the oleosin content was not affected. Fatty acid content and composition in the seeds of transgenic plants were also analyzed by gas chromatography. Though the total fatty acid content of the transformants was the same as that of non-transformants, there was a reduction in 18:1 contents and a concomitant increase of 18:2 in seeds with reduced napin levels. This observed change in fatty acid composition was inherited in the next generation.     

The glycinin box: a soybean embryo factor binding motif within the quantitative regulatory region of the 11S seed storage globulin promoter

The soybean embryo factor binding sequence in the glycinin A₂B_1a gene promoter was delimited to an A/T-rich 9 bp sequence, 5-TAATAATTT-3, designated as the glycinin box, by DNA footprinting and gel mobility shift assay using synthetic oligonucleotides. It was shown that the interaction with the factor takes place at a defined DNA sequence rather than at random A/T-rich sequence blocks in the glycinin 5 flanking region. There are four glycinin boxes in the quantitative regulatory region between positions – 545 and – 378 of the glycinin A₂B_1a promoter. Multiple nonamer motifs similar to the glycinin box were also found in the equivalent regions of other glycinin and legumin promoters, suggesting that they must be conserved as a binding site for the embryo factor that activates the differential and stage-specific expression of seed 11S globulin genes in leguminous plants.     

Survival of Aeromonas hydrophila and Listeria monocytogenes on fresh vegetables stored under moderate vacuum

Storage at 6.5°C under moderate vacuum effectively prevented growth of Aeromonas hydrophila on chicory endive, but had only a limited inhibitory effect on the growth of the organism on mung bean sprouts. Growth of Listeria monocytogenes on chicory endive was strongly stimulated under these conditions, whereas it was decreased on mung-bean sprouts.     

Comparison of two methods of storing breast fine needle aspirates (FNAs) using oestrogen receptor immunocytochemical assay as a method of evaluating the storage methods

Two methods of storing fine needle aspirates were compared in 14 patients with breast cancer. the methods of storage were: (1) as a Cytospin slide prepared immediately from the aspirated material and stored at −80°C; (2) as a suspension of cells in tissue culture medium, stored at −80°C. the effect of storage on the cells was assessed by means of an oestrogen receptor immunocytochemical assay (ER-ICA). an ER positivity of 100% was obtained by ER-ICA staining of cells after storage method 1, whilst all of the specimens stored by method 2 were ER-negative. the data demonstrate that cells stored in tissue culture medium at −80°C are not suitable for ER measurement. the storage method of choice for specimens intended for ERICA is as a Cytospin slide. the ER status of cells deposited on Cytospin slides prepared immediately and stored at −80°C for 2 years could be demonstrated despite the delay in processing the specimen.     

Molecular heterogeneity of Cowpea (Vigna unguiculata Fabaceae) seed storage proteins

81 wild forms and 110 cultivated cowpea,Vigna unguiculata, accessions from 21 countries of Africa were screened for variability in seed storage proteins. Total seed proteins, albumin and globulin fractions were investigated by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) of nonreduced and/or reduced samples in one- and two-dimensional procedures. The globulin fraction is heterogeneous in molecular weight and contains both legumin-like components and three to six nondisulfide-linked subunits. Three globulin subunits, with molecular weights 110, 76, and 41 kD were found to be composed of disulfide-linked polypeptides. In the nondisulfide-linked fraction, both cultivated and wild forms exhibited patterns of four types (A–D). This fraction contains polypeptide subunits of molecular weights 62, 56, and 52 kD for A type, 62, 56, 54, and 52 kD for B type, 62, 56, 52, and 50 kD for C type, and at least 62, 56, 54, 52, 50, and 49 kD for D type. These subunits present similar multiple charge forms but C and D types possess more basic specific 50 and 49 kD nondisulfide linked components. Major albumin fraction contains subunits of 94, 86, 32, and 24kD. No infraspecific variation was observed in albumin or legumin-like fractions. The discussion is focussed on the relations between genetic variability assessed by storage protein coding genes and phenotypic variability.