番茄纸的增稠工艺研究

通过对番茄纸成品进行感官鉴定，研究了不同增筒工艺对番茄纸质量的影响。结果表明：在每100g番茄浆料中添加0.2g海藻酸钠、0.1g明胶和1.0g淀粉进行复合协同增稠，最有利于提高产品质量。     

Production and genetic evaluation of interspecific hybrids within the genus Sambucus

Attempts were made to produce hybrids among various Sambucus species in order to change the plant structure of S. nigra, a medicinal plant of increasing agricultural importance. The first successful genetic recombination, involving four species, was conducted after the introduction of S. javanica from a South Pacific island. A series of genetic analyses of the involved species and some relatives was performed in order to obtain reliable data on genetic similarity among parental species and to confirm the hybrid nature of putative hybrids. The nuclear 2C DNA content revealed by flow cytometry of nine species showed limited variation, the greatest being in S. nigra (28.6 pg) and the smallest in S. caerulea (23.9 pg). Maximum parsimony analysis of seven Sambucus species was used to form two dendrograms, one based on the sequenced nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region and the other based on the cpDNA trnT‐trnF region. The results showed similar clustering into distinct groups; on both dendrograms S. nigra and S. javanica ES were closely related. Analysis of hybrid origin was based on the sequenced cpDNA region, genome size differences and PCR–RFLP analysis of the nrDNA ITS region. The seed parent and maternal origin of cpDNA was confirmed for all hybrids, while the pollen parent was confirmed in 21 of 22 putative hybrid plants tested.     

不同生长调节物质对丹参愈伤组织的诱导效应

以丹参(SalviamiltiorrhizaBunge)无菌苗的茎、叶为外植体,接种于附加2,4-D、NAA、6-BA及其组合的MS固体培养基上。结果表明:单独使用三种植物生长调节物质在一定浓度范围内均能产生愈伤组织;配合使用外源生长素和细胞分裂素,能获得出愈率高、生长快、质量好的愈伤组织;最佳组合的诱导培养基为MS 2,4-D2．0mg／L 6-BA1．0mg／L;2,4-D对丹参愈伤组织的诱导有促进作用;但当2,4-D的浓度在4mg／L以上时,对愈伤组织的生长有抑制作用。     

葡萄糖氧化酶基因在棉花中的高效转化——转基因再生棉株的获得

利用农杆菌介导法把葡萄糖氧化酶基因转移到棉花中 ,获得了再生植株 ,并对影响棉花愈伤组织分化和植株再生的因素作了探讨。离体分子检测表明 ,外源基因已整合到棉花基因组中     

Molecular characerization of the interaction between the fungal pathogen Cladosporium fulvum and tomato

The fungus Cladosprium fulvum is a biotrophic leaf pathogen of tomato. The fungus develops in the intercellular space without forming specialized feeding structures and does not affect the leaf tissue. The outcome of the C. fulvum-tomato interaction can be described by the gene-for-gene model. Failure of infection is expressed by a hypersensitive response. Two fungal proteins, ECP1 and ECP2, have been isolated and their corresponding genes have been cloned. In a compatible interaction including many physiological races ECP1 and ECP2 are highly produced and a role in pathogenicity is suggestive. The ecp1 gene shows some homology with tumor necrosis factor receptors (TNFRs) while the ecp2 gene shows no homology with sequences known in data bases. However, disruption of one of the two genes showed no reduced pathogenicity of the fungus. Two race-specific elicitors, AVR4 and AVR9, have been isolated and their corresponding genes have been cloned. The avirulence genes Avr4 and Avr9 are only present in C. fulvum avirulent on Cf-4 and Cf-9 cultivars, respectively. The expression of these two genes is, like the expression of the ecp genes, highly induced when the fungus grows in planta. Disruption of the Avr9 gene in wild type avirulent races leads to virulence on tomato genotypes carrying the complementary resistance gene Cf-9. A single base-pair change in the avirulence gene Avr4 leads to virulence on tomato genotypes carrying the Cf-4 resistance gene. Isolation, characterization and possible function of ECP1, ECP2, AVR4, and AVR9 will be discussed.     

Antimicrobial screening of Mentha piperita essential oils

Essential oils of peppermint Mentha piperita L. (Lamiaceae), which are used in flavors, fragrances, and pharmaceuticals, were investigated for their antimicrobial properties against 21 human and plant pathogenic microorganisms. The bioactivity of the oils menthol and menthone was compared using the combination of in vitro techniques such as microdilution, agar diffusion, and bioautography. It was shown that all of the peppermint oils screened strongly inhibited plant pathogenic microorganisms, whereas human pathogens were only moderately inhibited. Chemical compositions of the oils were analyzed by GC and GC/MS. Using the bioautography assay, menthol was found to be responsible for the antimicrobial activity of these oils.     

Edible arabinoxylan-based films. 1. Effects of lipid type on water vapor permeability,film structure,and other physical characteristics

Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was observed in OK35-AX emulsion films. Contact angles of water comparable to those observed for LDPE films (>90 degrees ) are measured on the OK35-AX film surface. Finally, only triolein-AX emulsion films had elongation higher than films without lipid. These results suggest that OK35 enhances functional properties of AX-based films and should be retained for further research.