Caulogenic callus induction and adventitious bud formation from embryos of long-term stored seeds ofPicea jezoensis

Caulogenic calli with a high differentiation potency were induced from mature embryos ofPicea jezoensis seeds stored over a long time, for 29 years, resulting in the active formation of adventitious buds. Embryos began to induce calli within 3 weeks of cultivating on LP medium containing 3 μM BAP and 1 μM 2,4-D. Then, the calli proliferated and transformed into caulogenic calli with bud primordia in 8 weeks. The caulogenic calli increased actively with the addition of 500 mg/l ofl-glutamine in the medium. Furthermore, caulogenic calli, induced on LP medium containingl-glutamine, resulted in the formation of adventitious buds, which elongated after transferring the calli into LP medium with 0.1 μM BAP, but withoutl-glutamine. It appears that the number of adventitious buds and the process of shoot elongation are influenced by the kind of nitrogen contained in the medium for callus induction. A part of this study was presented at the 107th Annual Meeting of the Japanese Forestry Society (1996).     

Influence of osmotic pressure on somatic embryo maturation in Pinus densiflora

The effect of an osmoticum, polyethylene glycol (PEG), on somatic embryo production was examined using embryogenic cells of Pinus densiflora. In the basal medium containing 30 μM abscisic acid and 6% maltose, the quality of the embryos formed was poor even though somatic embryos were produced. The addition of PEG with molecular weight of 4000 or 8000 significantly enhanced the development of both the quality and quantity of somatic embryos. Furthermore, higher levels of a constant osmotic pressure with PEG 8000 in a range from about 300 to 450 mmol/kg could remarkably enhance the morphogenesis of somatic embryos and their number of embryos produced. A higher stable osmotic pressure with an appropriate molecular weight of PEG is a key factor for the production of good quality somatic embryos in P. densiflora.     

Effect of heat on cambial reactivation during winter dormancy in evergreen and deciduous conifers

Responses of cambium to warming were recorded three times (December 14-27, 1990, January 18-February 3 and February 27-March 13, 1991) on 14-year-old Cryptomeria japonica D. Don and four times (December 12-26, 1990, January 18-February 2, February 26-March 12 and March 28-April 13, 1991) on 27-year-old Larix leptolepis Gord., during a period of winter cambial dormancy. Stem surfaces at breast height, mid-tree height and the crown base were warmed to 25-30 degrees C for 2 weeks. After heat treatment, cambia in the treated regions and in untreated regions 1 m above each treated area were examined by optical and transmission electron microscopy (TEM). In C. japonica, heat treatment often resulted in cambial reactivation in the treated regions, and this response to heat gradually increased as the dormant season passed from winter to spring. Conversely, in L. leptolepis, no cell division was observed in the cambial region of warmed stems until natural resumption of cambial activity, which occurred after bud break.     

Mapping of a gene that confers short lateral branching (slb) in melon (Cucumis melo L.)

Plant architecture plays an important role in the yield, product quality, and cultivation practices of many crops. Branching pattern is one of the most important components in the plant architecture of melon (Cucumis melo L.). ‘Melon Chukanbohon Nou 4 Go’ (Nou-4) has a short-lateral-branching trait derived from a weedy melon, LB-1. This trait is reported to be controlled by a single recessive or incompletely dominant major gene called short lateral branching (slb). To find molecular markers for marker-assisted selection of this gene, we first constructed a linkage map using 94 F₂ plants derived from a cross between Nou-4 and ‘Earl’s Favourite (Harukei-3)’, a cultivar with normal branching. We then conducted quantitative trait locus (QTL) analysis and identified two loci for short lateral branching. A major QTL in linkage group (LG) XI, at which the Nou-4 allele is associated with short lateral branching, explained 50.9 % of the phenotypic variance, with a LOD score of 12.5. We suggest that this QTL corresponds to slb because of the magnitude of its effect. Another minor QTL in LG III, at which the Harukei-3 allele is associated with short lateral branching, explained 9.9 % of the phenotypic variance, with a LOD score of 4.2. Using an independent population, we demonstrated that an SSR marker linked to the QTL in LG XI (slb) could be used to select for short lateral branching. This is the first report of mapping a gene regulating the plant architecture of melon.     

An SSR-based genetic map of pepper (Capsicum annuum L.) serves as an anchor for the alignment of major pepper maps

Of the Capsicum peppers (Capsicum spp.), cultivated C. annuum is the most commercially important, but has lacked an intraspecific linkage map based on sequence-specific PCR markers in accord with haploid chromosome numbers. We constructed a linkage map of pepper using a doubled haploid (DH) population derived from a cross between two C. annuum genotypes, a bell-type cultivar ‘California Wonder’ and a Malaysian small-fruited cultivar ‘LS2341 ({"type":"entrez-nucleotide","attrs":{"text":"JP187992","term_id":"347495878"}}JP187992)’, which is used as a source of resistance to bacterial wilt (Ralstonia solanacearum). A set of 253 markers (151 SSRs, 90 AFLPs, 10 CAPSs and 2 sequence-tagged sites) was on the map which we constructed, spanning 1,336 cM. This is the first SSR-based map to consist of 12 linkage groups, corresponding to the haploid chromosome number in an intraspecific cross of C. annuum. As this map has a lot of PCR-based anchor markers, it is easy to compare it to other pepper genetic maps. Therefore, this map and the newly developed markers will be useful for cultivated C. annuum breeding.     

Identification of genes expressed during spore germination of Mycosphaerella pinodes

Mycosphaerella blight, caused by Mycosphaerella pinodes, is one of the major diseases of cultivated pea (Pisum sativum L.). To isolate the genes that are up- and down-regulated during spore germination, suppression subtraction hybridization (SSH) was performed between ungerminated and germinated spores. The 232 and 128 clones from forward and reverse libraries, respectively, were collected, sequenced, and analyzed with a BLASTX homology search. About 95% of the 32 selected clones were expressed during spore germination on a paper sheet and during infection of pea leaves. We discuss the applicability of the SSH libraries for analyzing M. pinodes genes involved in the early stage of infection.     

Retrospective serological analysis of spontaneous CDV infection in 192 dogs

Spontaneous cases of canine distemper virus (CDV) infection were serologically evaluated. The 192 dogs in which CDV antigen was confirmed from tonsil by immunohistological examination were 2- to 4-months old, of various breeds, and unvaccinated. The prognoses were good in 74 dogs with significantly high levels of anti-CDV passive hemolytic aggregation (PHA) titer. In the other 118 dogs with poor prognoses, anti-CDV PHA titer was not detected. Anti-CDV PHA titer had the most significant association with the prognoses of CDV infection, and could be the most reliable and useful indicator for evaluating such prognoses.     

Role of sorbitol in manufacturing dried seafood from heated squid meat

SUMMARY: Japanese common squid meat was heat-treated at 80°C for 1 min, cured with 1.0 M sorbitol solution (pH 7.0) at 4°C for 18 h, and dried further at 30°C (60% relative humidity) for 16 h. Osmotic dehydration during the sorbitol curing process and slow moisture vaporization at the initial drying period were observed regardless of the heat denaturation of muscle protein. Simultaneously, lowering the amount of moisture vaporized in the falling rate of the drying period caused a shortening of the total drying time. Furthermore, the shear force of the dried product from heat-treated meat was kept at a lower value by sorbitol curing, although the suppression effect of sorbitol on the hardening of dried meat was lost by protein denaturation. These results are useful for understanding the role of sorbitol in reducing drying time and in eliminating excess hardening of dried squid products.