Production of mutants with high cold tolerance in spring canola (<Emphasis Type="Italic">Brassica napus</Emphasis>)

A major factor affecting spring canola (Brassica napus) production in Canada is killing frosts during seedling development in the spring and seed maturation in the fall. The objective of this study was to explore the possibility of producing spring canola lines with mutations that have altered biochemical pathways that increase cold tolerance. The approach was to generate UV point mutations in cultured microspores followed by chemical in vitro selection of individual mutant microspores or embryos resulting in measurable alterations to various biochemical pathways with elevated levels of key defense signaling molecules such as, salicylic acid (SA), p-Fluoro-d,l-Phenyl Alanine (FPA), and jasmonic acid (JA). In addition, since proline (Pro) is known to protect plant tissues in the cold-induced osmotic stress pathway, mutants that overproduce Pro were selected in vitro by using three Pro analogues: hydroxyproline (HP), azetidine-2-carboxylate (A2C); and, 3,4-dehydro-d,l-proline (DP). Of the 329 in vitro selected mutant embryos produced, 74 were identified with significant cold tolerance compared to their donor parents through indoor freezer tests at −6°C, and 19 had better winter field survival than winter canola checks. All chemically selected mutant doubled haploids with increased cold tolerance compared well with parent lines for all seed quality and agronomic parameters. Development of increased frost tolerant cultivars should allow for spring canola to be produced in western Canada without compromising seed quality.     

Pomological and Nutraceutical Properties in Apricot Fruit: Cultivation Systems and Cold Storage Fruit Management

We have investigated the effect of cultivation systems and fruit post-harvest management on the antioxidant properties of apricot fruits. Trees of five cultivars ‘Tyrinthos’, ‘Cafona’, ‘Bella d’Italia’, ‘Vitillo’ and ‘Pellecchiella’ were cultivated under integrated and organic systems. Fruits were collected at full maturity stage and analyzed either immediately or after storage at 4±0.5 °C and 85% of relative humidity for seven and 14 days. The main pomological traits (weight, colour, flesh firmness, total soluble sugars, titratable acidity) and antioxidant properties were analyzed. The total antioxidant capacity (TAC by TEAC method), total phenols content (TP by Folin-Ciocalteu method) and carotenoid content by HPLC-DAD were monitored. Cultivar characterization by principal component analysis (PCA) indicated a large variability on pomological and antioxidant properties of apricot fruits. ‘Bella d’Italia’ showed better TAC and TP values compared to the other cultivars. ANOVA interactions between cultivar and cultivation system (organic/integrated) were found for the antioxidant properties. These interactions may help to select a set of genotypes with better performances under organic system, which in our study might be indicated in ‘Cafona’ and ‘Bella d’Italia’.     

Deformation analysis of timber-framed panel dome structure I: simulation of a dome model connected by elastic springs

This study develops an analytical method that enables the simulation of the deformation of timber-framed plywood panel dome structures, of which strength is largely governed by the rigidity of joints. A hybrid truss structure model was employed to analyze this structure. In this model, we aimed to incorporate the mechanical properties of bolted and nailed joints, which were employed to build the structures, although the present investigation focused on the deformation characteristics of a dome in which the panel elements were connected mutually by elastic springs. The results of the theoretical analysis are compared with those obtained by experiments. The simulated results were found to be in good agreement with the results of the experiments under similar loading conditions.     

Estimation of the spawning grounds of chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> and spotted mackerel <Emphasis Type="Italic">Scomber australasicus</Emphasis> in the East China Sea based on catch statistics and biometric data

The spawning grounds of the chub mackerel (Scomber japonicus) and spotted mackerel (Scomber australasicus) in the East China Sea were estimated based on catch statistics of the Japanese large- and medium-type purse seine fishery from 1992 to 2006. Biometric data were obtained from specimens caught by purse seiners in the East China Sea from 1998 to 2006. Gonadosomatic index (GSI) at 50% sexual maturity of chub mackerel and spotted mackerel females was 2.5 and 2.6, respectively. Using this criterion for GSI, chub mackerel larger than 275 mm and spotted mackerel larger than 310 mm in fork length were considered to be mature. Mature chub mackerel was observed in the area of 15–22°C sea surface temperature (SST), and mature spotted mackerel was observed in the area of 17–25°C SST. The spawning period of chub mackerel ranged from February to June, and that of spotted mackerel ranged from February to May in the East China Sea. The spawning grounds were estimated from the distributions of catch per unit effort (CPUE) of spawners and SST. As a result, the spawning ground of chub mackerel was estimated to be in the central and southern part of the East China Sea and the area west of Kyushu in February, March, and April, and in the central part of the East China Sea, the area west of Kyushu and Tsushima Straight in May, and in Tsushima Straight and western part of the Sea of Japan in June. The spawning ground of spotted mackerel was estimated to be in the central and southern part of the East China Sea and southern coastal area of Kyushu in February, March, and April, and the central and southern part of the East China Sea and the area west of Kyushu in May.     

Breakdown and macroinvertebrate colonization of needle and leaf litter in conifer plantation streams in Shikoku,southwestern Japan

Breakdown and macroinvertebrate colonization of conifer needles (Cryptomeria japonica) and deciduous broadleaves (Euptelea polyandra) were investigated using litter bags in two study sites in streams flowing through a conifer plantation of C. japonica in Shikoku, southwestern Japan (one site with conifer canopy and another with mixed conifer and broadleaved canopy). Breakdown rates and macroinvertebrate densities were compared between litter species (conifer needle vs broadleaf) and between the two sites (conifer vs mixed canopy) to determine (1) whether breakdown rate of broadleaves is higher than conifer needles, (2) whether macroinvertebrates prefer broadleaves to conifer needles, and (3) whether the difference in riparian canopy is reflected in macroinvertebrate abundance. The results indicated that breakdown rates of broadleaves were higher than those of conifer needles, suggesting poorer quality of the latter as food for macroinvertebrates. Differences in macroinvertebrate density between needles and broadleaves were generally consistent with those in breakdown rates: broadleaves tended to have higher densities than needles, suggesting that conifer needles were not preferred by macroinvertebrates. However, total macroinvertebrate density in the conifer site was not significantly different from that in the mixed site, although the dominant shredder taxon differed (conifer site: gammarids; mixed site: lepidostomatids). Although conifer needles are low-quality food for macroinvertebrates, this may offer some advantages. Conifer needles remain on the streambed for longer periods owing to their lower breakdown rates, being a constantly available resource. In addition, accumulations of conifer litter may effectively trap and retain particulate organic matter.     

Lack of biocontrol capacity in a non-pathogenic mutant of <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f. sp. <Emphasis Type="Italic">melonis</Emphasis>

The aim of this study was to assess the biocontrol capacity of rev157, a non-pathogenic mutant of a pathogenic strain of Fusarium oxysporum f. sp. melonis (Fom24). Inoculated in association with the virulent parental strain, the mutant rev157 did not protect the host plant (muskmelon) against infection by Fom24. Applied on flax, a non-host plant, the mutant rev157 was not able to protect it against its specific pathogen F. oxysporum f. sp. lini. On the contrary the parental strain Fom24 did protect flax as well as a soil-borne biocontrol strain (Fo47). Since the mutant rev157 was affected neither in its growth in vitro nor in its capacity to penetrate into the roots, it can be speculated that the mutation has affected traits responsible for interactions within the plant. In F. oxysporum the pair of strains Fom24/rev157 is a good candidate to identify genes involved in the biocontrol capacity of F. oxysporum and to test the hypothesis of a link between capacity to induce the disease and capacity to induce resistance in the plant.     

Influence of NaCl salinity on some physiological aspect of strawberry cv. Camarosa

One of the most important elements affecting the growth and development of a plant is salinity. Therefore, to evaluate the effect of salinity on some physiological aspect of Strawberry (Fragaria x ananassa Duch.) plants cv. Camarosa, a greenhouse experiment was conducted at Vali-e-Asr University of Rafsanjan in 2009. This study was carried out as Factorial experiment based on RCD design with 4 replications to determine the influence of salinities (0, 30, 60 and 9 mMol.L-1) on proline, soluble sugars content, chlorophyll a (CHLa), chlorophyll b (CHLb), total chlorophyll (TC), Spad and chlorophyll florescence. Results indicated that fresh leaves tissue were used to measure proline, soluble protein and soluble sugars content, CHLa, CHLb, TC. Salinity treatment significantly increased proline content, soluble sugars while chlorophyll a (CHLa), chlorophyll b (CHLb), Spad and chlorophyll florescence significantly decreased. Nine day after NaCl exposure, Fv/Fm and Spad in 60 and 90 mM NaCl were significantly lower than control. It was concluded that this cultivar of strawberry may uses osmoregulation by increasing proline and soluble sugars level in order to tolerate salinity conditions.     

Shifts in disease resistance induced by growth regulators

Experiments on the effect of various compounds with plant growth regulating activity led to the hypothesis that conditions inhibitory to indoleacetic acid (IAA) action or leading to a decrease in the IAA level in cucumber seedlings would be unfavourable for the development of cucumber scab, caused byCladosporium cucumerinum. Susceptibility decreased as the result of treatment with growth retardants, which cause an increase in IAA-oxidase activity in the plants, whereas application of indoleacetic acid or compounds expected to decrease the rate of oxidative breakdown of IAA in the seedlings resulted in an increase of susceptibility. Growing the plants under various periods of illumination also influenced both the susceptibility of the plants and the IAA-oxidase activity in the hypocotyl tissue.To obtain further information about the relation between the increase in resistance and the increase in the rate of IAA oxidation, the effect of one compound, viz. L-threo-β-phenylserine (abbr. phenylserine) was studied in more detail. The rate of oxidative breakdown of IAA was increased in extracts of hypocotyls and cotyledons of plants treated with phenylserine as compared with extracts of tissue of untreated plants. Extracts of phenylserine-treated plants were found to contain a higher cofactor and/or a lower inhibitor content than those of control plants. The substances involved were not identified, but this result may indicate a shift in the concentrations of various phenols in the tissue.The question must remain open whether a shift in the concentration of phenols some-how effected by phenylserine treatment determines both degree of susceptibility and rate of IAA oxidation independently, or whether the rate of IAA breakdown and the resulting change in IAA content in the plants is directly related to the degree of susceptibility.     

New potyvirus isolated from <Emphasis Type="Italic">Cryptotaenia japonica</Emphasis>

 A potyvirus, for which the name Japanese hornwort mosaic virus (JHMV) is proposed, was isolated from Japanese hornwort plants (Cryptotaenia japonica) with mosaic disease symptoms. The virus was used to inoculate mechanically 34 plants belonging to 33 species of 10 families. Of these species seven from two families were infected. Faint chlorotic spots appeared on the inoculated leaves of Chenopodium quinoa and C. amaranticolor, but no systemic infection occurred in these plants. JHMV systemically infected only Umbelliferae plants; they did not infect 26 other species in eight families. JHMV was transmitted in a nonpersistent manner by aphids (Myzus persicae). The virus was a flexuous rod-shaped particle about 750 nm in length. Sequencing the nucleotides in the 3′ terminal region of JHMV revealed that the coat protein contains 280 amino acids with a molecular mass of 32.2 kDa. The nucleotide sequence of the coat protein of JHMV had the highest similarity with that of Zantedeschia mosaic virus (83.3%) compared to those of other potyviruses (57.0%–64.9%). An antiserum against JHMV reacted strongly with JHMV and weakly with Potato virus Y. These results indicate that JHMV is a new potyvirus. Received: September 9, 2002 / Accepted: November 7, 2002 RID="*" ID="*" The nucleotide sequence determined in this work appears in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession number AB081518